Merge branch 'development' into deduce_if_builtins_are_present

# Conflicts:
#	include/etl/generators/type_traits_generator.h
#	include/etl/profiles/arduino_arm.h
#	include/etl/profiles/armv5.h
#	include/etl/profiles/armv5_no_stl.h
#	include/etl/profiles/armv6.h
#	include/etl/profiles/armv6_no_stl.h
#	include/etl/profiles/armv7.h
#	include/etl/profiles/armv7_no_stl.h
#	include/etl/profiles/cpp03.h
#	include/etl/profiles/cpp03_no_stl.h
#	include/etl/profiles/cpp11.h
#	include/etl/profiles/cpp11_no_stl.h
#	include/etl/profiles/cpp14.h
#	include/etl/profiles/cpp14_no_stl.h
#	include/etl/profiles/cpp17.h
#	include/etl/profiles/cpp17_no_stl.h
#	include/etl/profiles/determine_builtin_support.h
#	include/etl/profiles/ticc.h
#	include/etl/profiles/ticc_no_stl.h
#	include/etl/type_traits.h

.bazelrc

@@ -0,0 +1,26 @@
+# Bazel settings for ETL
+build --enable_bzlmod
+build --cxxopt=-std=c++17
+
+# Cross-compilation: build flags + QEMU (mirrors .devcontainer/run-tests.sh)
+# Each config sets CC + tool env vars so Bazel's auto-configured toolchain
+# finds the full cross-tool suite, and --run_under for QEMU execution.
+build:armhf    --repo_env=CC=arm-linux-gnueabihf-gcc --repo_env=AR=arm-linux-gnueabihf-ar --repo_env=LD=arm-linux-gnueabihf-ld --repo_env=NM=arm-linux-gnueabihf-nm --repo_env=STRIP=arm-linux-gnueabihf-strip --repo_env=OBJDUMP=arm-linux-gnueabihf-objdump
+build:armhf    --cxxopt=-std=c++23 --copt=-DETL_NO_STL --copt=-O0
+test:armhf     --run_under=/usr/bin/qemu-arm-static
+
+build:i386     --repo_env=CC=i686-linux-gnu-gcc --repo_env=AR=i686-linux-gnu-ar --repo_env=LD=i686-linux-gnu-ld --repo_env=NM=i686-linux-gnu-nm --repo_env=STRIP=i686-linux-gnu-strip --repo_env=OBJDUMP=i686-linux-gnu-objdump
+build:i386     --cxxopt=-std=c++23 --copt=-DETL_NO_STL --copt=-O0
+test:i386      --run_under=/usr/bin/qemu-i386-static
+
+build:powerpc  --repo_env=CC=powerpc-linux-gnu-gcc --repo_env=AR=powerpc-linux-gnu-ar --repo_env=LD=powerpc-linux-gnu-ld --repo_env=NM=powerpc-linux-gnu-nm --repo_env=STRIP=powerpc-linux-gnu-strip --repo_env=OBJDUMP=powerpc-linux-gnu-objdump
+build:powerpc  --cxxopt=-std=c++23 --copt=-DETL_NO_STL --copt=-O0
+test:powerpc   --run_under=/usr/bin/qemu-ppc
+
+build:riscv64  --repo_env=CC=riscv64-linux-gnu-gcc --repo_env=AR=riscv64-linux-gnu-ar --repo_env=LD=riscv64-linux-gnu-ld --repo_env=NM=riscv64-linux-gnu-nm --repo_env=STRIP=riscv64-linux-gnu-strip --repo_env=OBJDUMP=riscv64-linux-gnu-objdump
+build:riscv64  --cxxopt=-std=c++23 --copt=-DETL_NO_STL --copt=-O0
+test:riscv64   --run_under=/usr/bin/qemu-riscv64-static
+
+build:s390x    --repo_env=CC=s390x-linux-gnu-gcc --repo_env=AR=s390x-linux-gnu-ar --repo_env=LD=s390x-linux-gnu-ld --repo_env=NM=s390x-linux-gnu-nm --repo_env=STRIP=s390x-linux-gnu-strip --repo_env=OBJDUMP=s390x-linux-gnu-objdump
+build:s390x    --cxxopt=-std=c++23 --copt=-DETL_NO_STL --copt=-O0
+test:s390x     --run_under=/usr/bin/qemu-s390x-static

.bazelversion

@@ -0,0 +1 @@
+8.5.1

.clang-format

@@ -1,57 +1,184 @@
 ---
-#------------------------------------
-# Configuration for clang-format v12
-#------------------------------------
+BasedOnStyle: LLVM
+Standard:     Auto # let the formatter accept any C++ standard
 
-Language: Cpp
+# =============================================================================
+# Indentation
+# =============================================================================
+TabWidth:                          2
+ContinuationIndentWidth:           2
+ConstructorInitializerIndentWidth: 2
+NamespaceIndentation:              All        # everything inside namespace is indented
+IndentCaseLabels:                  true       # case labels at switch-body indent level
+IndentCaseBlocks:                  true       # indent block inside case label
+IndentExternBlock:                 Indent
+IndentWrappedFunctionNames:        true       # keep function name at same indent as return type
+IndentPPDirectives:                BeforeHash # nested #if / #include get indented before the #
+PPIndentWidth:                     2
 
-BasedOnStyle: Chromium
+# =============================================================================
+# Braces & line-break style
+# =============================================================================
+BreakBeforeBraces:               Allman
+BreakConstructorInitializers:    BeforeComma   # colon on new line, commas lead
+BreakInheritanceList:            BeforeComma
+BreakBeforeBinaryOperators:      NonAssignment
+BreakStringLiterals:             false
+AlwaysBreakTemplateDeclarations: Yes           # template <…> always on its own line
+BreakAfterAttributes:            Always
 
-SortIncludes: true
-IncludeBlocks: Preserve
+# =============================================================================
+# Short statements
+# =============================================================================
+AllowShortBlocksOnASingleLine:     Empty
+AllowShortFunctionsOnASingleLine:  Empty  # only empty bodies: void f() {}
+AllowShortCaseLabelsOnASingleLine: true   # case X: stmt; break; on one line
+AllowShortLoopsOnASingleLine:      true
+AllowShortLambdasOnASingleLine:    Inline
+
+# =============================================================================
+# Empty lines
+# =============================================================================
+KeepEmptyLinesAtTheStartOfBlocks: false
+EmptyLineBeforeAccessModifier:    Always # blank line before public:/private:/protected:
+EmptyLineAfterAccessModifier:     Always # blank line after  public:/private:/protected:
+InsertNewlineAtEOF:               true
+
+# =============================================================================
+# Spacing
+# =============================================================================
+SpacesInAngles:            Leave # preserve C++03 "> >" vs C++11 ">>"
+SpacesInContainerLiterals: false
+
+# =============================================================================
+# Alignment
+# =============================================================================
+PointerAlignment:             Left # T* ptr, const T& ref
+ReferenceAlignment:           Left
+AlignConsecutiveAssignments:  true
+AlignConsecutiveDeclarations: true
+AlignConsecutiveBitFields:    true
+AlignConsecutiveMacros:       true # align macro bodies
+
+# =============================================================================
+# Line length and wrapping
+# =============================================================================
+ColumnLimit:    150
+ReflowComments: true # preserve hand-formatted comment rulers
+AlignEscapedNewlines: Left
+
+# =============================================================================
+# Includes
+# =============================================================================
 IncludeCategories:
   - Regex:    '^(<|")(.*/)?platform\.h(>|")$'
+    Priority: -1
+  - Regex:    'private'
     Priority: 1
   - Regex:    '.*'
-    Priority: 2
+    Priority: 0
 
-BinPackParameters: false
-BitFieldColonSpacing: Both
+# =============================================================================
+# Arguments, parameters and constructor initialisers
+# =============================================================================
+PackConstructorInitializers: Never # each initialiser on its own line
 
-BreakBeforeBraces: Allman
-BreakConstructorInitializers: BeforeComma
+# =============================================================================
+# Namespaces and using declarations
+# =============================================================================
+SortUsingDeclarations: Lexicographic
 
-AllowShortBlocksOnASingleLine: false
-AllowShortCaseLabelsOnASingleLine: true
-AllowShortFunctionsOnASingleLine: None
-AllowShortIfStatementsOnASingleLine: false
+# =============================================================================
+# Macro-aware formatting
+# =============================================================================
+# ETL-specific macros that should be treated as statement-level constructs
+StatementMacros:
+  - ETL_DECLARE_DEBUG_COUNT
+  - ETL_INCREMENT_DEBUG_COUNT
+  - ETL_DECREMENT_DEBUG_COUNT
+  - ETL_ADD_DEBUG_COUNT
+  - ETL_STATIC_ASSERT
+  - ETL_ASSERT
+  - ETL_ASSERT_OR_RETURN
+  - ETL_ASSERT_OR_RETURN_VALUE
+  - ETL_ASSERT_FAIL
+  - ETL_ASSERT_FAIL_AND_RETURN
+  - ETL_ASSERT_FAIL_AND_RETURN_VALUE
+  - ETL_MOVE
+  - ETL_ENUM_CLASS
+  - ETL_ENUM_CLASS_TYPE
+  - ETL_IF_CONSTEXPR
 
-AllowAllArgumentsOnNextLine: true
-AllowAllParametersOfDeclarationOnNextLine: true
+# Macros that behave like attributes or specifiers.
+AttributeMacros:
+  - ETL_NORETURN
+  - ETL_FINAL
+  - ETL_OVERRIDE
+  - ETL_EXPLICIT
+  - ETL_DELETE
+  - ETL_CONSTANT
+  - ETL_CONSTEXPR
+  - ETL_CONSTEXPR11
+  - ETL_CONSTEXPR14
+  - ETL_CONSTEXPR17
+  - ETL_CONSTEXPR20
+  - ETL_CONSTEXPR23
+  - ETL_CONSTEVAL
+  - ETL_NODISCARD
+  - ETL_NORETURN
+  - ETL_DEPRECATED
+  - ETL_DEPRECATED_REASON
+  - ETL_LIKELY
+  - ETL_UNLIKELY
+  - ETL_FALLTHROUGH
+  - ETL_MAYBE_UNUSED
+  - ETL_INLINE_VAR
+  - ETL_ASSUME
+  - ETL_LVALUE_REF_QUALIFIER
+  - ETL_RVALUE_REF_QUALIFIER
+  - ETL_NOEXCEPT
+  - ETL_NOEXCEPT_EXPR
+  - ETL_NOEXCEPT_IF
+  - ETL_NOEXCEPT_FROM
 
-ConstructorInitializerAllOnOneLineOrOnePerLine: 'true'
-ConstructorInitializerIndentWidth: '2'
+Macros:
+  - ETL_NORETURN=[[noreturn]]
+  - ETL_FINAL=final
+  - ETL_OVERRIDE=override
+  - ETL_EXPLICIT=explicit
+  - ETL_DELETE=delete
+  - ETL_CONSTANT=const
+  - ETL_CONSTEXPR=constexpr
+  - ETL_CONSTEXPR11=constexpr
+  - ETL_CONSTEXPR14=constexpr
+  - ETL_CONSTEXPR17=constexpr
+  - ETL_CONSTEXPR20=constexpr
+  - ETL_CONSTEXPR23=constexpr
+  - ETL_CONSTEVAL=consteval
+  - ETL_NODISCARD=[[nodiscard]]
+  - ETL_NORETURN=[[noreturn]]
+  - ETL_DEPRECATED=[[deprecated]]
+#  - ETL_DEPRECATED_REASON=[[deprecated(%0)]] # Hangs with clang-format 18
+  - ETL_LIKELY=[[likely]]
+  - ETL_UNLIKELY=[[unlikely]]
+  - ETL_FALLTHROUGH=[[fallthrough]]
+  - ETL_MAYBE_UNUSED=[[maybe_unused]]
+  - ETL_INLINE_VAR=inline
+  - ETL_ASSUME=[[assume(&0)]]
+  - ETL_LVALUE_REF_QUALIFIER=&
+  - ETL_RVALUE_REF_QUALIFIER=&&
+  - ETL_NOEXCEPT=noexcept
+#  - ETL_NOEXCEPT_EXPR=noexcept(&0)) # Hangs with clang-format 18
+#  - ETL_NOEXCEPT_IF=noexcept(&0)    # Hangs with clang-format 18
+#  - ETL_NOEXCEPT_FROM=noexcept(&0)  # Hangs with clang-format 18
 
-NamespaceIndentation: All
-IndentPPDirectives: BeforeHash
-PointerAlignment: Left
-ColumnLimit: '0'
-ContinuationIndentWidth: '2'
-UseTab: Never
-TabWidth: '2'
-IndentWidth: '2'
-AccessModifierOffset : '-2'
-IndentCaseLabels: false
-Cpp11BracedListStyle: 'true'
-AlignAfterOpenBracket: Align
-AlignConsecutiveDeclarations: true
+# Macros that behave like type names
+TypenameMacros:
+  - ETL_OR_STD
 
-#------------------------------------
-# Configurations not supported by clang-format v12
-#------------------------------------
-# BreakInheritanceList: AfterComma
-# EmptyLineBeforeAccessModifier: Always
-# EmptyLineAfterAccessModifier: Always
-# ReferenceAlignment: Left
-
-...
+# Do not reformat these macros — they contain DSL-like content
+WhitespaceSensitiveMacros:
+  - ETL_ERROR_TEXT
+  - ETL_DECLARE_ENUM_TYPE
+  - ETL_ENUM_TYPE
+  - ETL_END_ENUM_TYPE

.clang-tidy

@@ -0,0 +1,182 @@
+---
+# TODO: Enable these checks in smaller steps
+# cppcoreguidelines-*,
+# portability-* if needed
+# readability-*, -readability-magic-numbers,
+# misc-*, -misc-no-recursion,
+# modernize-*, -modernize-use-trailing-return-type,
+# performance-*,
+
+Checks: >-
+    cert-*, -cert-dcl37-c, -cert-dcl51-cpp,
+    clang-analyzer-*,
+    bugprone-*,
+    -bugprone-easily-swappable-parameters,
+    cppcoreguidelines-pro-type-vararg,
+    cppcoreguidelines-pro-type-reinterpret-cast,
+    llvm-*,-llvm-header-guard,-llvm-include-order,
+    google-readability-casting
+ExtraArgs: ['-Wno-unknown-warning-option']
+HeaderFileExtensions: ['h', 'hpp']
+HeaderFilterRegex: '.*include/etl/.*'
+ImplementationFileExtensions: ['cpp']
+UseColor: true
+# TODO: Enable these when readability check is enabled
+# CheckOptions :
+#  - key: readability-identifier-naming.AbstractClassCase
+#    value: snake_case
+#  - key: readability-identifier-naming.AbstractClassPrefix
+#    value: I
+#  - key: readability-identifier-naming.AbstractClassSuffix
+#    value: ''
+#  - key: readability-identifier-naming.ClassCase
+#    value: snake_case
+#  - key: readability-identifier-naming.ClassPrefix
+#    value: ''
+#  - key: readability-identifier-naming.ClassSuffix
+#    value: ''
+#  - key: readability-identifier-naming.GlobalConstantCase
+#    value: UPPER_CASE
+#  - key: readability-identifier-naming.GlobalConstantPrefix
+#    value: ''
+#  - key: readability-identifier-naming.GlobalConstantSuffix
+#    value: ''
+#  - key: readability-identifier-naming.ConstantCase
+#    value: snake_case
+#  - key: readability-identifier-naming.ConstantPrefix
+#    value: ''
+#  - key: readability-identifier-naming.ConstantSuffix
+#    value: ''
+#  - key: readability-identifier-naming.ConstantMemberCase
+#    value: snake_case
+#  - key: readability-identifier-naming.ConstantMemberPrefix
+#    value: k
+#  - key: readability-identifier-naming.ConstantMemberSuffix
+#    value: ''
+#  - key: readability-identifier-naming.StaticConstantCase
+#    value: snake_case
+#  - key: readability-identifier-naming.StaticConstantPrefix
+#    value: k
+#  - key: readability-identifier-naming.StaticConstantSuffix
+#    value: ''
+#  - key: readability-identifier-naming.EnumCase
+#    value: snake_case
+#  - key: readability-identifier-naming.EnumPrefix
+#    value: ''
+#  - key: readability-identifier-naming.EnumSuffix
+#    value: ''
+#  - key: readability-identifier-naming.EnumConstantCase
+#    value: snake_case
+#  - key: readability-identifier-naming.EnumConstantPrefix
+#    value: ''
+#  - key: readability-identifier-naming.EnumConstantSuffix
+#    value: ''
+#  - key: readability-identifier-naming.GlobalVariableCase
+#    value: snake_case
+#  - key: readability-identifier-naming.GlobalVariablePrefix
+#    value: g
+#  - key: readability-identifier-naming.GlobalVariableSuffix
+#    value: ''
+#  - key: readability-identifier-naming.LocalVariableCase
+#    value: snake_case
+#  - key: readability-identifier-naming.LocalVariablePrefix
+#    value: ''
+#  - key: readability-identifier-naming.LocalVariableSuffix
+#    value: ''
+#  - key: readability-identifier-naming.StructCase
+#    value: aNy_CasE
+#  - key: readability-identifier-naming.StructPrefix
+#    value: ''
+#  - key: readability-identifier-naming.StructSuffix
+#    value: ''
+#  - key: readability-identifier-naming.FunctionCase
+#    value: snake_case
+#  - key: readability-identifier-naming.FunctionPrefix
+#    value: ''
+#  - key: readability-identifier-naming.FunctionSuffix
+#    value: ''
+#  - key: readability-identifier-naming.MethodCase
+#    value: snake_case
+#  - key: readability-identifier-naming.MethodPrefix
+#    value: ''
+#  - key: readability-identifier-naming.MethodSuffix
+#    value: ''
+#  - key: readability-identifier-naming.ParameterCase
+#    value: snake_case
+#  - key: readability-identifier-naming.PrivateMethodCase
+#    value: snake_case
+#  - key: readability-identifier-naming.PrivateMethodPrefix
+#    value: ''
+#  - key: readability-identifier-naming.PrivateMethodSuffix
+#    value: ''
+#  - key: readability-identifier-naming.PublicMethodCase
+#    value: snake_case
+#  - key: readability-identifier-naming.PublicMethodPrefix
+#    value: ''
+#  - key: readability-identifier-naming.PublicMethodSuffix
+#    value: ''
+#  - key: readability-identifier-naming.MemberCase
+#    value: snake_case
+#  - key: readability-identifier-naming.MemberPrefix
+#    value: _
+#  - key: readability-identifier-naming.MemberSuffix
+#    value: ''
+#  - key: readability-identifier-naming.PrivateMemberCase
+#    value: snake_case
+#  - key: readability-identifier-naming.PrivateMemberPrefix
+#    value: _
+#  - key: readability-identifier-naming.PrivateMemberSuffix
+#    value: ''
+#  - key: readability-identifier-naming.PublicMemberCase
+#    value: snake_case
+#  - key: readability-identifier-naming.PublicMemberPrefix
+#    value: ''
+#  - key: readability-identifier-naming.PublicMemberSuffix
+#    value: ''
+#  - key: readability-identifier-naming.NamespaceCase
+#    value: lower_case
+#  - key: readability-identifier-naming.NamespacePrefix
+#    value: ''
+#  - key: readability-identifier-naming.NamespaceSuffix
+#    value: ''
+#  - key: readability-identifier-naming.InlineNamespaceCase
+#    value: lower_case
+#  - key: readability-identifier-naming.InlineNamespacePrefix
+#    value: ''
+#  - key: readability-identifier-naming.InlineNamespaceSuffix
+#    value: ''
+#  - key: readability-identifier-length.IgnoredParameterNames
+#    value: ^(n|id|a|b|x|y)$
+#  - key: readability-identifier-length.IgnoredLoopCounterNames
+#    value: ^[ijkxy_]$
+#  - key: readability-identifier-naming.GlobalFunctionCase
+#    value: snake_case
+#  - key: readability-identifier-naming.GlobalFunctionPrefix
+#    value: ''
+#  - key: readability-identifier-naming.GlobalFunctionSuffix
+#    value: ''
+#  - key: readability-identifier-naming.TemplateParameterCase
+#    value: CamelCase
+#  - key: readability-identifier-naming.TemplateParameterPrefix
+#    value: ''
+#  - key: readability-identifier-naming.TemplateParameterSuffix
+#    value: ''
+#  - key: readability-identifier-naming.TemplateTemplateParameterCase
+#    value: CamelCase
+#  - key: readability-identifier-naming.TemplateTemplateParameterPrefix
+#    value: 'TPL'
+#  - key: readability-identifier-naming.TemplateTemplateParameterSuffix
+#    value: ''
+#  - key: readability-identifier-naming.TypeTemplateParameterCase
+#    value: CamelCase
+#  - key: readability-identifier-naming.TypeTemplateParameterPrefix
+#    value: 'T'
+#  - key: readability-identifier-naming.TypeTemplateParameterSuffix
+#    value: ''
+#  - key: readability-identifier-naming.ValueTemplateParameterCase
+#    value: UPPER_CASE
+#  - key: readability-identifier-naming.ValueTemplateParameterPrefix
+#    value: ''
+#  - key: readability-identifier-naming.ValueTemplateParameterSuffix
+#    value: ''
+...

.devcontainer/Dockerfile

@@ -1,18 +1,78 @@
-ARG BASE_IMAGE_NAME="clang:latest"
+ARG BASE_IMAGE_NAME="mcr.microsoft.com/devcontainers/cpp:2@sha256:a5eb5a1e9109af88bf82ebb0f71903608a68144851ed1e4b852e31b251ac59c6"
 
 FROM ${BASE_IMAGE_NAME}
 
-ARG REINSTALL_CMAKE_VERSION_FROM_SOURCE="3.31.7"
+ARG DEBIAN_SNAPSHOT="20260223T000000Z"
 
-# Optionally install the cmake for vcpkg
-COPY ./reinstall-cmake.sh /tmp/
+SHELL ["/bin/bash", "-o", "pipefail", "-c"]
 
-RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
-    && apt-get -y install --no-install-recommends \
-        git \
-        wget
+ENV LANG=C.UTF-8 \
+    LC_ALL=C.UTF-8 \
+    TZ=UTC
 
-RUN if [ "${REINSTALL_CMAKE_VERSION_FROM_SOURCE}" != "none" ]; then \
-        chmod +x /tmp/reinstall-cmake.sh && /tmp/reinstall-cmake.sh ${REINSTALL_CMAKE_VERSION_FROM_SOURCE}; \
+RUN set -eux \
+    && export DEBIAN_FRONTEND=noninteractive \
+    && if [[ "${DEBIAN_SNAPSHOT}" != "none" ]]; then \
+        snapshot_main="http://snapshot.debian.org/archive/debian/${DEBIAN_SNAPSHOT}"; \
+        snapshot_security="http://snapshot.debian.org/archive/debian-security/${DEBIAN_SNAPSHOT}"; \
+        if [[ -f /etc/apt/sources.list.d/debian.sources ]]; then \
+            sed -ri "s|^URIs: https?://deb.debian.org/debian$|URIs: ${snapshot_main}|g" /etc/apt/sources.list.d/debian.sources; \
+            sed -ri "s|^URIs: https?://deb.debian.org/debian-security$|URIs: ${snapshot_security}|g" /etc/apt/sources.list.d/debian.sources; \
+        elif [[ -f /etc/apt/sources.list ]] || compgen -G "/etc/apt/sources.list.d/*.list" > /dev/null; then \
+            for list_file in /etc/apt/sources.list /etc/apt/sources.list.d/*.list; do \
+                [[ -f "${list_file}" ]] || continue; \
+                sed -ri "s|https?://deb.debian.org/debian|${snapshot_main}|g" "${list_file}"; \
+                sed -ri "s|https?://security.debian.org/debian-security|${snapshot_security}|g" "${list_file}"; \
+                sed -ri "s|https?://deb.debian.org/debian-security|${snapshot_security}|g" "${list_file}"; \
+            done; \
+        else \
+            echo "ERROR: DEBIAN_SNAPSHOT='${DEBIAN_SNAPSHOT}' is set, but no supported apt source files were found."; \
+            echo "Expected /etc/apt/sources.list.d/debian.sources or one or more .list files under /etc/apt/."; \
+            exit 1; \
+        fi; \
+        printf 'Acquire::Check-Valid-Until "false";\n' > /etc/apt/apt.conf.d/99snapshot; \
     fi \
-    && rm -f /tmp/reinstall-cmake.sh
+    && apt-get update \
+    && apt-get -y install --no-install-recommends \
+        python3-full \
+        python3-pip \
+        python3-cogapp \
+        git \
+        wget \
+        cmake \
+        clang-format \
+        clang-format-18 \
+        lcov \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN set -eux; \
+    VERSION="2.4.1"; \
+    case "$(uname -m)" in \
+        x86_64)  ARCH="amd64"; SHA256="bdaa2c0fbee03e5c2f99e605d9419386ce5d558440baac2017398faada839e04" ;; \
+        aarch64) ARCH="arm64"; SHA256="0a09e1f04a0f8a86fd4e709552613f5d82adf6bc72f0a4b5e217670894e79fbf" ;; \
+        *) echo "Unsupported architecture: $(uname -m)"; exit 1 ;; \
+    esac; \
+    wget -O treefmt.tar.gz "https://github.com/numtide/treefmt/releases/download/v${VERSION}/treefmt_${VERSION}_linux_${ARCH}.tar.gz" \
+    && echo "${SHA256} treefmt.tar.gz" | sha256sum -c \
+    && tar xzf treefmt.tar.gz treefmt \
+    && install -m 755 treefmt /usr/bin/treefmt \
+    && rm treefmt.tar.gz treefmt
+
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
+
+RUN set -eux \
+    && echo "Pip version: " \
+    && pip --version \
+    && echo "Cogapp version: " \
+    && pip show cogapp \
+    && echo "Git version: " \
+    && git --version \
+    && echo "Wget version: " \
+    && wget --version \
+    && echo "Cmake version: " \
+    && cmake --version \
+    && echo "Make version: " \
+    && make --version

.devcontainer/armhf/Dockerfile

@@ -0,0 +1,61 @@
+# armhf Test Environment for ETL
+# Uses QEMU user-mode emulation to run armhf binaries on x64 host
+FROM debian:trixie
+
+# Avoid prompts from apt
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Install QEMU user-mode emulation and armhf cross-compilation tools
+RUN dpkg --add-architecture armhf && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    qemu-user-static \
+    qemu-user \
+    binfmt-support \
+    gcc-arm-linux-gnueabihf \
+    g++-arm-linux-gnueabihf \
+    cmake \
+    make \
+    ninja-build \
+    git \
+    wget \
+    ca-certificates \
+    file \
+    libc6:armhf \
+    libstdc++6:armhf \
+    libatomic1:armhf \
+    && rm -rf /var/lib/apt/lists/*
+
+# Create non-root user with stable UID/GID
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=1000
+
+RUN groupadd --gid ${USER_GID} ${USERNAME} && \
+    useradd --uid ${USER_UID} --gid ${USER_GID} --shell /bin/bash --create-home ${USERNAME}
+
+# Set working directory
+WORKDIR /workspaces/etl
+
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
+
+# Verify QEMU and cross-compilation setup
+RUN echo "=== Host Architecture ===" && \
+    uname -m && \
+    echo "" && \
+    echo "=== armhf Cross Compiler ===" && \
+    arm-linux-gnueabihf-gcc --version && \
+    echo "" && \
+    echo "=== QEMU arm ===" && \
+    qemu-arm-static --version | head -n1
+
+# Ensure workspace directory ownership for non-root user
+RUN mkdir -p /workspaces/etl && chown -R ${USERNAME}:${USERNAME} /workspaces
+
+# Switch to non-root user
+USER ${USERNAME}
+
+# Default command
+CMD ["/bin/bash"]

.devcontainer/armhf/devcontainer.json

@@ -0,0 +1,29 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/cpp
+{
+  "name": "armhf (Debian)",
+  "build": {
+    "dockerfile": "./Dockerfile",
+    "context": "."
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-vscode.cpptools",
+        "ms-vscode.cmake-tools"
+      ],
+      "settings": {
+        "cmake.sourceDirectory": "${workspaceFolder}/test",
+        "cmake.configureArgs": [
+          "-DCMAKE_TOOLCHAIN_FILE=${workspaceFolder}/.devcontainer/armhf/toolchain-armhf.cmake",
+          "-DBUILD_TESTS=ON",
+          "-DNO_STL=OFF",
+          "-DETL_CXX_STANDARD=23"
+        ],
+        "cmake.buildDirectory": "${workspaceFolder}/build-armhf",
+        "cmake.generator": "Ninja"
+      }
+    }
+  },
+  "remoteUser": "root"
+}

.devcontainer/armhf/toolchain-armhf.cmake

@@ -0,0 +1,21 @@
+# CMake toolchain file for armhf cross-compilation
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR arm)
+
+# Specify the cross compiler
+set(CMAKE_C_COMPILER arm-linux-gnueabihf-gcc)
+set(CMAKE_CXX_COMPILER arm-linux-gnueabihf-g++)
+set(CMAKE_AR arm-linux-gnueabihf-ar)
+set(CMAKE_RANLIB arm-linux-gnueabihf-ranlib)
+set(CMAKE_STRIP arm-linux-gnueabihf-strip)
+
+# Search for programs in the build host directories
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+
+# For libraries and headers in the target directories
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+# Set QEMU for running tests
+set(CMAKE_CROSSCOMPILING_EMULATOR /usr/bin/qemu-arm-static CACHE FILEPATH "Path to the emulator for cross-compiled binaries")

.devcontainer/clang10/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:10"
+			"BASE_IMAGE_NAME": "silkeh/clang:10",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang11/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:11"
+			"BASE_IMAGE_NAME": "silkeh/clang:11",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang12/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:12"
+			"BASE_IMAGE_NAME": "silkeh/clang:12",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang13/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:13"
+			"BASE_IMAGE_NAME": "silkeh/clang:13",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang14/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:14"
+			"BASE_IMAGE_NAME": "silkeh/clang:14",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang15/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:15"
+			"BASE_IMAGE_NAME": "silkeh/clang:15",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang16/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:16"
+			"BASE_IMAGE_NAME": "silkeh/clang:16",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang17/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:17"
+			"BASE_IMAGE_NAME": "silkeh/clang:17",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang18/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:18-bullseye"
+			"BASE_IMAGE_NAME": "silkeh/clang:18-bullseye",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang19/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:19-bullseye"
+			"BASE_IMAGE_NAME": "silkeh/clang:19-bullseye",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang20/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:20-bullseye"
+			"BASE_IMAGE_NAME": "silkeh/clang:20-bullseye",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang21/devcontainer.json

@@ -0,0 +1,13 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/cpp
+{
+	"name": "Clang 21",
+	"build": {
+		"dockerfile": "../Dockerfile",
+		"args": {
+			"BASE_IMAGE_NAME": "silkeh/clang:21-bullseye",
+			"DEBIAN_SNAPSHOT": "none"
+		},
+		"context": "../context"
+	}
+}

.devcontainer/clang7/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:7"
+			"BASE_IMAGE_NAME": "silkeh/clang:7",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang8/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:8"
+			"BASE_IMAGE_NAME": "silkeh/clang:8",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/clang9/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "silkeh/clang:9"
+			"BASE_IMAGE_NAME": "silkeh/clang:9",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/context/reinstall-cmake.sh

@@ -1,291 +0,0 @@
-#!/usr/bin/env bash
-
-# For more detailed debugging, uncomment the next line
-# set -x
-
-# Explicitly set CMAKE_VERSION from first argument, default to "none"
-CMAKE_VERSION=${1:-"none"}
-
-# --- Configuration ---
-DOWNLOAD_ATTEMPTS=3
-DOWNLOAD_RETRY_DELAY=5 # seconds
-
-# --- Global Variables ---
-TMP_DIR="" # Initialize TMP_DIR, will be set by mktemp
-# Filenames used within TMP_DIR
-CMAKE_INSTALLER_SCRIPT_LOCAL_NAME="cmake-installer.sh"
-CMAKE_CHECKSUM_FILE_LOCAL_NAME="cmake-checksums.txt"
-# This will be the actual name of the CMake binary, derived from version and arch
-# It's important for matching against the checksum file.
-DERIVED_CMAKE_BINARY_FILENAME=""
-
-# --- Cleanup Function ---
-# This trap will execute on EXIT, ERR, SIGINT, SIGTERM
-# It's crucial for debugging to see the state of TMP_DIR if things go wrong.
-cleanup() {
-    # $? is the exit code of the last command before the trap was triggered
-    # or the argument to exit if the script called exit explicitly.
-    LAST_EXIT_CODE=$?
-    echo # Newline for readability
-
-    # Only proceed with detailed cleanup if TMP_DIR was actually created
-    if [[ -n "${TMP_DIR}" && -d "${TMP_DIR}" ]]; then
-        echo "--- Cleanup: Temporary Directory Inspector (${TMP_DIR}) ---"
-        echo "Listing contents of TMP_DIR:"
-        ls -la "${TMP_DIR}"
-
-        # Check and display checksum file content
-        if [[ -f "${TMP_DIR}/${CMAKE_CHECKSUM_FILE_LOCAL_NAME}" ]]; then
-            echo "--- Content of downloaded checksum file (${CMAKE_CHECKSUM_FILE_LOCAL_NAME}) ---"
-            cat "${TMP_DIR}/${CMAKE_CHECKSUM_FILE_LOCAL_NAME}"
-            echo "--- End of checksum file ---"
-        else
-            echo "Checksum file (${CMAKE_CHECKSUM_FILE_LOCAL_NAME}) not found in TMP_DIR."
-        fi
-
-        # Check and display head of (potentially) installer script
-        # Useful to see if it's an HTML error page
-        if [[ -f "${TMP_DIR}/${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}" ]]; then
-            echo "--- First 10 lines of downloaded installer script (${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}) ---"
-            head -n 10 "${TMP_DIR}/${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}"
-            echo "--- End of installer script head ---"
-        elif [[ -f "${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}" ]]; then
-             # If it was renamed
-            echo "--- First 10 lines of downloaded installer script (${DERIVED_CMAKE_BINARY_FILENAME}) ---"
-            head -n 10 "${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}"
-            echo "--- End of installer script head ---"
-        else
-            echo "Installer script not found in TMP_DIR (checked for ${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME} and ${DERIVED_CMAKE_BINARY_FILENAME})."
-        fi
-
-        echo "Attempting to remove temporary directory: ${TMP_DIR}"
-        rm -Rf "${TMP_DIR}"
-        echo "Temporary directory removed."
-        echo "--- End of Cleanup ---"
-    else
-        echo "--- Cleanup: TMP_DIR was not set or not a directory, no temp files to inspect or clean. ---"
-    fi
-
-    # Ensure the script exits with the LAST_EXIT_CODE observed by the trap
-    # unless it was 0 and the script is exiting due to an explicit non-zero exit.
-    # The 'exit' command within the trap will override the script's natural exit code.
-    # So, if the script was going to exit 0, but cleanup had an issue, this could change it.
-    # However, for debugging an exit code 8, we want to preserve the code that *caused* the trap.
-    echo "Script finished with exit code: ${LAST_EXIT_CODE}."
-    exit "${LAST_EXIT_CODE}"
-}
-trap cleanup EXIT ERR SIGINT SIGTERM
-
-# Immediately turn on `set -e` after trap setup
-set -e
-
-# --- Helper Functions ---
-# Function to download a file with retries and basic validation
-download_file() {
-    local url="$1"
-    local output_filename="$2"
-    local attempts_left=$DOWNLOAD_ATTEMPTS
-    local wget_exit_code=0
-
-    while [ $attempts_left -gt 0 ]; do
-        echo "Downloading: ${url}"
-        echo "Saving to: ${TMP_DIR}/${output_filename}"
-        echo "Attempt $((DOWNLOAD_ATTEMPTS - attempts_left + 1)) of ${DOWNLOAD_ATTEMPTS}..."
-
-        # Use wget with:
-        # -O: specify output file
-        # --timeout: connection/read timeout
-        # --tries: number of retries (wget's own retry, distinct from this loop)
-        # --quiet: suppress normal output, but errors still go to stderr
-        # --show-progress: if not quiet, shows a progress bar (optional)
-        # Using -q for less verbose logs, but on failure, we need to know.
-        wget -O "${TMP_DIR}/${output_filename}" --timeout=30 --tries=1 "${url}"
-        wget_exit_code=$?
-
-        if [ ${wget_exit_code} -eq 0 ]; then
-            echo "Download command successful for ${output_filename}."
-            if [ -s "${TMP_DIR}/${output_filename}" ]; then # -s: file exists and has a size greater than 0
-                # Basic check for common HTML error page indicators
-                # This is a heuristic and might not catch all error pages.
-                if head -n 5 "${TMP_DIR}/${output_filename}" | grep -Eiq '<html|<head|<!doctype html|404 Not Found|Error'; then
-                    echo "WARNING: Downloaded file '${output_filename}' might be an HTML error page."
-                    echo "First 5 lines of ${output_filename}:"
-                    head -n 5 "${TMP_DIR}/${output_filename}"
-                    # Consider this a failure for critical files
-                    return 1 # Treat as failure
-                fi
-                echo "File ${output_filename} downloaded and is not empty."
-                return 0 # Success
-            else
-                echo "ERROR: Downloaded file ${output_filename} is empty."
-                # No need to rm here, loop will retry or fail
-            fi
-        else
-            echo "ERROR: wget failed to download ${url} with exit code ${wget_exit_code}."
-        fi
-
-        attempts_left=$((attempts_left - 1))
-        if [ $attempts_left -gt 0 ]; then
-            echo "Retrying in ${DOWNLOAD_RETRY_DELAY} seconds..."
-            sleep $DOWNLOAD_RETRY_DELAY
-        else
-            echo "ERROR: Failed to download ${url} after ${DOWNLOAD_ATTEMPTS} attempts."
-            return 1 # Explicit failure
-        fi
-    done
-    return 1 # Should be unreachable if loop logic is correct, but as a fallback
-}
-
-# --- Main Script Logic ---
-
-if [ "${CMAKE_VERSION}" = "none" ]; then
-    echo "No CMake version specified by argument, skipping CMake reinstallation."
-    exit 0
-fi
-echo "CMake version to install: ${CMAKE_VERSION}"
-
-# 1. Ensure wget is available
-echo "Checking for wget..."
-if ! command -v wget > /dev/null; then
-    echo "wget not found. Attempting to install wget via apt-get..."
-    if command -v apt-get > /dev/null; then
-        apt-get update -y
-        apt-get install -y --no-install-recommends wget
-        echo "wget installed."
-    else
-        echo "ERROR: apt-get not found. Cannot install wget. Please install wget manually."
-        exit 1
-    fi
-else
-    echo "wget is available."
-fi
-
-# 2. (Optional) Remove existing CMake installed via apt
-echo "Attempting to remove any existing CMake installed via apt..."
-if command -v apt-get > /dev/null; then
-    if dpkg -s cmake &> /dev/null; then # Check if cmake package is actually installed
-        apt-get -y purge --auto-remove cmake
-        echo "cmake package purged."
-    else
-        echo "cmake package not found via dpkg, skipping purge."
-    fi
-else
-    echo "apt-get not found, skipping removal of CMake via apt."
-fi
-
-# 3. Create installation and temporary directories
-echo "Creating CMake installation directory /opt/cmake..."
-mkdir -p /opt/cmake
-
-TMP_DIR=$(mktemp -d -t cmake-install-XXXXXXXXXX)
-echo "Temporary directory created: ${TMP_DIR}"
-# Crucial: subsequent operations needing temp files should happen in or relative to TMP_DIR
-# We will cd into TMP_DIR later, or use full paths like ${TMP_DIR}/filename
-
-# 4. Determine system architecture
-echo "Determining system architecture..."
-architecture=$(dpkg --print-architecture)
-case "${architecture}" in
-    arm64) ARCH="aarch64" ;;
-    amd64) ARCH="x86_64" ;;
-    *)
-        echo "ERROR: Unsupported architecture '${architecture}' reported by dpkg."
-        exit 1
-        ;;
-esac
-echo "Detected architecture: ${architecture} (mapped to CMake arch: ${ARCH})"
-
-# 5. Define CMake download URLs and the filename expected by checksum
-DERIVED_CMAKE_BINARY_FILENAME="cmake-${CMAKE_VERSION}-linux-${ARCH}.sh"
-CMAKE_BINARY_URL="https://github.com/Kitware/CMake/releases/download/v${CMAKE_VERSION}/${DERIVED_CMAKE_BINARY_FILENAME}"
-CMAKE_CHECKSUM_FILE_URL="https://github.com/Kitware/CMake/releases/download/v${CMAKE_VERSION}/cmake-${CMAKE_VERSION}-SHA-256.txt"
-
-# 6. Download CMake binary and checksum file
-echo "--- Downloading Files ---"
-if ! download_file "${CMAKE_BINARY_URL}" "${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}"; then
-    echo "ERROR: Failed to download CMake binary installer. See messages above."
-    exit 1
-fi
-
-if ! download_file "${CMAKE_CHECKSUM_FILE_URL}" "${CMAKE_CHECKSUM_FILE_LOCAL_NAME}"; then
-    echo "ERROR: Failed to download CMake checksum file. See messages above."
-    exit 1
-fi
-echo "Downloads complete."
-echo "--- End of Downloading Files ---"
-echo # Newline for readability
-
-# Before checksum, rename the downloaded installer to its derived name,
-# as the checksum file refers to this specific name.
-echo "Renaming downloaded installer from '${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}' to '${DERIVED_CMAKE_BINARY_FILENAME}' for checksum verification."
-mv "${TMP_DIR}/${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}" "${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}"
-if [ ! -f "${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}" ]; then
-    echo "ERROR: Failed to rename installer script for checksum. File '${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}' does not exist after move."
-    exit 1
-fi
-
-# 7. Verify checksum
-echo "--- Verifying Checksum ---"
-echo "Checksum file is: ${TMP_DIR}/${CMAKE_CHECKSUM_FILE_LOCAL_NAME}"
-echo "Binary file to check is: ${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}"
-
-# Ensure the checksum file actually contains an entry for our binary
-# This is important because the SHA-256.txt file contains checksums for *all* release assets
-echo "Checking if checksum file contains entry for '${DERIVED_CMAKE_BINARY_FILENAME}'..."
-if ! grep -q "${DERIVED_CMAKE_BINARY_FILENAME}" "${TMP_DIR}/${CMAKE_CHECKSUM_FILE_LOCAL_NAME}"; then
-    echo "ERROR: The downloaded checksum file '${CMAKE_CHECKSUM_FILE_LOCAL_NAME}' does NOT contain an entry for '${DERIVED_CMAKE_BINARY_FILENAME}'."
-    echo "This strongly suggests that the CMAKE_VERSION ('${CMAKE_VERSION}') or ARCH ('${ARCH}') is incorrect, or the specified version does not provide a .sh installer for this architecture."
-    echo "Please verify the version and available files at https://github.com/Kitware/CMake/releases/tag/v${CMAKE_VERSION}"
-    exit 1
-fi
-echo "Checksum file contains an entry for '${DERIVED_CMAKE_BINARY_FILENAME}'."
-
-# Perform the checksum. We need to be in the directory where the files are.
-echo "Changing directory to ${TMP_DIR} for checksum verification."
-cd "${TMP_DIR}" # <<<<<<< IMPORTANT: sha256sum -c needs to find files
-
-echo "Verifying checksum of '${DERIVED_CMAKE_BINARY_FILENAME}' using '${CMAKE_CHECKSUM_FILE_LOCAL_NAME}'..."
-# The --ignore-missing flag is good, as the .txt file has many checksums.
-# The --strict flag would cause it to error if there are improperly formatted lines.
-# We rely on the grep check above to ensure our specific file is mentioned.
-if sha256sum -c --ignore-missing "${CMAKE_CHECKSUM_FILE_LOCAL_NAME}"; then
-    echo "Checksum verification successful for '${DERIVED_CMAKE_BINARY_FILENAME}'."
-else
-    SHA_EXIT_CODE=$?
-    echo "ERROR: Checksum verification FAILED for '${DERIVED_CMAKE_BINARY_FILENAME}' with exit code ${SHA_EXIT_CODE}."
-    # Cleanup trap will show file contents.
-    exit 1 # Critical failure
-fi
-echo "--- End of Verifying Checksum ---"
-echo # Newline for readability
-
-# 8. Install CMake
-echo "--- Installing CMake ---"
-echo "Making the CMake installer script '${DERIVED_CMAKE_BINARY_FILENAME}' executable..."
-chmod +x "${DERIVED_CMAKE_BINARY_FILENAME}" # Still in TMP_DIR
-
-echo "Executing CMake installer script: ./${DERIVED_CMAKE_BINARY_FILENAME} --prefix=/opt/cmake --skip-license"
-# Execute the script. If this script exits with 8, this is our culprit.
-if ./"${DERIVED_CMAKE_BINARY_FILENAME}" --prefix=/opt/cmake --skip-license; then
-    echo "CMake installer script executed successfully."
-else
-    INSTALLER_EXIT_CODE=$?
-    echo "ERROR: CMake installer script FAILED with exit code ${INSTALLER_EXIT_CODE}."
-    # This is the most likely place for an exit code 8 if downloads and checksums were okay.
-    # The trap will handle cleanup. The script will exit with INSTALLER_EXIT_CODE due to the trap.
-    exit ${INSTALLER_EXIT_CODE} # Explicitly exit with the installer's code
-fi
-echo "--- End of Installing CMake ---"
-echo # Newline for readability
-
-# 9. Create symlinks
-echo "Creating symbolic links for cmake and ctest in /usr/local/bin/..."
-ln -sf /opt/cmake/bin/cmake /usr/local/bin/cmake
-ln -sf /opt/cmake/bin/ctest /usr/local/bin/ctest
-echo "Symbolic links created."
-
-echo # Newline for readability
-echo "SUCCESS: CMake ${CMAKE_VERSION} installation and setup complete."
-
-# The script will exit with 0 here. The trap will run, see $? is 0, and then exit 0.
-exit 0

.devcontainer/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "./Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "mcr.microsoft.com/devcontainers/cpp:debian-12"
+			"BASE_IMAGE_NAME": "mcr.microsoft.com/devcontainers/cpp:2@sha256:a5eb5a1e9109af88bf82ebb0f71903608a68144851ed1e4b852e31b251ac59c6",
+			"DEBIAN_SNAPSHOT": "20260223T000000Z"
 		},
 		"context": "./context"
 	}

.devcontainer/gcc09/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "gcc:9"
+			"BASE_IMAGE_NAME": "gcc:9",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/gcc10/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "gcc:10"
+			"BASE_IMAGE_NAME": "gcc:10",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/gcc11/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "gcc:11"
+			"BASE_IMAGE_NAME": "gcc:11",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/gcc12/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "gcc:12"
+			"BASE_IMAGE_NAME": "gcc:12",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/gcc13/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "gcc:13"
+			"BASE_IMAGE_NAME": "gcc:13",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/gcc14/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "gcc:14"
+			"BASE_IMAGE_NAME": "gcc:14",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/gcc15/devcontainer.json

@@ -5,7 +5,8 @@
 	"build": {
 		"dockerfile": "../Dockerfile",
 		"args": {
-			"BASE_IMAGE_NAME": "gcc:15"
+			"BASE_IMAGE_NAME": "gcc:15",
+			"DEBIAN_SNAPSHOT": "none"
 		},
 		"context": "../context"
 	}

.devcontainer/i386/Dockerfile

@@ -0,0 +1,61 @@
+# i386 Test Environment for ETL
+# Uses QEMU user-mode emulation to run i386 binaries on x64 host
+FROM debian:trixie
+
+# Avoid prompts from apt
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Install QEMU user-mode emulation and i386 cross-compilation tools
+RUN dpkg --add-architecture i386 && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    qemu-user-static \
+    qemu-user \
+    binfmt-support \
+    gcc-i686-linux-gnu \
+    g++-i686-linux-gnu \
+    cmake \
+    make \
+    ninja-build \
+    git \
+    wget \
+    ca-certificates \
+    file \
+    libc6:i386 \
+    libstdc++6:i386 \
+    libatomic1:i386 \
+    && rm -rf /var/lib/apt/lists/*
+
+# Create non-root user with stable UID/GID
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=1000
+
+RUN groupadd --gid ${USER_GID} ${USERNAME} && \
+    useradd --uid ${USER_UID} --gid ${USER_GID} --shell /bin/bash --create-home ${USERNAME}
+
+# Set working directory
+WORKDIR /workspaces/etl
+
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
+
+# Verify QEMU and cross-compilation setup
+RUN echo "=== Host Architecture ===" && \
+    uname -m && \
+    echo "" && \
+    echo "=== i386 Cross Compiler ===" && \
+    i686-linux-gnu-gcc --version && \
+    echo "" && \
+    echo "=== QEMU i386 ===" && \
+    qemu-i386-static --version | head -n1
+
+# Ensure workspace directory ownership for non-root user
+RUN mkdir -p /workspaces/etl && chown -R ${USERNAME}:${USERNAME} /workspaces
+
+# Switch to non-root user
+USER ${USERNAME}
+
+# Default command
+CMD ["/bin/bash"]

.devcontainer/i386/devcontainer.json

@@ -0,0 +1,29 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/cpp
+{
+  "name": "i386 (Debian)",
+  "build": {
+    "dockerfile": "./Dockerfile",
+    "context": "."
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-vscode.cpptools",
+        "ms-vscode.cmake-tools"
+      ],
+      "settings": {
+        "cmake.sourceDirectory": "${workspaceFolder}/test",
+        "cmake.configureArgs": [
+          "-DCMAKE_TOOLCHAIN_FILE=${workspaceFolder}/.devcontainer/i386/toolchain-i386.cmake",
+          "-DBUILD_TESTS=ON",
+          "-DNO_STL=OFF",
+          "-DETL_CXX_STANDARD=23"
+        ],
+        "cmake.buildDirectory": "${workspaceFolder}/build-i386",
+        "cmake.generator": "Ninja"
+      }
+    }
+  },
+  "remoteUser": "root"
+}

.devcontainer/i386/toolchain-i386.cmake

@@ -0,0 +1,21 @@
+# CMake toolchain file for i386 cross-compilation
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR i386)
+
+# Specify the cross compiler
+set(CMAKE_C_COMPILER i686-linux-gnu-gcc)
+set(CMAKE_CXX_COMPILER i686-linux-gnu-g++)
+set(CMAKE_AR i686-linux-gnu-ar)
+set(CMAKE_RANLIB i686-linux-gnu-ranlib)
+set(CMAKE_STRIP i686-linux-gnu-strip)
+
+# Search for programs in the build host directories
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+
+# For libraries and headers in the target directories
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+# Set QEMU for running tests
+set(CMAKE_CROSSCOMPILING_EMULATOR /usr/bin/qemu-i386-static CACHE FILEPATH "Path to the emulator for cross-compiled binaries")

.devcontainer/powerpc/Dockerfile

@@ -0,0 +1,85 @@
+# powerpc Test Environment for ETL
+# Uses QEMU user-mode emulation to run powerpc binaries on x64 host
+FROM debian:sid-20260406
+
+# Avoid prompts from apt
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Install QEMU user-mode emulation and powerpc cross-compilation tools
+RUN dpkg --add-architecture powerpc && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    binfmt-support \
+    gpg \
+    ca-certificates \
+    cmake \
+    make \
+    ninja-build \
+    git \
+    wget \
+    file \
+    debian-ports-archive-keyring \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN cat <<EOF > /etc/apt/sources.list.d/debian.sources
+Types: deb
+URIs: http://snapshot.debian.org/archive/debian/20260406T000000Z
+Suites: sid
+Components: main
+Signed-By: /usr/share/keyrings/debian-archive-keyring.pgp
+EOF
+
+RUN cat <<EOF > /etc/apt/sources.list.d/powerpc.sources
+Types: deb
+URIs: http://snapshot.debian.org/archive/debian-ports/20260406T000000Z
+Suites: sid
+Components: main
+Architectures: powerpc
+Signed-By: /usr/share/keyrings/debian-ports-archive-keyring.gpg
+EOF
+
+RUN echo 'Acquire::Check-Valid-Until "false";' > /etc/apt/apt.conf.d/99no-check-valid
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    qemu-user-static \
+    qemu-user \
+    gcc-powerpc-linux-gnu \
+    g++-powerpc-linux-gnu \
+    libc6:powerpc \
+    libstdc++6:powerpc \
+    libatomic1:powerpc \
+    && rm -rf /var/lib/apt/lists/*
+
+# Create non-root user with stable UID/GID
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=1000
+
+RUN groupadd --gid ${USER_GID} ${USERNAME} && \
+    useradd --uid ${USER_UID} --gid ${USER_GID} --shell /bin/bash --create-home ${USERNAME}
+
+# Set working directory
+WORKDIR /workspaces/etl
+
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
+
+# Verify QEMU and cross-compilation setup
+RUN echo "=== Host Architecture ===" && \
+    uname -m && \
+    echo "" && \
+    echo "=== powerpc Cross Compiler ===" && \
+    powerpc-linux-gnu-gcc --version && \
+    echo "" && \
+    echo "=== QEMU powerpc ===" && \
+    qemu-ppc-static --version | head -n1
+
+# Ensure workspace directory ownership for non-root user
+RUN mkdir -p /workspaces/etl && chown -R ${USERNAME}:${USERNAME} /workspaces
+
+# Switch to non-root user
+USER ${USERNAME}
+
+# Default command
+CMD ["/bin/bash"]

.devcontainer/powerpc/devcontainer.json

@@ -0,0 +1,29 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/cpp
+{
+  "name": "powerpc (Debian)",
+  "build": {
+    "dockerfile": "./Dockerfile",
+    "context": "."
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-vscode.cpptools",
+        "ms-vscode.cmake-tools"
+      ],
+      "settings": {
+        "cmake.sourceDirectory": "${workspaceFolder}/test",
+        "cmake.configureArgs": [
+          "-DCMAKE_TOOLCHAIN_FILE=${workspaceFolder}/.devcontainer/powerpc/toolchain-powerpc.cmake",
+          "-DBUILD_TESTS=ON",
+          "-DNO_STL=ON",
+          "-DETL_CXX_STANDARD=23"
+        ],
+        "cmake.buildDirectory": "${workspaceFolder}/build-powerpc",
+        "cmake.generator": "Ninja"
+      }
+    }
+  },
+  "remoteUser": "root"
+}

.devcontainer/powerpc/toolchain-powerpc.cmake

@@ -0,0 +1,21 @@
+# CMake toolchain file for powerpc cross-compilation
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR powerpc)
+
+# Specify the cross compiler
+set(CMAKE_C_COMPILER powerpc-linux-gnu-gcc)
+set(CMAKE_CXX_COMPILER powerpc-linux-gnu-g++)
+set(CMAKE_AR powerpc-linux-gnu-ar)
+set(CMAKE_RANLIB powerpc-linux-gnu-ranlib)
+set(CMAKE_STRIP powerpc-linux-gnu-strip)
+
+# Search for programs in the build host directories
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+
+# For libraries and headers in the target directories
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+# Set QEMU for running tests
+set(CMAKE_CROSSCOMPILING_EMULATOR /usr/bin/qemu-ppc CACHE FILEPATH "Path to the emulator for cross-compiled binaries")

.devcontainer/riscv64/Dockerfile

@@ -0,0 +1,61 @@
+# riscv64 Test Environment for ETL
+# Uses QEMU user-mode emulation to run riscv64 binaries on x64 host
+FROM debian:trixie
+
+# Avoid prompts from apt
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Install QEMU user-mode emulation and riscv64 cross-compilation tools
+RUN dpkg --add-architecture riscv64 && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    qemu-user-static \
+    qemu-user \
+    binfmt-support \
+    gcc-riscv64-linux-gnu \
+    g++-riscv64-linux-gnu \
+    cmake \
+    make \
+    ninja-build \
+    git \
+    wget \
+    ca-certificates \
+    file \
+    libc6:riscv64 \
+    libstdc++6:riscv64 \
+    libatomic1:riscv64 \
+    && rm -rf /var/lib/apt/lists/*
+
+# Create non-root user with stable UID/GID
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=1000
+
+RUN groupadd --gid ${USER_GID} ${USERNAME} && \
+    useradd --uid ${USER_UID} --gid ${USER_GID} --shell /bin/bash --create-home ${USERNAME}
+
+# Set working directory
+WORKDIR /workspaces/etl
+
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
+
+# Verify QEMU and cross-compilation setup
+RUN echo "=== Host Architecture ===" && \
+    uname -m && \
+    echo "" && \
+    echo "=== riscv64 Cross Compiler ===" && \
+    riscv64-linux-gnu-gcc --version && \
+    echo "" && \
+    echo "=== QEMU riscv64 ===" && \
+    qemu-riscv64-static --version | head -n1
+
+# Ensure workspace directory ownership for non-root user
+RUN mkdir -p /workspaces/etl && chown -R ${USERNAME}:${USERNAME} /workspaces
+
+# Switch to non-root user
+USER ${USERNAME}
+
+# Default command
+CMD ["/bin/bash"]

.devcontainer/riscv64/devcontainer.json

@@ -0,0 +1,29 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/cpp
+{
+  "name": "riscv64 (Debian)",
+  "build": {
+    "dockerfile": "./Dockerfile",
+    "context": "."
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-vscode.cpptools",
+        "ms-vscode.cmake-tools"
+      ],
+      "settings": {
+        "cmake.sourceDirectory": "${workspaceFolder}/test",
+        "cmake.configureArgs": [
+          "-DCMAKE_TOOLCHAIN_FILE=${workspaceFolder}/.devcontainer/riscv64/toolchain-riscv64.cmake",
+          "-DBUILD_TESTS=ON",
+          "-DNO_STL=OFF",
+          "-DETL_CXX_STANDARD=23"
+        ],
+        "cmake.buildDirectory": "${workspaceFolder}/build-riscv64",
+        "cmake.generator": "Ninja"
+      }
+    }
+  },
+  "remoteUser": "root"
+}

.devcontainer/riscv64/toolchain-riscv64.cmake

@@ -0,0 +1,20 @@
+# CMake toolchain file for riscv64 cross-compilation
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR riscv64)
+
+# Specify the cross compiler
+set(CMAKE_C_COMPILER riscv64-linux-gnu-gcc)
+set(CMAKE_CXX_COMPILER riscv64-linux-gnu-g++)
+set(CMAKE_AR riscv64-linux-gnu-ar)
+set(CMAKE_RANLIB riscv64-linux-gnu-ranlib)
+set(CMAKE_STRIP riscv64-linux-gnu-strip)
+# Search for programs in the build host directories
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+
+# For libraries and headers in the target directories
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+# Set QEMU for running tests
+set(CMAKE_CROSSCOMPILING_EMULATOR /usr/bin/qemu-riscv64-static CACHE FILEPATH "Path to the emulator for cross-compiled binaries")

.devcontainer/run-tests.sh

@@ -0,0 +1,56 @@
+#!/bin/bash
+#
+# Run tests inside the separately created docker container for different hardware architecture
+#
+# Strategy:
+# * Create docker image
+# * Enter image
+# * Cross build tests
+# * Run tests via QEMU
+#
+
+set -e
+
+usage()
+{
+  echo "Usage: run-tests.sh <architecture>"
+  echo "Architecture: armhf|i386|powerpc|riscv64|s390x"
+  echo "(run from project root)"
+}
+
+ARCHLIST="armhf i386 powerpc riscv64 s390x"
+
+if [[ " $ARCHLIST " =~ " $1 " ]] ; then
+  ARCH=$1
+else
+  echo "Unsupported architecture: $1"
+  usage
+  exit 1
+fi
+
+if [ "$2" = "" ] ; then
+  echo "Creating docker image..."
+  docker build -t $ARCH .devcontainer/$ARCH
+
+  echo "Entering container..."
+  docker run -it --rm -v "$PWD":/workspaces/etl -w /workspaces/etl $ARCH /bin/bash .devcontainer/run-tests.sh $ARCH inside_container
+
+elif [ "$2" = "inside_container" ] ; then
+  echo "Cross building tests..."
+  mkdir -p build-$ARCH
+  cd build-$ARCH
+  cmake -DCMAKE_TOOLCHAIN_FILE=../.devcontainer/$ARCH/toolchain-$ARCH.cmake \
+        -DBUILD_TESTS=ON -DNO_STL=ON -DETL_CXX_STANDARD=23 \
+        -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_OPTIMISATION=-O0 -DETL_ENABLE_SANITIZER=OFF -DETL_MESSAGES_ARE_NOT_VIRTUAL=OFF \
+        ../test
+  export CMAKE_BUILD_PARALLEL_LEVEL=$(nproc)
+  cmake --build .
+
+  echo "Running tests via CTest (using QEMU emulator from toolchain)..."
+  ctest -V --output-on-failure
+  echo "Tests successful."
+else
+  echo "Invalid second argument: $2"
+  usage
+  exit 1
+fi

.devcontainer/s390x/Dockerfile

@@ -0,0 +1,61 @@
+# s390x Big-Endian Test Environment for ETL
+# Uses QEMU user-mode emulation to run s390x binaries on x64 host
+FROM debian:trixie
+
+# Avoid prompts from apt
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Install QEMU user-mode emulation and s390x cross-compilation tools
+RUN dpkg --add-architecture s390x && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    qemu-user-static \
+    qemu-user \
+    binfmt-support \
+    gcc-s390x-linux-gnu \
+    g++-s390x-linux-gnu \
+    cmake \
+    make \
+    ninja-build \
+    git \
+    wget \
+    ca-certificates \
+    file \
+    libc6:s390x \
+    libstdc++6:s390x \
+    libatomic1:s390x \
+    && rm -rf /var/lib/apt/lists/*
+
+# Create non-root user with stable UID/GID
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=1000
+
+RUN groupadd --gid ${USER_GID} ${USERNAME} && \
+    useradd --uid ${USER_UID} --gid ${USER_GID} --shell /bin/bash --create-home ${USERNAME}
+
+# Set working directory
+WORKDIR /workspaces/etl
+
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
+
+# Verify QEMU and cross-compilation setup
+RUN echo "=== Host Architecture ===" && \
+    uname -m && \
+    echo "" && \
+    echo "=== s390x Cross Compiler ===" && \
+    s390x-linux-gnu-gcc --version && \
+    echo "" && \
+    echo "=== QEMU s390x ===" && \
+    qemu-s390x-static --version | head -n1
+
+# Ensure workspace directory ownership for non-root user
+RUN mkdir -p /workspaces/etl && chown -R ${USERNAME}:${USERNAME} /workspaces
+
+# Switch to non-root user
+USER ${USERNAME}
+
+# Default command
+CMD ["/bin/bash"]

.devcontainer/s390x/devcontainer.json

@@ -0,0 +1,29 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/cpp
+{
+  "name": "s390x Big Endian (Debian)",
+  "build": {
+    "dockerfile": "./Dockerfile",
+    "context": "."
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-vscode.cpptools",
+        "ms-vscode.cmake-tools"
+      ],
+      "settings": {
+        "cmake.sourceDirectory": "${workspaceFolder}/test",
+        "cmake.configureArgs": [
+          "-DCMAKE_TOOLCHAIN_FILE=${workspaceFolder}/.devcontainer/s390x/toolchain-s390x.cmake",
+          "-DBUILD_TESTS=ON",
+          "-DNO_STL=OFF",
+          "-DETL_CXX_STANDARD=23"
+        ],
+        "cmake.buildDirectory": "${workspaceFolder}/build-s390x",
+        "cmake.generator": "Ninja"
+      }
+    }
+  },
+  "remoteUser": "root"
+}

.devcontainer/s390x/toolchain-s390x.cmake

@@ -0,0 +1,21 @@
+# CMake toolchain file for s390x cross-compilation
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR s390x)
+
+# Specify the cross compiler
+set(CMAKE_C_COMPILER s390x-linux-gnu-gcc)
+set(CMAKE_CXX_COMPILER s390x-linux-gnu-g++)
+set(CMAKE_AR s390x-linux-gnu-ar)
+set(CMAKE_RANLIB s390x-linux-gnu-ranlib)
+set(CMAKE_STRIP s390x-linux-gnu-strip)
+
+# Search for programs in the build host directories
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+
+# For libraries and headers in the target directories
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+# Set QEMU for running tests
+set(CMAKE_CROSSCOMPILING_EMULATOR /usr/bin/qemu-s390x-static CACHE FILEPATH "Path to the emulator for cross-compiled binaries")

.devcontainer/ubuntu-26.04/Dockerfile

@@ -0,0 +1,20 @@
+FROM ubuntu:26.04
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update && apt-get install -y \
+    build-essential \
+    cmake \
+    git \
+    ninja-build \
+    python3 \
+    python3-pip \
+    clang \
+    docker.io \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN useradd -m -s /bin/bash vscode
+
+WORKDIR /etl
+
+CMD ["/bin/bash"]

.github/workflows/bazel-gcc-c++23-no-stl.yml

@@ -0,0 +1,22 @@
+name: bazel-gcc-c++23-no-stl
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-bazel-gcc-cpp23-no-stl:
+    name: Bazel GCC C++23 Linux - No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build
+      run: bazel build //test:etl_tests --cxxopt=-std=c++23 --copt=-DETL_NO_STL
+
+    - name: Run tests
+      run: bazel test //test:etl_tests --cxxopt=-std=c++23 --copt=-DETL_NO_STL --test_output=all

.github/workflows/clang-c++11.yml

@@ -3,7 +3,7 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
     types: [opened, synchronize, reopened]
 
 jobs:
@@ -25,10 +25,10 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp11-linux-no-stl:
     name: Clang C++11 Linux - No STL
@@ -47,7 +47,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v

.github/workflows/clang-c++14.yml

@@ -3,7 +3,7 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
     types: [opened, synchronize, reopened]
 
 jobs:
@@ -25,10 +25,10 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp14-linux-no-stl:
     name: Clang C++14 Linux - No STL
@@ -47,7 +47,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v

.github/workflows/clang-c++17.yml

@@ -3,7 +3,7 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
     types: [opened, synchronize, reopened]
 
 jobs:
@@ -25,10 +25,10 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp17-linux-no-stl:
     name: Clang C++17 Linux - No STL
@@ -47,7 +47,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v

.github/workflows/clang-c++20.yml

@@ -3,7 +3,7 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
     types: [opened, synchronize, reopened]
 
 jobs:
@@ -32,10 +32,10 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./
         clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp20-linux-stl-force-cpp03:
     name: Clang C++20 Linux - STL - Force C++03
@@ -61,10 +61,10 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp20-linux-no-stl-force-cpp03:
     name: Clang C++20 Linux - No STL - Force C++03
@@ -90,17 +90,17 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp20-osx-stl:
     name: Clang C++20 OSX - STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-13]
+        os: [macos-15]
 
     steps:
     - uses: actions/checkout@v4
@@ -112,17 +112,17 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp20-osx-no-stl:
     name: Clang C++20 OSX - No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-13]
+        os: [macos-15]
 
     steps:
     - uses: actions/checkout@v4
@@ -134,17 +134,17 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp20-osx-stl-force-cpp03:
     name: Clang C++20 OSX - STL - Force C++03
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-13]
+        os: [macos-15]
 
     steps:
     - uses: actions/checkout@v4
@@ -156,17 +156,17 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp20-osx-no-stl-force-cpp03:
     name: Clang C++20 OSX - No STL - Force C++03
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-13]
+        os: [macos-15]
 
     steps:
     - uses: actions/checkout@v4
@@ -178,8 +178,8 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 

.github/workflows/clang-c++23.yml

@@ -3,7 +3,8 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
 
 jobs:
 
@@ -12,94 +13,73 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
 
-    # Temporary fix. See https://github.com/actions/runner-images/issues/8659
-    - name: Install newer Clang
-      run: |
-        wget https://apt.llvm.org/llvm.sh
-        chmod +x ./llvm.sh
-        sudo ./llvm.sh 17
-
     - name: Build
       run: |
-        export CC=clang-17
-        export CXX=clang++-17
+        export CC=clang
+        export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=OFF -DETL_CXX_STANDARD=23 ./
-        clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp23-linux-stl-force-cpp03:
     name: Clang C++23 Linux - STL - Force C++03
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
 
-    # Temporary fix. See https://github.com/actions/runner-images/issues/8659
-    - name: Install newer Clang
-      run: |
-        wget https://apt.llvm.org/llvm.sh
-        chmod +x ./llvm.sh
-        sudo ./llvm.sh 17
-
     - name: Build
       run: |
-        export CC=clang-17
-        export CXX=clang++-17
+        export CC=clang
+        export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
-        clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp2-linux-no-stl-force-cpp03:
     name: Clang C++23 Linux - No STL - Force C++03
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
 
-    # Temporary fix. See https://github.com/actions/runner-images/issues/8659
-    - name: Install newer Clang
-      run: |
-        wget https://apt.llvm.org/llvm.sh
-        chmod +x ./llvm.sh
-        sudo ./llvm.sh 17
-
     - name: Build
       run: |
-        export CC=clang-17
-        export CXX=clang++-17
+        export CC=clang
+        export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
-        clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp23-osx-stl:
     name: Clang C++23 OSX - STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-13]
+        os: [macos-15]
 
     steps:
     - uses: actions/checkout@v4
@@ -109,19 +89,19 @@ jobs:
         export CC=clang
         export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=OFF -DETL_CXX_STANDARD=23 ./
+        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp23-osx-no-stl:
     name: Clang C++23 OSX - No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-13]
+        os: [macos-15]
 
     steps:
     - uses: actions/checkout@v4
@@ -131,19 +111,19 @@ jobs:
         export CC=clang
         export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=OFF -DETL_CXX_STANDARD=23 ./
+        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp23-osx-stl-force-cpp03:
     name: Clang C++23 OSX - STL - Force C++03
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-13]
+        os: [macos-15]
 
     steps:
     - uses: actions/checkout@v4
@@ -153,19 +133,19 @@ jobs:
         export CC=clang
         export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
+        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-clang-cpp23-osx-no-stl-force-cpp03:
     name: Clang C++23 OSX - No STL - Force C++03
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-13]
+        os: [macos-15]
 
     steps:
     - uses: actions/checkout@v4
@@ -175,10 +155,10 @@ jobs:
         export CC=clang
         export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
+        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 

.github/workflows/clang-c++26.yml

@@ -0,0 +1,185 @@
+name: clang-c++26
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-clang-cpp26-linux-stl:
+    name: Clang C++26 Linux - STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./ && \
+          clang --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-clang-cpp26-linux-no-stl:
+    name: Clang C++26 Linux - No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./ && \
+          clang --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-clang-cpp26-linux-stl-force-cpp03:
+    name: Clang C++26 Linux - STL - Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./ && \
+          clang --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-clang-cpp26-linux-no-stl-force-cpp03:
+    name: Clang C++26 Linux - No STL - Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./ && \
+          clang --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-clang-cpp26-osx-stl:
+    name: Clang C++26 OSX - STL
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-26]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build
+      run: |
+        export CC=clang
+        export CXX=clang++
+        export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
+        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+    - name: Run tests
+      run: ./test/etl_tests -v
+
+  build-clang-cpp26-osx-no-stl:
+    name: Clang C++26 OSX - No STL
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-26]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build
+      run: |
+        export CC=clang
+        export CXX=clang++
+        export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
+        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+    - name: Run tests
+      run: ./test/etl_tests -v
+
+  build-clang-cpp26-osx-stl-force-cpp03:
+    name: Clang C++26 OSX - STL - Force C++03
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-26]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build
+      run: |
+        export CC=clang
+        export CXX=clang++
+        export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
+        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+    - name: Run tests
+      run: ./test/etl_tests -v
+
+  build-clang-cpp26-osx-no-stl-force-cpp03:
+    name: Clang C++26 OSX - No STL - Force C++03
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-26]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build
+      run: |
+        export CC=clang
+        export CXX=clang++
+        export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
+        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+    - name: Run tests
+      run: ./test/etl_tests -v

.github/workflows/clang-format.yaml

@@ -0,0 +1,43 @@
+name: clang-format
+
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+  clang-format:
+    name: clang-format
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Install clang-format and git
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends git clang-format
+          clang-format --version
+
+      - name: Run clang-format on added/changed files
+        run: |
+          if [ "${{ github.event_name }}" = "pull_request" ]; then
+            BEFORE="origin/${{ github.base_ref }}"
+          elif [ "${{ github.event_name }}" = "push" ]; then
+            BEFORE="${{ github.event.before }}"
+          else
+            echo "Unsupported event: ${{ github.event_name }}"
+            echo "This is likely a bug in the workflow configuration. Please report it to the maintainers."
+            exit 1
+          fi
+
+          git diff --name-only -z --diff-filter=AMCR "$BEFORE"..HEAD -- \
+            '*.c' '*.cc' '*.cxx' '*.cpp' \
+            '*.h' '*.hh' '*.hpp' '*.hxx' \
+            '*.ipp' '*.inl' \
+            ':(exclude)include/etl/generators/*' \
+            ':(exclude)include/etl/private/*_cpp03.h' \
+            | xargs -0 --no-run-if-empty clang-format --Werror -n --style=file

.github/workflows/clang-format_update.yaml

@@ -0,0 +1,21 @@
+name: clang-format-update
+
+on:
+  workflow_dispatch:
+
+jobs:
+  clang-format:
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install clang-format
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends clang-format
+          clang-format --version
+
+      - name: Run clang-format
+        run: |
+          find . \( -name '*.cpp' -o -name '*.h' -o -name '*.c' \) | xargs clang-format --dry-run --Werror

.github/workflows/clang-syntax-checks.yml

@@ -3,7 +3,7 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
     types: [opened, synchronize, reopened]
 
 jobs:
@@ -23,10 +23,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=03 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp03-linux-No-STL:
-    name: Syntax Check - Clang C++03 Linux No STL 
+    name: Syntax Check - Clang C++03 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -41,7 +41,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=03 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp11-linux-STL:
     name: Syntax Check - Clang C++11 Linux STL
@@ -59,10 +59,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp11-linux-No-STL:
-    name: Syntax Check - Clang C++11 Linux No STL 
+    name: Syntax Check - Clang C++11 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -77,7 +77,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp11-linux-STL-Force-CPP03:
     name: Syntax Check - Clang C++11 Linux STL Force C++03
@@ -95,7 +95,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=11 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp11-linux-No-STL-Force-CPP03:
     name: Syntax Check - Clang C++11 Linux No STL Force C++03
@@ -113,7 +113,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=11 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp14-linux-STL:
     name: Syntax Check - Clang C++14 Linux STL
@@ -131,10 +131,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp14-linux-No-STL:
-    name: Syntax Check - Clang C++14 Linux No STL 
+    name: Syntax Check - Clang C++14 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -149,7 +149,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp14-linux-STL-Force-CPP03:
     name: Syntax Check - Clang C++14 Linux STL Force C++03
@@ -167,7 +167,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=14 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp14-linux-No-STL-Force-CPP03:
     name: Syntax Check - Clang C++14 Linux No STL Force C++03
@@ -185,7 +185,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=14 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp17-linux-STL:
     name: Syntax Check - Clang C++17 Linux STL
@@ -203,10 +203,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp17-linux-No-STL:
-    name: Syntax Check - Clang C++17 Linux No STL 
+    name: Syntax Check - Clang C++17 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -221,7 +221,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp17-linux-STL-Force-CPP03:
     name: Syntax Check - Clang C++17 Linux STL Force C++03
@@ -239,7 +239,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=17 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp17-linux-No-STL-Force-CPP03:
     name: Syntax Check - Clang C++17 Linux No STL Force C++03
@@ -257,7 +257,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=17 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp20-linux-STL:
     name: Syntax Check - Clang C++20 Linux STL
@@ -275,10 +275,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp20-linux-No-STL:
-    name: Syntax Check - Clang C++20 Linux No STL 
+    name: Syntax Check - Clang C++20 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -293,7 +293,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp20-linux-STL-Force-CPP03:
     name: Syntax Check - Clang C++20 Linux STL Force C++03
@@ -311,7 +311,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp20-linux-No-STL-Force-CPP03:
     name: Syntax Check - Clang C++20 Linux No STL Force C++03
@@ -329,7 +329,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp23-linux-STL:
     name: Syntax Check - Clang C++23 Linux STL
@@ -347,10 +347,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp23-linux-No-STL:
-    name: Syntax Check - Clang C++23 Linux No STL 
+    name: Syntax Check - Clang C++23 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -365,7 +365,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp23-linux-STL-Force-CPP03:
     name: Syntax Check - Clang C++23 Linux STL Force C++03
@@ -383,7 +383,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp23-linux-No-STL-Force-CPP03:
     name: Syntax Check - Clang C++23 Linux No STL Force C++03
@@ -401,4 +401,84 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+  build-clang-cpp26-linux-STL:
+    name: Syntax Check - Clang C++26 Linux STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          clang++ --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-clang-cpp26-linux-No-STL:
+    name: Syntax Check - Clang C++26 Linux No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          clang++ --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-clang-cpp26-linux-STL-Force-CPP03:
+    name: Syntax Check - Clang C++26 Linux STL Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          clang++ --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-clang-cpp26-linux-No-STL-Force-CPP03:
+    name: Syntax Check - Clang C++26 Linux No STL Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          clang++ --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"

.github/workflows/clang-tidy.yaml

@@ -0,0 +1,29 @@
+name: clang-tidy
+
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+  clang-tidy:
+    name: clang-tidy
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Install dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends clang clang-tidy
+          clang --version
+          clang-tidy --version
+          run-clang-tidy --version || true
+
+      - name: Run clang-tidy
+        run: |
+          test/run-clang-tidy.sh

.github/workflows/coverage.yml

@@ -0,0 +1,68 @@
+name: coverage
+
+on:
+  push:
+    branches: [ master, pull-request/* ]
+  pull_request:
+    branches: [ master, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+# Allow only one concurrent deployment to GitHub Pages
+concurrency:
+  group: coverage-${{ github.ref }}
+  cancel-in-progress: true
+
+# Grant GITHUB_TOKEN the minimum permissions needed at the workflow level
+permissions:
+  contents: read
+
+jobs:
+
+  coverage:
+    name: Generate Coverage Report
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Install dependencies
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y lcov llvm gcc g++ clang cmake
+
+    - name: Build, test, and collect coverage
+      run: |
+        cd test
+        ./run-coverage.sh
+
+    - name: Upload coverage report artifact
+      uses: actions/upload-artifact@v4
+      with:
+        name: coverage-report
+        path: test/build-coverage/coverage/
+        retention-days: 30
+
+    - name: Upload Pages artifact
+      if: github.event_name == 'push' && github.ref == 'refs/heads/master'
+      uses: actions/upload-pages-artifact@v3
+      with:
+        path: test/build-coverage/coverage/
+
+  deploy-pages:
+    name: Deploy to GitHub Pages
+    if: github.event_name == 'push' && github.ref == 'refs/heads/master'
+    needs: coverage
+    runs-on: ubuntu-22.04
+
+    permissions:
+      pages: write
+      id-token: write
+
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+
+    steps:
+    - name: Deploy to GitHub Pages
+      id: deployment
+      uses: actions/deploy-pages@v5

.github/workflows/gcc-c++11.yml

@@ -3,7 +3,7 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
     types: [opened, synchronize, reopened]
 
 jobs:
@@ -26,10 +26,10 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-gcc-cpp11-linux-no-stl:
     name: GCC C++11 Linux - No STL
@@ -49,7 +49,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v

.github/workflows/gcc-c++14.yml

@@ -3,7 +3,7 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
     types: [opened, synchronize, reopened]
 
 jobs:
@@ -25,10 +25,10 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-gcc-cpp14-linux-no-stl:
     name: GCC C++14 Linux - No STL
@@ -47,7 +47,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v

.github/workflows/gcc-c++17.yml

@@ -3,7 +3,7 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
     types: [opened, synchronize, reopened]
 
 jobs:
@@ -25,10 +25,10 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-gcc-cpp17-linux-no-stl:
     name: GCC C++17 Linux - No STL
@@ -47,7 +47,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v

.github/workflows/gcc-c++20.yml

@@ -3,7 +3,7 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
     types: [opened, synchronize, reopened]
 
 jobs:
@@ -25,10 +25,10 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-gcc-cpp20-linux-no-stl:
     name: GCC C++20 Linux - No STL
@@ -47,10 +47,10 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-gcc-cpp20-linux-stl-force-cpp03:
     name: GCC C++20 Linux - STL - Force C++03
@@ -69,10 +69,10 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-gcc-cpp20-linux-no-stl-force-cpp03:
     name: GCC C++20 Linux - No STL - Force C++03
@@ -91,7 +91,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v

.github/workflows/gcc-c++23-armhf.yml

@@ -0,0 +1,29 @@
+name: gcc-c++23-armhf
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp23-linux-no-stl-armhf:
+    name: GCC C++23 Linux - No STL - armhf
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-armhf -f .devcontainer/armhf/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-armhf bash -c "\
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF \
+           -DETL_CXX_STANDARD=23 -DCMAKE_TOOLCHAIN_FILE=.devcontainer/armhf/toolchain-armhf.cmake \
+           -DEXTRA_TESTING_FLAGS=-v \
+           ./ && \
+          cmake --build . -- -j \$(getconf _NPROCESSORS_ONLN) && \
+          ctest -V"

.github/workflows/gcc-c++23-i386.yml

@@ -0,0 +1,29 @@
+name: gcc-c++23-i386
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp23-linux-no-stl-i386:
+    name: GCC C++23 Linux - No STL - i386
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-i386 -f .devcontainer/i386/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-i386 bash -c "\
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF \
+           -DETL_CXX_STANDARD=23 -DCMAKE_TOOLCHAIN_FILE=.devcontainer/i386/toolchain-i386.cmake \
+           -DEXTRA_TESTING_FLAGS=-v \
+           ./ && \
+          cmake --build . -- -j \$(getconf _NPROCESSORS_ONLN) && \
+          ctest -V"

.github/workflows/gcc-c++23-powerpc.yml

@@ -0,0 +1,29 @@
+name: gcc-c++23-powerpc
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp23-linux-no-stl-powerpc:
+    name: GCC C++23 Linux - No STL - powerpc
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-powerpc -f .devcontainer/powerpc/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-powerpc bash -c "\
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF \
+           -DETL_CXX_STANDARD=23 -DCMAKE_TOOLCHAIN_FILE=.devcontainer/powerpc/toolchain-powerpc.cmake \
+           -DEXTRA_TESTING_FLAGS=-v \
+           ./ && \
+          cmake --build . -- -j \$(getconf _NPROCESSORS_ONLN) && \
+          ctest -V"

.github/workflows/gcc-c++23-riscv64.yml

@@ -0,0 +1,29 @@
+name: gcc-c++23-riscv64
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp23-linux-no-stl-riscv64:
+    name: GCC C++23 Linux - No STL - riscv64
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-riscv64 -f .devcontainer/riscv64/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-riscv64 bash -c "\
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF \
+           -DETL_CXX_STANDARD=23 -DCMAKE_TOOLCHAIN_FILE=.devcontainer/riscv64/toolchain-riscv64.cmake \
+           -DEXTRA_TESTING_FLAGS=-v \
+           ./ && \
+          cmake --build . -- -j \$(getconf _NPROCESSORS_ONLN) && \
+          ctest -V"

.github/workflows/gcc-c++23-s390x.yml

@@ -0,0 +1,29 @@
+name: gcc-c++23-s390x
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp23-linux-no-stl-s390x:
+    name: GCC C++23 Linux - No STL - s390x
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-s390x -f .devcontainer/s390x/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-s390x bash -c "\
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF \
+           -DETL_CXX_STANDARD=23 -DCMAKE_TOOLCHAIN_FILE=.devcontainer/s390x/toolchain-s390x.cmake \
+           -DEXTRA_TESTING_FLAGS=-v \
+           ./ && \
+          cmake --build . -- -j \$(getconf _NPROCESSORS_ONLN) && \
+          ctest -V"

.github/workflows/gcc-c++23.yml

@@ -3,7 +3,8 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
 
 jobs:
 
@@ -12,7 +13,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
@@ -22,19 +23,19 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         export CC=gcc
         export CXX=g++
-        cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=OFF -DETL_CXX_STANDARD=23 ./
+        cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-gcc-cpp23-linux-no-stl:
     name: GCC C++23 Linux - No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
@@ -44,19 +45,19 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         export CC=gcc
         export CXX=g++
-        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=OFF -DETL_CXX_STANDARD=23 ./
+        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-gcc-cpp23-linux-stl-force-cpp03:
     name: GCC C++23 Linux - STL - Force C++03
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
@@ -66,19 +67,19 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         export CC=gcc
         export CXX=g++
-        cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
+        cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v
 
   build-gcc-cpp23-linux-no-stl-force-cpp03:
     name: GCC C++23 Linux - No STL - Force C++03
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
@@ -88,9 +89,9 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         export CC=gcc
         export CXX=g++
-        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
+        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
-      run: ./test/etl_tests
+      run: ./test/etl_tests -v

.github/workflows/gcc-c++26.yml

@@ -0,0 +1,97 @@
+name: gcc-c++26
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp26-linux-stl:
+    name: GCC C++26 Linux - STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./ && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-gcc-cpp26-linux-no-stl:
+    name: GCC C++26 Linux - No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./ && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-gcc-cpp26-linux-stl-force-cpp03:
+    name: GCC C++26 Linux - STL - Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./ && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-gcc-cpp26-linux-no-stl-force-cpp03:
+    name: GCC C++26 Linux - No STL - Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./ && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"

.github/workflows/gcc-syntax-checks.yml

@@ -3,7 +3,7 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
     types: [opened, synchronize, reopened]
 
 jobs:
@@ -23,10 +23,10 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=03 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp03-linux-No-STL:
-    name: Syntax Check - GCC C++03 Linux No STL 
+    name: Syntax Check - GCC C++03 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -41,7 +41,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=03 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp11-linux-STL:
     name: Syntax Check - GCC C++11 Linux STL
@@ -59,7 +59,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp11-linux-No-STL:
     name: Syntax Check - GCC C++11 Linux No STL 
@@ -77,7 +77,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp11-linux-STL-Force-CPP03:
     name: Syntax Check - GCC C++11 Linux STL Force C++03
@@ -95,7 +95,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=11 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp11-linux-No-STL-Force-CPP03:
     name: Syntax Check - GCC C++11 Linux No STL Force C++03
@@ -113,7 +113,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=11 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp14-linux-STL:
     name: Syntax Check - GCC C++14 Linux STL
@@ -131,7 +131,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp14-linux-No-STL:
     name: Syntax Check - GCC C++14 Linux No STL 
@@ -149,7 +149,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp14-linux-STL-Force-CPP03:
     name: Syntax Check - GCC C++14 Linux STL Force C++03
@@ -167,7 +167,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=14 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp14-linux-No-STL-Force-CPP03:
     name: Syntax Check - GCC C++14 Linux No STL Force C++03
@@ -185,7 +185,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=14 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp17-linux-STL:
     name: Syntax Check - GCC C++17 Linux STL
@@ -203,7 +203,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp17-linux-No-STL:
     name: Syntax Check - GCC C++17 Linux No STL 
@@ -221,7 +221,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp17-linux-STL-Force-CPP03:
     name: Syntax Check - GCC C++17 Linux STL Force C++03
@@ -239,7 +239,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=17 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp17-linux-No-STL-Force-CPP03:
     name: Syntax Check - GCC C++17 Linux No STL Force C++03
@@ -257,7 +257,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=17 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp20-linux-STL:
     name: Syntax Check - GCC C++20 Linux STL
@@ -275,7 +275,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp20-linux-No-STL:
     name: Syntax Check - GCC C++20 Linux No STL 
@@ -293,7 +293,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp20-linux-STL-Force-CPP03:
     name: Syntax Check - GCC C++20 Linux STL Force C++03
@@ -311,7 +311,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp20-linux-No-STL-Force-CPP03:
     name: Syntax Check - GCC C++20 Linux No STL Force C++03
@@ -329,7 +329,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp23-linux-STL:
     name: Syntax Check - GCC C++23 Linux STL
@@ -347,7 +347,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp23-linux-No-STL:
     name: Syntax Check - GCC C++23 Linux No STL 
@@ -365,7 +365,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp23-linux-STL-Force-CPP03:
     name: Syntax Check - GCC C++23 Linux STL Force C++03
@@ -383,7 +383,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp23-linux-No-STL-Force-CPP03:
     name: Syntax Check - GCC C++23 Linux No STL Force C++03
@@ -401,4 +401,84 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+  build-gcc-cpp26-linux-STL:
+    name: Syntax Check - GCC C++26 Linux STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-gcc-cpp26-linux-No-STL:
+    name: Syntax Check - GCC C++26 Linux No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-gcc-cpp26-linux-STL-Force-CPP03:
+    name: Syntax Check - GCC C++26 Linux STL Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-gcc-cpp26-linux-No-STL-Force-CPP03:
+    name: Syntax Check - GCC C++26 Linux No STL Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"

.github/workflows/generator.yml

@@ -0,0 +1,24 @@
+name: generator checks
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+  generator-run:
+    name: Header Generator
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Install dependencies
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y python3-cogapp
+
+    - name: Run generator_test.py
+      run: |
+        cd scripts && python3 generator_test.py

.github/workflows/meson-gcc-c++23-no-stl.yml

@@ -0,0 +1,31 @@
+name: meson-gcc-c++23-no-stl
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-meson-gcc-cpp23-no-stl:
+    name: Meson GCC C++23 Linux - No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v6
+
+    - name: Install Meson
+      run: sudo apt-get install -y meson
+
+    - name: Configure
+      run: |
+        export CC=gcc
+        export CXX=g++
+        meson setup builddir -Duse_stl=false -Dcpp_std=c++23
+
+    - name: Build
+      run: meson compile -C builddir
+
+    - name: Run tests
+      run: meson test -C builddir -v

.github/workflows/msvc.yml

@@ -3,7 +3,7 @@ on:
   push:
     branches: [ master, development, pull-request/* ]
   pull_request:
-    branches: [ master, pull-request/* ]
+    branches: [ master, development, pull-request/* ]
     types: [opened, synchronize, reopened]
 
 jobs:
@@ -22,12 +22,12 @@ jobs:
 
     - name: Build
       run: |
-        cmake -G "Visual Studio 17 2022" -AWin32 -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./
+        cmake -G "Visual Studio 17 2022" -AWin32 -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./
         MSBuild.exe -version
         MSBuild.exe .\etl.sln
         
     - name: Run tests
-      run: test/Debug/etl_tests.exe
+      run: test/Debug/etl_tests.exe -v
 
   build-windows-msvc-no-stl:
     name: Windows - No STL
@@ -48,7 +48,7 @@ jobs:
         MSBuild.exe .\etl.sln
         
     - name: Run tests
-      run: test/Debug/etl_tests.exe
+      run: test/Debug/etl_tests.exe -v
 
   build-windows-msvc-stl-force-cpp03:
     name: Windows - STL - Force C++03
@@ -70,7 +70,7 @@ jobs:
         MSBuild.exe .\etl.sln
 
     - name: Run tests
-      run: test/Debug/etl_tests.exe
+      run: test/Debug/etl_tests.exe -v
         
   build-windows-msvc-no-stl-force-cpp03:
     name: Windows - No STL - Force C++03
@@ -92,5 +92,5 @@ jobs:
         MSBuild.exe .\etl.sln
 
     - name: Run tests
-      run: test/Debug/etl_tests.exe
+      run: test/Debug/etl_tests.exe -v
 

.gitignore

@@ -3,6 +3,8 @@
 ## Personal
 #################
 docs/html
+hugo/public
+hugo/.hugo_build.lock
 include/etl/html/
 include/etl/latex/
 test/vs2013/Debug
@@ -411,3 +413,9 @@ examples/UniquePtrWithPool/UniquePtrWithPool
 test/vs2022/Debug Clang C++20 - Optimised -O2
 include/etl/header_file_list.txt
 temp
+test/syntax_check/build-make
+hugo/public
+hugo/resources
+hugo/.hugo_build.lock
+docs/*.html
+test/build-coverage

.treefmt.toml

@@ -0,0 +1,45 @@
+[global]
+excludes = [
+  "**/Doxyfile",
+  "**/Makefile",
+  "*.*-format",
+  "*.S",
+  "*.cmm",
+  "*.css",
+  "*.dld",
+  "*.gdb",
+  "*.gif",
+  "*.gitignore",
+  "*.html",
+  "*.ini",
+  "*.josh",
+  "*.json",
+  "*.md",
+  "*.png",
+  "*.puml",
+  "*.py",
+  "*.rb",
+  "*.rst",
+  "*.s",
+  "*.sh",
+  "*.spec",
+  "*.toml",
+  "*.txt",
+  "*.yaml",
+  "*.yml",
+  "docker/**",
+  "temp/**",
+  "scripts/clang-format-wrapper",
+  "include/etl/generators/**",
+  "include/etl/private/*_cpp03.h",
+  "subprojects/**",
+  "test/UnitTest++/**",
+  "test/Deprecated/**",
+  "test/Performance/**",
+  "test/temp/**"
+]
+
+[formatter.cpp]
+command = "scripts/clang-format-wrapper"
+options = [ "-i", "--style=file" ]
+includes = [ "*.c", "*.cc", "*.cpp", "*.h", "*.hh", "*.hpp" ]

BUILD.bazel

@@ -0,0 +1,9 @@
+load("@rules_cc//cc:defs.bzl", "cc_library")
+
+package(default_visibility = ["//visibility:public"])
+
+cc_library(
+    name = "etl",
+    hdrs = glob(["include/**/*.h"]),
+    includes = ["include"],
+)

CONTRIBUTING.md

@@ -1,13 +1,17 @@
 # How to contribute
 
-If your are considering creating a pull request, please observe the following:
+Thanks for considering a contribution! Here’s what you need to know before opening a pull request:
 
 - If you are adding or modifying a feature, add *new* unit tests that test that feature.
 - If you are fixing a bug, add a unit test that *fails* before the bug fix is implemented.
-- Do not initiate a pull request until all of the units tests pass.
-- Branches should be based on the branch `master`.
+- Do not initiate a pull request until all of the units tests pass. See below for information on project files and test scripts.
+- Branches should be based on the branch `master`. If `development` has pending updates, I’ll rebase the PR against it before pulling..
+- For formatting help, you can use clang-format, or the convenience wrapper treefmt. See also [docs/source-formatting.md](docs/source-formatting.md)
 
-There is a project file for VS2022 for C++14, 17, 20, and bash scripts that run the tests for C++11, 14, 17, 20 under Linux with GCC and Clang.
+There is a project file for VS2022 for C++14, 17, 20, 23, and bash scripts that run the tests for C++11, 14, 17, 20, 23 under Linux with GCC and Clang.
+There are syntax-only check bash scripts that cover C++03, 11, 14, 17, 20, 23 under Linux with GCC and Clang.
 
 If you are thinking of adding a new feature then raise this on the GitHub Issues page for discussion as the maintainers and user of the ETL may have questions or suggestions.
-It is possible that the maintainer of the ETL or another contributor is already working on the same or a related feature.
+It is possible that the maintainer of the ETL or another contributor is already working on the same or a related feature. 
+  
+Take a look through our current issues and see if anything sparks your interest!

MODULE.bazel

@@ -0,0 +1,7 @@
+module(
+    name = "etl",
+    version = "0.0.0",
+)
+
+bazel_dep(name = "platforms", version = "0.0.11")
+bazel_dep(name = "rules_cc", version = "0.1.1")

MODULE.bazel.lock

@@ -0,0 +1,205 @@
+{
+  "lockFileVersion": 24,
+  "registryFileHashes": {
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+    "https://bcr.bazel.build/modules/abseil-cpp/20210324.2/MODULE.bazel": "7cd0312e064fde87c8d1cd79ba06c876bd23630c83466e9500321be55c96ace2",
+    "https://bcr.bazel.build/modules/abseil-cpp/20211102.0/MODULE.bazel": "70390338f7a5106231d20620712f7cccb659cd0e9d073d1991c038eb9fc57589",
+    "https://bcr.bazel.build/modules/abseil-cpp/20230125.1/MODULE.bazel": "89047429cb0207707b2dface14ba7f8df85273d484c2572755be4bab7ce9c3a0",
+    "https://bcr.bazel.build/modules/abseil-cpp/20230802.0.bcr.1/MODULE.bazel": "1c8cec495288dccd14fdae6e3f95f772c1c91857047a098fad772034264cc8cb",
+    "https://bcr.bazel.build/modules/abseil-cpp/20230802.0/MODULE.bazel": "d253ae36a8bd9ee3c5955384096ccb6baf16a1b1e93e858370da0a3b94f77c16",
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+    "https://bcr.bazel.build/modules/stardoc/0.7.1/source.json": "b6500ffcd7b48cd72c29bb67bcac781e12701cc0d6d55d266a652583cfcdab01",
+    "https://bcr.bazel.build/modules/upb/0.0.0-20220923-a547704/MODULE.bazel": "7298990c00040a0e2f121f6c32544bab27d4452f80d9ce51349b1a28f3005c43",
+    "https://bcr.bazel.build/modules/zlib/1.2.11/MODULE.bazel": "07b389abc85fdbca459b69e2ec656ae5622873af3f845e1c9d80fe179f3effa0",
+    "https://bcr.bazel.build/modules/zlib/1.3.1.bcr.5/MODULE.bazel": "eec517b5bbe5492629466e11dae908d043364302283de25581e3eb944326c4ca",
+    "https://bcr.bazel.build/modules/zlib/1.3.1.bcr.5/source.json": "22bc55c47af97246cfc093d0acf683a7869377de362b5d1c552c2c2e16b7a806",
+    "https://bcr.bazel.build/modules/zlib/1.3.1/MODULE.bazel": "751c9940dcfe869f5f7274e1295422a34623555916eb98c174c1e945594bf198"
+  },
+  "selectedYankedVersions": {},
+  "moduleExtensions": {
+    "@@rules_kotlin+//src/main/starlark/core/repositories:bzlmod_setup.bzl%rules_kotlin_extensions": {
+      "general": {
+        "bzlTransitiveDigest": "rL/34P1aFDq2GqVC2zCFgQ8nTuOC6ziogocpvG50Qz8=",
+        "usagesDigest": "QI2z8ZUR+mqtbwsf2fLqYdJAkPOHdOV+tF2yVAUgRzw=",
+        "recordedFileInputs": {},
+        "recordedDirentsInputs": {},
+        "envVariables": {},
+        "generatedRepoSpecs": {
+          "com_github_jetbrains_kotlin_git": {
+            "repoRuleId": "@@rules_kotlin+//src/main/starlark/core/repositories:compiler.bzl%kotlin_compiler_git_repository",
+            "attributes": {
+              "urls": [
+                "https://github.com/JetBrains/kotlin/releases/download/v1.9.23/kotlin-compiler-1.9.23.zip"
+              ],
+              "sha256": "93137d3aab9afa9b27cb06a824c2324195c6b6f6179d8a8653f440f5bd58be88"
+            }
+          },
+          "com_github_jetbrains_kotlin": {
+            "repoRuleId": "@@rules_kotlin+//src/main/starlark/core/repositories:compiler.bzl%kotlin_capabilities_repository",
+            "attributes": {
+              "git_repository_name": "com_github_jetbrains_kotlin_git",
+              "compiler_version": "1.9.23"
+            }
+          },
+          "com_github_google_ksp": {
+            "repoRuleId": "@@rules_kotlin+//src/main/starlark/core/repositories:ksp.bzl%ksp_compiler_plugin_repository",
+            "attributes": {
+              "urls": [
+                "https://github.com/google/ksp/releases/download/1.9.23-1.0.20/artifacts.zip"
+              ],
+              "sha256": "ee0618755913ef7fd6511288a232e8fad24838b9af6ea73972a76e81053c8c2d",
+              "strip_version": "1.9.23-1.0.20"
+            }
+          },
+          "com_github_pinterest_ktlint": {
+            "repoRuleId": "@@bazel_tools//tools/build_defs/repo:http.bzl%http_file",
+            "attributes": {
+              "sha256": "01b2e0ef893383a50dbeb13970fe7fa3be36ca3e83259e01649945b09d736985",
+              "urls": [
+                "https://github.com/pinterest/ktlint/releases/download/1.3.0/ktlint"
+              ],
+              "executable": true
+            }
+          },
+          "rules_android": {
+            "repoRuleId": "@@bazel_tools//tools/build_defs/repo:http.bzl%http_archive",
+            "attributes": {
+              "sha256": "cd06d15dd8bb59926e4d65f9003bfc20f9da4b2519985c27e190cddc8b7a7806",
+              "strip_prefix": "rules_android-0.1.1",
+              "urls": [
+                "https://github.com/bazelbuild/rules_android/archive/v0.1.1.zip"
+              ]
+            }
+          }
+        },
+        "recordedRepoMappingEntries": [
+          [
+            "rules_kotlin+",
+            "bazel_tools",
+            "bazel_tools"
+          ]
+        ]
+      }
+    }
+  },
+  "facts": {}
+}

README.md

@@ -1,22 +1,21 @@
-Embedded Template Library (ETL)
--------------------------
+# ![alt text](https://github.com/ETLCPP/etl/blob/master/images/etl64.png?raw=true) Embedded Template Library (ETL)
 
 ![GitHub release (latest by date)](https://img.shields.io/github/v/release/jwellbelove/etl)
 [![Release date](https://img.shields.io/github/release-date/jwellbelove/etl?color=%231182c3)](https://img.shields.io/github/release-date/jwellbelove/etl?color=%231182c3)
-[![Standard](https://img.shields.io/badge/c%2B%2B-98/03/11/14/17/20/23-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization)
+[![Standard](https://img.shields.io/badge/c%2B%2B-98/03/11/14/17/20/23/26-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization)
 [![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://opensource.org/licenses/MIT)
 ![GitHub contributors](https://img.shields.io/github/contributors-anon/ETLCPP/etl)
 ![GitHub forks](https://img.shields.io/github/forks/ETLCPP/etl?style=flat)
 ![GitHub Repo stars](https://img.shields.io/github/stars/ETLCPP/etl?style=flat)
 
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/msvc.yml/badge.svg?branch=master)
-[![Build status](https://ci.appveyor.com/api/projects/status/b7jgecv7unqjw4u0/branch/master?svg=true)](https://ci.appveyor.com/project/jwellbelove/etl/branch/master)
 
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-c++11.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-c++14.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-c++17.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-c++20.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-c++23.yml/badge.svg?branch=master)
+![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-c++26.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-syntax-checks.yml/badge.svg?branch=master)
 
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-c++11.yml/badge.svg?branch=master)
@@ -24,6 +23,7 @@ Embedded Template Library (ETL)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-c++17.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-c++20.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-c++23.yml/badge.svg?branch=master)
+![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-c++26.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-syntax-checks.yml/badge.svg?branch=master)
 
 [![Codacy Badge](https://api.codacy.com/project/badge/Grade/3c14cd918ccf40008d0bcd7b083d5946)](https://www.codacy.com/manual/jwellbelove/etl?utm_source=github.com&utm_medium=referral&utm_content=ETLCPP/etl&utm_campaign=Badge_Grade)
@@ -50,8 +50,8 @@ Its design goals include:
 
 -	Offering APIs that closely resemble those of the STL, enabling familiar and consistent usage.
 
--	Maintaining compatibility with C++98 while implementing many features introduced in later standards 
-(C++11/14/17/20/23) where possible.
+-	Maintaining compatibility with C++98 while implementing many features introduced in later standards
+(C++11/14/17/20/23/26) where possible.
 
 -	Ensuring deterministic behavior, which is critical in real-time and resource-constrained environments.
 
@@ -184,6 +184,84 @@ add_executable(foo main.cpp)
 target_link_libraries(foo PRIVATE etl::etl)
 ```
 
+## Profile definition
+
+When using ETL in a project, there is typically an `etl_profile.h` defined to
+adjust ETL to the project needs. ETL will automatically find `etl_profile.h`
+if it is available in the include path(s). If it's not available, ETL will
+work with default values.
+
+### Example
+
+```
+#ifndef __ETL_PROFILE_H__
+#define __ETL_PROFILE_H__
+
+#define ETL_TARGET_DEVICE_GENERIC
+#define ETL_TARGET_OS_NONE
+
+#define ETL_NO_STL
+
+#endif
+```
+
+## Platform specific implementation
+
+Although ETL is generally a self-contained header-only library, some interfaces need to be
+implemented in every project or platform, at least if those interfaces are actually being
+used, due to project specifics:
+
+| ETL header | Platform specific API to be implemented | Needed when using                   |
+|------------|-----------------------------------------|-------------------------------------|
+| `chrono.h` | `etl_get_high_resolution_clock()`       | `etl::high_resolution_clock::now()` |
+|            | `etl_get_system_clock()`                | `etl::system_clock::now()`          |
+|            | `etl_get_steady_clock()`                | `etl::steady_clock::now()`          |
+| `print.h`  | `etl_putchar()`                         | `etl::print()`                      |
+|            |                                         | `etl::println()`                    |
+
+### Example
+
+```
+#include <etl/chrono.h>
+#include <etl/print.h>
+
+extern "C"
+{
+
+etl::chrono::high_resolution_clock::rep etl_get_high_resolution_clock()
+{
+  return etl::chrono::high_resolution_clock::rep(static_cast<int64_t>(getSystemTimeNs()));
+}
+
+etl::chrono::system_clock::rep etl_get_system_clock()
+{
+  return etl::chrono::system_clock::rep(static_cast<int64_t>(getSystemTimeNs()));
+}
+
+etl::chrono::system_clock::rep etl_get_steady_clock()
+{
+  return etl::chrono::system_clock::rep(static_cast<int64_t>(getSystemTimeNs()));
+}
+
+void etl_putchar(int c)
+{
+  putByteToStdout(static_cast<uint8_t>(c));
+}
+
+}
+```
+
+The following default values apply if the respective macros are not defined
+(e.g. in `etl_profile.h`):
+
+| Macro                                         | Default                    |
+|-----------------------------------------------|----------------------------|
+| `ETL_CHRONO_SYSTEM_CLOCK_DURATION`            | `etl::chrono::nanoseconds` |
+| `ETL_CHRONO_SYSTEM_CLOCK_IS_STEADY`           | `true`                     |
+| `ETL_CHRONO_HIGH_RESOLUTION_CLOCK_DURATION`   | `etl::chrono::nanoseconds` |
+| `ETL_CHRONO_HIGH_RESOLUTION_CLOCK_IS_STEADY`  | `true`                     |
+| `ETL_CHRONO_STEADY_CLOCK_DURATION`            | `etl::chrono::nanoseconds` |
+
 ## Arduino library
 
 The content of this repo is available as a library in the Arduino IDE (search for the "Embedded Template Library" in the IDE library manager). The Arduino library repository is available at ```https://github.com/ETLCPP/etl-arduino```, see there for more details.

arduino/Embedded_Template_Library.h

@@ -2,79 +2,95 @@
 #ifndef ETL_EMBEDDED_TEMPLATE_LIBRARY_INCLUDED
 #define ETL_EMBEDDED_TEMPLATE_LIBRARY_INCLUDED
 
-#if defined(TEENSYDUINO) 
+#if defined(TEENSYDUINO)
 
-    #if defined(__AVR_ATmega32U4__)
-        #define ARDUINO_BOARD "Teensy 2.0"
-    #elif defined(__AVR_AT90USB1286__)       
-        #define ARDUINO_BOARD "Teensy++ 2.0"
-    #elif defined(__MK20DX128__)       
-        #define ARDUINO_BOARD "Teensy 3.0"
-    #elif defined(__MK20DX256__)       
-        #define ARDUINO_BOARD "Teensy 3.2" // and Teensy 3.1
-    #elif defined(__MKL26Z64__)       
-        #define ARDUINO_BOARD "Teensy LC"
-    #elif defined(__MK64FX512__)
-        #define ARDUINO_BOARD "Teensy 3.5"
-    #elif defined(__MK66FX1M0__)
-        #define ARDUINO_BOARD "Teensy 3.6"
-    #else
-       #define ARDUINO_BOARD "Unknown"
-    #endif
+  #if defined(__AVR_ATmega32U4__)
+    #define ARDUINO_BOARD "Teensy 2.0"
+  #elif defined(__AVR_AT90USB1286__)
+    #define ARDUINO_BOARD "Teensy++ 2.0"
+  #elif defined(__MK20DX128__)
+    #define ARDUINO_BOARD "Teensy 3.0"
+  #elif defined(__MK20DX256__)
+    #define ARDUINO_BOARD "Teensy 3.2" // and Teensy 3.1
+  #elif defined(__MKL26Z64__)
+    #define ARDUINO_BOARD "Teensy LC"
+  #elif defined(__MK64FX512__)
+    #define ARDUINO_BOARD "Teensy 3.5"
+  #elif defined(__MK66FX1M0__)
+    #define ARDUINO_BOARD "Teensy 3.6"
+  #elif defined(ARDUINO_TEENSY40)
+    #define ARDUINO_BOARD "Teensy 4.0"
+  #elif defined(ARDUINO_TEENSY41)
+    #define ARDUINO_BOARD "Teensy 4.1"
+  #elif defined(ARDUINO_TEENSY_MICROMOD)
+    #define ARDUINO_BOARD "Teensy MicroMod"
+  #else
+    #define ARDUINO_BOARD "Unknown"
+  #endif
+
+#elif defined(CORE_ARDUINO_PICO)
+
+  #if defined(PICO_RP2040)
+    #define ARDUINO_BOARD "RP2040"
+  #elif defined(PICO_RP2350)
+    #define ARDUINO_BOARD "RP2350"
+  #else
+    #define ARDUINO_BOARD "Unknown"
+  #endif
 
 #else // --------------- Arduino ------------------
 
-    #if defined(ARDUINO_AVR_ADK)       
-        #define ARDUINO_BOARD "Mega Adk"
-    #elif defined(ARDUINO_AVR_BT)
-        #define ARDUINO_BOARD "Bt"
-    #elif defined(ARDUINO_AVR_DUEMILANOVE)       
-        #define ARDUINO_BOARD "Duemilanove"
-    #elif defined(ARDUINO_AVR_ESPLORA)       
-        #define ARDUINO_BOARD "Esplora"
-    #elif defined(ARDUINO_AVR_ETHERNET)       
-        #define ARDUINO_BOARD "Ethernet"
-    #elif defined(ARDUINO_AVR_FIO)       
-        #define ARDUINO_BOARD "Fio"
-    #elif defined(ARDUINO_AVR_GEMMA)
-        #define ARDUINO_BOARD "Gemma"
-    #elif defined(ARDUINO_AVR_LEONARDO)       
-        #define ARDUINO_BOARD "Leonardo"
-    #elif defined(ARDUINO_AVR_LILYPAD)
-        #define ARDUINO_BOARD "Lilypad"
-    #elif defined(ARDUINO_AVR_LILYPAD_USB)
-        #define ARDUINO_BOARD "Lilypad Usb"
-    #elif defined(ARDUINO_AVR_MEGA)       
-        #define ARDUINO_BOARD "Mega"
-    #elif defined(ARDUINO_AVR_MEGA2560)       
-        #define ARDUINO_BOARD "Mega 2560"
-    #elif defined(ARDUINO_AVR_MICRO)       
-        #define ARDUINO_BOARD "Micro"
-    #elif defined(ARDUINO_AVR_MINI)       
-        #define ARDUINO_BOARD "Mini"
-    #elif defined(ARDUINO_AVR_NANO)       
-        #define ARDUINO_BOARD "Nano"
-    #elif defined(ARDUINO_AVR_NG)       
-        #define ARDUINO_BOARD "NG"
-    #elif defined(ARDUINO_AVR_PRO)       
-        #define ARDUINO_BOARD "Pro"
-    #elif defined(ARDUINO_AVR_ROBOT_CONTROL)       
-        #define ARDUINO_BOARD "Robot Ctrl"
-    #elif defined(ARDUINO_AVR_ROBOT_MOTOR)       
-        #define ARDUINO_BOARD "Robot Motor"
-    #elif defined(ARDUINO_AVR_UNO)       
-        #define ARDUINO_BOARD "Uno"
-    #elif defined(ARDUINO_AVR_YUN)       
-        #define ARDUINO_BOARD "Yun"
-    #elif defined(ARDUINO_SAM_DUE)       
-        #define ARDUINO_BOARD "Due"
-    #elif defined(ARDUINO_SAMD_ZERO)
-        #define ARDUINO_BOARD "Zero"
-    #elif defined(ARDUINO_ARC32_TOOLS)       
-        #define ARDUINO_BOARD "101"
-    #else
-       #define ARDUINO_BOARD "Unknown"
-    #endif
+  #if defined(ARDUINO_AVR_ADK)
+    #define ARDUINO_BOARD "Mega Adk"
+  #elif defined(ARDUINO_AVR_BT)
+    #define ARDUINO_BOARD "Bt"
+  #elif defined(ARDUINO_AVR_DUEMILANOVE)
+    #define ARDUINO_BOARD "Duemilanove"
+  #elif defined(ARDUINO_AVR_ESPLORA)
+    #define ARDUINO_BOARD "Esplora"
+  #elif defined(ARDUINO_AVR_ETHERNET)
+    #define ARDUINO_BOARD "Ethernet"
+  #elif defined(ARDUINO_AVR_FIO)
+    #define ARDUINO_BOARD "Fio"
+  #elif defined(ARDUINO_AVR_GEMMA)
+    #define ARDUINO_BOARD "Gemma"
+  #elif defined(ARDUINO_AVR_LEONARDO)
+    #define ARDUINO_BOARD "Leonardo"
+  #elif defined(ARDUINO_AVR_LILYPAD)
+    #define ARDUINO_BOARD "Lilypad"
+  #elif defined(ARDUINO_AVR_LILYPAD_USB)
+    #define ARDUINO_BOARD "Lilypad Usb"
+  #elif defined(ARDUINO_AVR_MEGA)
+    #define ARDUINO_BOARD "Mega"
+  #elif defined(ARDUINO_AVR_MEGA2560)
+    #define ARDUINO_BOARD "Mega 2560"
+  #elif defined(ARDUINO_AVR_MICRO)
+    #define ARDUINO_BOARD "Micro"
+  #elif defined(ARDUINO_AVR_MINI)
+    #define ARDUINO_BOARD "Mini"
+  #elif defined(ARDUINO_AVR_NANO)
+    #define ARDUINO_BOARD "Nano"
+  #elif defined(ARDUINO_AVR_NG)
+    #define ARDUINO_BOARD "NG"
+  #elif defined(ARDUINO_AVR_PRO)
+    #define ARDUINO_BOARD "Pro"
+  #elif defined(ARDUINO_AVR_ROBOT_CONTROL)
+    #define ARDUINO_BOARD "Robot Ctrl"
+  #elif defined(ARDUINO_AVR_ROBOT_MOTOR)
+    #define ARDUINO_BOARD "Robot Motor"
+  #elif defined(ARDUINO_AVR_UNO)
+    #define ARDUINO_BOARD "Uno"
+  #elif defined(ARDUINO_AVR_YUN)
+    #define ARDUINO_BOARD "Yun"
+  #elif defined(ARDUINO_SAM_DUE)
+    #define ARDUINO_BOARD "Due"
+  #elif defined(ARDUINO_SAMD_ZERO)
+    #define ARDUINO_BOARD "Zero"
+  #elif defined(ARDUINO_ARC32_TOOLS)
+    #define ARDUINO_BOARD "101"
+  #else
+    #define ARDUINO_BOARD "Unknown"
+  #endif
 #endif
 
 #endif

arduino/library-arduino.json

@@ -1,6 +1,6 @@
 {
   "name": "Embedded Template Library ETL",
-  "version": "20.44.1",
+  "version": "20.47.1",
   "authors": {
     "name": "John Wellbelove",
     "email": "john.wellbelove@etlcpp.com"

arduino/library-arduino.properties

@@ -1,5 +1,5 @@
 name=Embedded Template Library ETL
-version=20.44.1
+version=20.47.1
 author= John Wellbelove <john.wellbelove@etlcpp.com>
 maintainer=John Wellbelove <john.wellbelove@etlcpp.com>
 license=MIT

docs/_config.yml

@@ -0,0 +1,6 @@
+plugins:
+  - jekyll-relative-links
+relative_links:
+  enabled: true
+include:
+  - manchester.md

docs/bazel.md

@@ -0,0 +1,295 @@
+# Building ETL with Bazel
+
+ETL provides first-class [Bazel](https://bazel.build/) support, both for developing ETL itself and for consuming it as a dependency in your own projects.
+
+## Prerequisites
+
+- [Bazelisk](https://github.com/bazelbuild/bazelisk) (recommended) or [Bazel](https://bazel.build/install) 7.0 or later (with Bzlmod support)
+
+[Bazelisk](https://github.com/bazelbuild/bazelisk) is a launcher that automatically downloads and runs the Bazel version specified in the `.bazelversion` file at the project root. This ensures all contributors use a consistent Bazel version. Simply install Bazelisk and use `bazel` as usual — it transparently delegates to the correct version.
+
+## Syntax Checks
+
+To validate that every ETL header is well-formed and compiles on its own (equivalent to `test/run-syntax-checks.sh` for CMake):
+
+```sh
+bazel build //test/syntax_check:syntax_check
+```
+
+This compiles a set of minimal `.t.cpp` files, each of which includes a single ETL header, with strict warning flags enabled.
+
+## Cleaning Build Artifacts
+
+To remove all build outputs and symlinks (`bazel-bin`, `bazel-out`, `bazel-etl`, etc.):
+
+```sh
+bazel clean
+```
+
+For a full cleanup including the external dependency cache:
+
+```sh
+bazel clean --expunge
+```
+
+## Running Unit Tests
+
+To run the full test suite:
+
+```sh
+bazel test //test:etl_tests
+```
+
+You can also pass standard Bazel flags:
+
+```sh
+# Run with verbose test output
+bazel test //test:etl_tests --test_output=all
+
+# Run tests matching a filter (UnitTest++ subset)
+bazel test //test:etl_tests --test_arg=<suite_name>
+```
+
+## Using ETL in Your Project
+
+### With Bzlmod (recommended, Bazel 7+)
+
+Add ETL as a dependency in your project's `MODULE.bazel`:
+
+```python
+bazel_dep(name = "etl", version = "20.47.1")
+
+git_override(
+    module_name = "etl",
+    remote = "https://github.com/ETLCPP/etl.git",
+    tag = "20.47.1",  # or a specific commit
+)
+```
+
+Then depend on it in your `BUILD.bazel`:
+
+```python
+cc_library(
+    name = "my_library",
+    srcs = ["my_library.cpp"],
+    hdrs = ["my_library.h"],
+    deps = ["@etl//:etl"],
+)
+```
+
+### With WORKSPACE (legacy)
+
+In your `WORKSPACE` file:
+
+```python
+load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
+
+git_repository(
+    name = "etl",
+    remote = "https://github.com/ETLCPP/etl.git",
+    tag = "20.47.1",
+)
+```
+
+Then use `deps = ["@etl//:etl"]` in your targets as shown above.
+
+## Project Structure
+
+| File | Purpose |
+|---|---|
+| `MODULE.bazel` | Module definition and dependencies |
+| `BUILD.bazel` | Exposes ETL as a `cc_library` |
+| `.bazelversion` | Bazel version for Bazelisk |
+| `.bazelrc` | Default Bazel settings |
+| `test/BUILD.bazel` | Unit test target |
+| `test/syntax_check/BUILD.bazel` | Header syntax check target |
+| `test/UnitTest++/BUILD.bazel` | Vendored UnitTest++ framework |
+
+## Cross-Compilation
+
+Bazel supports cross-compilation through its [platforms](https://bazel.build/extending/platforms) and [toolchains](https://bazel.build/extending/toolchains) system. Since ETL is a header-only library, there is nothing to cross-compile for the library itself. However, when building tests or consuming ETL in an application targeting a different architecture, you need to define a platform and register an appropriate C++ toolchain.
+
+Example platform definition (e.g. in a `platforms/BUILD.bazel`):
+
+```python
+platform(
+    name = "linux_arm64",
+    constraint_values = [
+        "@platforms//os:linux",
+        "@platforms//cpu:aarch64",
+    ],
+)
+```
+
+Then build with:
+
+```sh
+bazel build //:etl --platforms=//platforms:linux_arm64
+```
+
+> **Note:** You must also have a C++ toolchain registered that supports the target platform.
+> See the [Bazel toolchains documentation](https://bazel.build/extending/toolchains) for details.
+
+### Running Cross-Compiled Tests under QEMU
+
+Cross-compiled test binaries cannot run natively on the host. Pre-defined configurations in `.bazelrc` select the correct cross-compiler via `--repo_env=CC`, set the build flags to match `.devcontainer/run-tests.sh` (C++23, No-STL, `-O0`), and use `--run_under` to execute the resulting binary under the appropriate QEMU emulator:
+
+```sh
+# Cross-build and run tests for ARM (armhf)
+bazel test //test:etl_tests --config=armhf
+
+# Other architectures
+bazel test //test:etl_tests --config=i386
+bazel test //test:etl_tests --config=powerpc
+bazel test //test:etl_tests --config=riscv64
+bazel test //test:etl_tests --config=s390x
+```
+
+These configs are designed to run inside the Docker containers under `.devcontainer/`, which provide the cross-compiler toolchains and QEMU binaries. Each config sets `CC`, `AR`, `LD`, `NM`, `STRIP`, and `OBJDUMP` via `--repo_env` so that Bazel's auto-configured toolchain finds the complete prefixed cross-tool suite.
+
+You can also use `--run_under` directly for custom setups:
+
+```sh
+bazel test //test:etl_tests --run_under=/usr/bin/qemu-arm-static
+```
+
+## Compiler and Build Configuration
+
+Unlike CMake where options like `ETL_CXX_STANDARD` and `CMAKE_CXX_COMPILER` are set at configure time, Bazel uses command-line flags and `.bazelrc` configurations.
+
+### C++ Standard Version
+
+Use `--cxxopt` to pass the desired standard flag:
+
+```sh
+# C++17 (default in .bazelrc)
+bazel test //test:etl_tests --cxxopt=-std=c++17
+
+# C++20
+bazel test //test:etl_tests --cxxopt=-std=c++20
+
+# C++23
+bazel test //test:etl_tests --cxxopt=-std=c++23
+
+# C++14
+bazel test //test:etl_tests --cxxopt=-std=c++14
+```
+
+### Optimization Level
+
+Use `--compilation_mode` (shorthand `-c`) for standard profiles, or `--copt` for explicit flags:
+
+```sh
+# Debug (default) — no optimization, debug symbols
+bazel test //test:etl_tests -c dbg
+
+# Optimized — O2 with NDEBUG
+bazel test //test:etl_tests -c opt
+
+# Fast build — no optimization, no debug symbols
+bazel test //test:etl_tests -c fastbuild
+
+# Custom optimization level
+bazel test //test:etl_tests --copt=-O3
+bazel test //test:etl_tests --copt=-O1
+bazel test //test:etl_tests --copt=-Os
+```
+
+### Selecting the Compiler (GCC vs Clang)
+
+Bazel uses the system's default `CC` environment variable. Override it to switch compilers:
+
+```sh
+# Use Clang
+bazel test //test:etl_tests --repo_env=CC=clang
+
+# Use a specific GCC version
+bazel test //test:etl_tests --repo_env=CC=gcc-13
+
+# Use a specific Clang version
+bazel test //test:etl_tests --repo_env=CC=clang-18
+```
+
+> **Note:** Bazel's auto-configured toolchain infers the C++ compiler from `CC` automatically
+> (e.g. `CC=gcc-13` → `g++-13` for C++ compilation). There is no need to set `CXX` separately.
+
+### Combining Options
+
+Flags can be combined freely:
+
+```sh
+# Clang, C++20, optimized
+bazel test //test:etl_tests --repo_env=CC=clang --cxxopt=-std=c++20 -c opt
+
+# GCC 13, C++23, debug
+bazel test //test:etl_tests --repo_env=CC=gcc-13 --cxxopt=-std=c++23 -c dbg
+```
+
+### STL vs. No-STL Mode
+
+ETL can operate without the standard library, which is common on bare-metal embedded targets. Use `--copt` to define `ETL_NO_STL`:
+
+```sh
+# Build and test without STL
+bazel test //test:etl_tests --copt=-DETL_NO_STL
+
+# Build with STL (default, no flag needed)
+bazel test //test:etl_tests
+```
+
+When `ETL_NO_STL` is defined, ETL provides its own implementations of containers, algorithms, and utilities instead of delegating to `<algorithm>`, `<type_traits>`, etc.
+
+### Type Traits Configuration
+
+ETL supports three type traits strategies, controlled via preprocessor defines:
+
+| Mode | Define | Description |
+|---|---|---|
+| **STL type traits** | *(default)* | Uses `<type_traits>` from the standard library |
+| **Compiler builtins** | `ETL_USE_TYPE_TRAITS_BUILTINS` | Uses compiler intrinsics (`__is_trivially_copyable`, etc.) — useful when STL headers are unavailable or incomplete |
+| **User-defined** | `ETL_USER_DEFINED_TYPE_TRAITS` | Uses ETL's own type traits implementations |
+
+```sh
+# Use compiler built-in type traits
+bazel test //test:etl_tests --copt=-DETL_USE_TYPE_TRAITS_BUILTINS
+
+# Use ETL's own user-defined type traits
+bazel test //test:etl_tests --copt=-DETL_USER_DEFINED_TYPE_TRAITS
+```
+
+These are mutually exclusive — define at most one. If neither is defined and STL is available, ETL uses `<type_traits>`.
+
+### Other Configuration Defines
+
+Additional defines can be passed the same way via `--copt=-D...`:
+
+| Define | Description |
+|---|---|
+| `ETL_FORCE_TEST_CPP03_IMPLEMENTATION` | Force C++03 code paths even when a newer standard is available |
+| `ETL_MESSAGES_ARE_NOT_VIRTUAL` | Use non-virtual message types |
+
+```sh
+# Force C++03 implementation paths
+bazel test //test:etl_tests --copt=-DETL_FORCE_TEST_CPP03_IMPLEMENTATION
+```
+
+### Using `.bazelrc` Presets
+
+To avoid retyping flags, add configurations to `.bazelrc`:
+
+```
+# .bazelrc
+
+# Named configurations
+build:clang    --repo_env=CC=clang
+build:gcc13    --repo_env=CC=gcc-13
+build:c++20    --cxxopt=-std=c++20
+build:c++23    --cxxopt=-std=c++23
+build:release  --compilation_mode=opt
+```
+
+Then use them with `--config`:
+
+```sh
+bazel test //test:etl_tests --config=clang --config=c++20 --config=release
+```

docs/docker.md

@@ -0,0 +1,289 @@
+# Docker for Development
+
+## Overview
+
+The ETL repository ships a set of Docker-based development environments under
+`.devcontainer/`. They give every contributor an identical, reproducible toolchain
+regardless of host operating system. Three flavours are provided:
+
+| Flavour | Path | Purpose |
+|---|---|---|
+| **Default** | `.devcontainer/` | Day-to-day development (Microsoft C++ dev-container base image) |
+| **Compiler-specific** | `.devcontainer/gcc09/` … `.devcontainer/gcc15/`, `.devcontainer/clang7/` … `.devcontainer/clang21/` | Test against a specific GCC or Clang version |
+| **s390x big-endian** | `.devcontainer/s390x/` | Cross-compile and run tests on an s390x target via QEMU |
+
+All containers include CMake, Make, Git, Python 3, cogapp (the code generator used
+by ETL), clang-format 18, and treefmt.
+
+## Prerequisites
+
+- **Docker** (or Docker Desktop) – any recent version that supports `docker build`
+  and `docker run`.
+- **VS Code** with the
+  [Dev Containers](https://marketplace.visualstudio.com/items?itemName=ms-vscode-remote.remote-containers)
+  extension (optional, but recommended for the smoothest experience).
+- **Git** – to clone the repository.
+
+## Quick Start
+
+### Using the helper script
+
+The fastest way to get a shell inside the default container from the project root:
+
+```bash
+./scripts/run-docker.sh
+```
+
+This script performs two steps:
+
+1. **Builds** the image from `.devcontainer/Dockerfile` and tags it `etl`.
+2. **Runs** an interactive container that bind-mounts the repository at
+   `/home/vscode/etl` so that edits made inside the container are visible on
+   the host (and vice versa).
+
+You are dropped into a Bash shell as the `vscode` user with the working
+directory set to the repository root.
+
+### Using VS Code Dev Containers
+
+1. Open the repository folder in VS Code.
+2. When prompted, click **Reopen in Container** – or run the command
+   *Dev Containers: Reopen in Container* from the command palette.
+3. VS Code reads `.devcontainer/devcontainer.json`, builds the image, and
+   attaches to the running container automatically.
+
+To open a **specific compiler variant** instead, run
+*Dev Containers: Open Folder in Container…* and pick the sub-folder (e.g.
+`.devcontainer/gcc14/`), or use the command palette action
+*Dev Containers: Open Named Container Configuration…* and select the desired
+name (e.g. "Gcc 14", "Clang 18").
+
+## Default Development Container
+
+The file `.devcontainer/Dockerfile` is a multi-purpose image used by the
+default configuration **and** by every compiler-specific variant (they simply
+override the `BASE_IMAGE_NAME` build argument).
+
+### Base image
+
+```text
+mcr.microsoft.com/devcontainers/cpp:2
+```
+
+The exact digest is pinned in `devcontainer.json` so that builds are
+reproducible even if the upstream tag is updated.
+
+### Installed tools
+
+The Dockerfile installs the following on top of the base image:
+
+| Tool | Purpose |
+|---|---|
+| `python3`, `pip` | Runtime for helper scripts |
+| `python3-cogapp` / `cogapp` | ETL code generator |
+| `git` | Version control |
+| `wget` | Downloading additional tooling |
+| `cmake`, `make` | Build system |
+| `clang-format` (v18) | Source formatting (see [source-formatting.md](source-formatting.md)) |
+| `treefmt` (v2.4.1) | Single-command formatting wrapper |
+
+### Reproducible builds with Debian snapshots
+
+The default configuration sets the build argument
+`DEBIAN_SNAPSHOT=20260223T000000Z`. When this value is not `"none"`, the
+Dockerfile rewrites the APT sources to point at
+`snapshot.debian.org/archive/debian/<timestamp>`, ensuring that every
+contributor installs identical package versions. Compiler-specific variants
+that are based on upstream `gcc:*` or `silkeh/clang:*` images set
+`DEBIAN_SNAPSHOT=none` because those images manage their own package sources.
+
+## Compiler-Specific Containers
+
+Each sub-folder under `.devcontainer/` contains a `devcontainer.json` that
+reuses the **same** `Dockerfile` (`../Dockerfile`) but overrides the
+`BASE_IMAGE_NAME` build argument to select a different compiler.
+
+### GCC variants
+
+| Folder | Base image | Name |
+|---|---|---|
+| `gcc09/` | `gcc:9` | Gcc 09 |
+| `gcc10/` | `gcc:10` | Gcc 10 |
+| `gcc11/` | `gcc:11` | Gcc 11 |
+| `gcc12/` | `gcc:12` | Gcc 12 |
+| `gcc13/` | `gcc:13` | Gcc 13 |
+| `gcc14/` | `gcc:14` | Gcc 14 |
+| `gcc15/` | `gcc:15` | Gcc 15 |
+
+### Clang variants
+
+| Folder | Base image | Name |
+|---|---|---|
+| `clang7/` | `silkeh/clang:7` | Clang 7 |
+| `clang8/` | `silkeh/clang:8` | Clang 8 |
+| `clang9/` | `silkeh/clang:9` | Clang 9 |
+| `clang10/` | `silkeh/clang:10` | Clang 10 |
+| `clang11/` | `silkeh/clang:11` | Clang 11 |
+| `clang12/` | `silkeh/clang:12` | Clang 12 |
+| `clang13/` | `silkeh/clang:13` | Clang 13 |
+| `clang14/` | `silkeh/clang:14` | Clang 14 |
+| `clang15/` | `silkeh/clang:15` | Clang 15 |
+| `clang16/` | `silkeh/clang:16` | Clang 16 |
+| `clang17/` | `silkeh/clang:17` | Clang 17 |
+| `clang18/` | `silkeh/clang:18` | Clang 18 |
+| `clang19/` | `silkeh/clang:19` | Clang 19 |
+| `clang20/` | `silkeh/clang:20` | Clang 20 |
+| `clang21/` | `silkeh/clang:21` | Clang 21 |
+
+All compiler-specific variants set `DEBIAN_SNAPSHOT` to `"none"` because they
+rely on the upstream image's own package sources.
+
+## s390x Big-Endian Cross-Compilation
+
+The `s390x` container lives in `.devcontainer/s390x/` and has its **own**
+Dockerfile (it does not reuse the default one). It is based on
+`debian:trixie` and installs:
+
+- QEMU user-mode emulation (`qemu-user-static`, `qemu-user`, `binfmt-support`)
+- s390x cross-compilation toolchain (`gcc-s390x-linux-gnu`,
+  `g++-s390x-linux-gnu`)
+- CMake, Make, Ninja, Git, wget
+
+### Container setup
+
+Open `.devcontainer/s390x/` as a Dev Container in VS Code, or build manually:
+
+```bash
+docker build -t etl-s390x .devcontainer/s390x
+docker run -it --rm -v .:/workspaces/etl -w /workspaces/etl etl-s390x
+```
+
+### CMake toolchain
+
+A CMake toolchain file is provided at
+`.devcontainer/s390x/toolchain-s390x.cmake`. It sets:
+
+- `CMAKE_SYSTEM_PROCESSOR` to `s390x`
+- Cross-compilers `s390x-linux-gnu-gcc` / `g++`
+- `CMAKE_CROSSCOMPILING_EMULATOR` to `/usr/bin/qemu-s390x-static`
+
+The VS Code Dev Container configuration already passes this toolchain file
+via `cmake.configureArgs`, so CMake Tools picks it up automatically.
+
+### Running tests under QEMU
+
+Because the toolchain file sets `CMAKE_CROSSCOMPILING_EMULATOR`, CTest
+automatically invokes `qemu-s390x-static` when running test binaries.
+No extra flags are needed:
+
+```bash
+cmake -S test -B build-s390x \
+  -DCMAKE_TOOLCHAIN_FILE=.devcontainer/s390x/toolchain-s390x.cmake \
+  -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_CXX_STANDARD=17 -G Ninja
+cmake --build build-s390x
+ctest --test-dir build-s390x
+```
+
+## Building and Running Tests
+
+Once inside any container (default, compiler-specific, or s390x) you can
+build and run the ETL test suite.
+
+### Quick CMake workflow
+
+```bash
+# Configure – build tests with C++17
+cmake -S test -B build -DBUILD_TESTS=ON -DETL_CXX_STANDARD=17
+
+# Build
+cmake --build build -j $(nproc)
+
+# Run tests
+ctest --test-dir build
+```
+
+Change `DETL_CXX_STANDARD` to `11`, `14`, `17`, `20`, or `23` as needed.
+Add `-DNO_STL=ON` to build without the standard library.
+
+### Using the run-tests script
+
+The repository also provides a convenience script in `test/`:
+
+```bash
+cd test
+./run-tests.sh <standard> [optimisation] [threads] [sanitizer] [compiler] [verbose]
+```
+
+| Argument | Values | Default |
+|---|---|---|
+| C++ standard | `11`, `14`, `17`, `20`, `23` | *(required)* |
+| Optimisation | `0`, `1`, `2`, `3` | `0` |
+| Threads | any integer | `4` |
+| Sanitizer | `s` (enable) / `n` (disable) | `n` |
+| Compiler | `gcc` / `clang` | all |
+| Verbose | `v` (enable) / `n` (disable) | `n` |
+
+Example – run C++17 tests at `-O2` with 8 threads using GCC:
+
+```bash
+./run-tests.sh 17 2 8 n gcc n
+```
+
+## Formatting Inside the Container
+
+The default container ships with **clang-format 18** and **treefmt**.
+See [source-formatting.md](source-formatting.md) for the full formatting guide.
+
+Quick reference:
+
+```bash
+# Format all tracked C/C++ files with treefmt
+treefmt
+
+# Or use clang-format directly via the wrapper
+./scripts/clang-format-wrapper -i include/etl/*.h
+```
+
+The wrapper script `scripts/clang-format-wrapper` resolves the correct
+clang-format binary (prefers `clang-format-18`, falls back to `clang-format`
+after checking the major version).
+
+## Customisation
+
+To add extra packages or tools to the default container, edit
+`.devcontainer/Dockerfile`. The image follows a straightforward
+`apt-get install` pattern, so adding a new package is as simple as appending
+it to the existing `apt-get` line.
+
+To create a new compiler variant:
+
+1. Create a folder under `.devcontainer/` (e.g. `.devcontainer/gcc16/`).
+2. Add a `devcontainer.json` that references `"../Dockerfile"` and sets
+   `BASE_IMAGE_NAME` to the desired image (e.g. `gcc:16`).
+3. Set `DEBIAN_SNAPSHOT` to `"none"` for upstream compiler images.
+
+Example:
+
+```jsonc
+{
+  "name": "Gcc 16",
+  "build": {
+    "dockerfile": "../Dockerfile",
+    "args": {
+      "BASE_IMAGE_NAME": "gcc:16",
+      "DEBIAN_SNAPSHOT": "none"
+    },
+    "context": "../context"
+  }
+}
+```
+
+## Troubleshooting
+
+| Symptom | Cause / Fix |
+|---|---|
+| `apt-get` fails with *"Release file … is not valid yet"* | The Debian snapshot timestamp is in the future relative to the build host clock. Either update `DEBIAN_SNAPSHOT` in `devcontainer.json` or set it to `"none"`. |
+| `clang-format` reports the wrong version | The wrapper expects version **18**. Make sure the image installs `clang-format` (or `clang-format-18`) and that the binary is on `PATH`. |
+| Permission errors on mounted files | The `run-docker.sh` script runs as user `vscode`. Ensure your host UID matches, or adjust the `--user` flag. |
+| s390x tests crash immediately | Verify that `qemu-user-static` is installed and that `binfmt-support` is active. On some hosts you may need to register binfmt handlers with `docker run --privileged --rm tonistiigi/binfmt --install all`. |
+| Build is very slow the first time | Docker is downloading and building the image from scratch. Subsequent builds use the layer cache and are much faster. |

docs/format.md

@@ -0,0 +1,389 @@
+# ETL Format & Print
+
+## 1. Overview
+
+ETL provides text formatting facilities modelled on C++20 `std::format` and C++23
+`std::print`.  They allow type-safe, positional formatting of values into strings
+or directly to a character output device — without heap allocation.
+
+**Minimum language standard:** C++11 (`ETL_USING_CPP11`).
+
+**Headers:**
+
+| Header | Provides |
+|---|---|
+| `etl/format.h` | `etl::format_to`, `etl::format_to_n`, `etl::formatted_size` |
+| `etl/print.h`  | `etl::print`, `etl::println` (includes `etl/format.h`) |
+
+## 2. `etl::format_to`
+
+### Generic output-iterator overload
+
+```cpp
+template<typename OutputIt, class... Args>
+OutputIt format_to(OutputIt out, format_string<Args...> fmt, Args&&... args);
+```
+
+Formats `args` according to the format string `fmt` and writes the result through
+the output iterator `out`.  Returns an iterator past the last character written.
+
+`OutputIt` can be any output iterator whose dereferenced type is assignable from
+`char`, for example `etl::istring::iterator` or
+`etl::back_insert_iterator<etl::istring>`.
+
+```cpp
+etl::string<100> s;
+
+// Using a raw iterator — you must resize the string yourself
+etl::istring::iterator result = etl::format_to(s.begin(), "{0} {1}", 34, 56);
+s.uninitialized_resize(static_cast<size_t>(result - s.begin()));
+// s == "34 56"
+
+// Using a back_insert_iterator — string grows automatically
+s.clear();
+etl::back_insert_iterator<etl::istring> it(s);
+etl::format_to(it, "{} {}", 65, 34);
+// s == "65 34"
+```
+
+### `etl::istring&` overload (ETL-specific)
+
+```cpp
+template<class... Args>
+etl::istring::iterator format_to(etl::istring& out,
+                                  format_string<Args...> fmt,
+                                  Args&&... args);
+```
+
+Convenience overload that writes into an `etl::istring` (or any derived
+`etl::string<N>`).  The string is automatically resized to the number of
+characters written, up to `out.max_size()`.  Returns an iterator past the
+last character written.
+
+```cpp
+etl::string<100> s;
+etl::format_to(s, "Hello, {}!", "world");
+// s == "Hello, world!"
+```
+
+### `etl::format_to_n`
+
+```cpp
+template<typename OutputIt, class... Args>
+OutputIt format_to_n(OutputIt out, size_t n,
+                     format_string<Args...> fmt, Args&&... args);
+```
+
+Like `format_to`, but writes **at most** `n` characters.  Characters beyond the
+limit are silently discarded.
+
+```cpp
+etl::string<10> s = "abcdefghij";
+etl::format_to_n(s.begin(), 3, "xy{}", 123);
+// s == "xy1defghij"   (only 3 chars written)
+```
+
+## 3. `etl::formatted_size`
+
+```cpp
+template<class... Args>
+size_t formatted_size(format_string<Args...> fmt, Args&&... args);
+```
+
+Returns the total number of characters that `format_to` would produce, without
+actually writing anything.  Useful for pre-computing buffer sizes.
+
+```cpp
+size_t n;
+n = etl::formatted_size("");            // 0
+n = etl::formatted_size("{}", "");      // 0
+n = etl::formatted_size("xyz{}", 12);  // 5
+n = etl::formatted_size("{}", "abc");   // 3
+```
+
+## 4. `etl::print` and `etl::println`
+
+Declared in `etl/print.h`.
+
+### `etl::print`
+
+```cpp
+template<class... Args>
+void print(etl::format_string<Args...> fmt, Args&&... args);
+```
+
+Formats the arguments and outputs each character by calling `etl_putchar()`.
+
+### `etl::println`
+
+```cpp
+// With arguments — prints formatted text followed by '\n'
+template<class... Args>
+void println(etl::format_string<Args...> fmt, Args&&... args);
+
+// Without arguments — prints a bare newline
+void println();
+```
+
+### Implementing `etl_putchar`
+
+`etl/print.h` declares (but does not define) the following C-linkage function:
+
+```cpp
+extern "C" void etl_putchar(int c);
+```
+
+You **must** provide a definition in your project.  The `int` parameter follows
+the convention of the standard `putchar()` and carries a single `char` value.
+
+Typical implementations forward to a UART, a debug probe, `putchar`, or any
+other single-character output sink:
+
+```cpp
+// Example: forward to standard putchar
+extern "C" void etl_putchar(int c)
+{
+  putchar(c);
+}
+```
+
+### Example
+
+```cpp
+etl::print("x = {}, y = {}\n", 10, 20);   // "x = 10, y = 20\n"
+etl::println("Hello, {}!", "world");        // "Hello, world!\n"
+etl::println();                             // "\n"
+```
+
+## 5. Format String Syntax
+
+A format string is ordinary text with **replacement fields** delimited by braces:
+
+```
+"literal text {} more text {1:>10} end"
+```
+
+### Replacement field grammar
+
+```
+replacement_field ::= '{' [arg_id] [':' format_spec] '}'
+arg_id            ::= integer            // e.g. 0, 1, 2 …
+format_spec       ::= [[fill]align] [sign] ['#'] ['0'] [width] ['.' precision] ['L'] [type]
+```
+
+| Component | Syntax | Description |
+|---|---|---|
+| **Argument index** | `{0}`, `{1}`, … | Manual positional indexing. Cannot be mixed with automatic indexing. |
+| **Automatic index** | `{}` | Uses the next argument in order. Cannot be mixed with manual indexing. |
+| **Fill character** | any character except `{` or `}` | Used together with an alignment specifier. Default is space (` `). |
+| **Alignment** | `<` left, `>` right, `^` center | Aligns the formatted value within the given *width*. |
+| **Sign** | `+` always, `-` negative only (default), ` ` space for positive | Controls sign display for numeric types. |
+| **`#` (alt form)** | `#` | Adds `0x`/`0X` for hex, `0b`/`0B` for binary, `0` for octal. |
+| **`0` (zero-pad)** | `0` | Pads the number with leading zeros (after sign/prefix). |
+| **Width** | integer, or `{}` / `{n}` | Minimum field width.  Supports nested replacement fields for dynamic width. |
+| **Precision** | `.` integer, or `.{}` / `.{n}` | For strings: maximum characters to output.  For floats: number of decimal digits.  Supports nested replacement fields. |
+| **`L`** | `L` | Locale-specific flag (parsed but currently ignored). |
+| **Type** | see [Presentation Types](#7-presentation-types-per-argument-kind) | Selects the output representation. |
+
+### Examples
+
+```cpp
+etl::format_to(s, "{:>10}", 42);       // "        42"
+etl::format_to(s, "{:*^10}", 42);      // "****42****"
+etl::format_to(s, "{:+05d}", 67);      // "+00067"
+etl::format_to(s, "{:#x}", 0x3f4);     // "0x3f4"
+etl::format_to(s, "{:.3s}", "abcdef"); // "abc"
+etl::format_to(s, "{1} {0}", 1, 2);    // "2 1"
+```
+
+## 6. Supported Argument Types
+
+The core set of formattable types (matching `std::basic_format_arg`):
+
+| Category | Types |
+|---|---|
+| Boolean | `bool` |
+| Character | `char` |
+| Signed integer | `int`, `long long int` |
+| Unsigned integer | `unsigned int`, `unsigned long long int` |
+| Floating-point *(opt-in)* | `float`, `double`, `long double` — requires `ETL_USING_FORMAT_FLOATING_POINT` |
+| String | `const char*`, `etl::string_view` |
+| Pointer | `const void*` |
+
+### Implicit conversions
+
+Types not listed above are converted automatically before formatting:
+
+| Source type | Stored as |
+|---|---|
+| `short` | `int` |
+| `unsigned short`, `uint16_t` | `unsigned int` |
+| `long int` | `int` or `long long int` (platform-dependent) |
+| `unsigned long int`, `size_t` | `unsigned int` or `unsigned long long int` |
+| `int8_t` (`signed char`) | `char` |
+| `uint8_t` (`unsigned char`) | `char` |
+| `int16_t` | `int` |
+| `uint32_t` | `unsigned int` |
+| `int32_t` | `int` |
+| `etl::string<N>` | `etl::string_view` (lifetime of the temporary is guaranteed) |
+| any pointer `T*` | `const void*` |
+
+## 7. Presentation Types per Argument Kind
+
+### Integers (`int`, `unsigned int`, `long long int`, `unsigned long long int`)
+
+| Type | Meaning | Example |
+|---|---|---|
+| `d` *(default)* | Decimal | `134` → `"134"` |
+| `x` | Lowercase hexadecimal | `0x3f4` → `"3f4"` |
+| `X` | Uppercase hexadecimal | `0x3f4` → `"3F4"` |
+| `o` | Octal | `034` → `"34"` |
+| `b` | Lowercase binary | `0b1010` → `"1010"` |
+| `B` | Uppercase binary | `0b1010` → `"1010"` |
+| `c` | Character (value as char) | `67` → `"C"` |
+
+With `#`: prefixes `0x`/`0X`, `0b`/`0B`, or leading `0` for octal.
+
+### Characters (`char`, `signed char`, `unsigned char`)
+
+| Type | Meaning | Example |
+|---|---|---|
+| `c` *(default)* | Character itself | `'s'` → `"s"` |
+| `?` | Debug / escaped | `'\n'` → `"'\\n'"` |
+| `d` | Decimal code point | `'a'` → `"97"` |
+| `x` / `X` | Hex code point | `'a'` → `"61"` |
+
+### Booleans (`bool`)
+
+| Type | Meaning | Example |
+|---|---|---|
+| *(default)* | `false` / `true` | `true` → `"true"` |
+| `s` | Same as default | `true` → `"true"` |
+| `d` | `0` / `1` | `true` → `"1"` |
+| `x` / `X` | Hex `0` / `1` | `true` → `"1"` |
+| `o` | Octal (with `#`: `01`) | `true` → `"01"` |
+
+### Strings (`const char*`, `etl::string_view`, `etl::string<N>`)
+
+| Type | Meaning | Example |
+|---|---|---|
+| `s` *(default)* | String output | `"data1"` → `"data1"` |
+| `?` | Debug / escaped | `"data1\n"` → `"\"data1\\n\""` |
+
+Width and precision apply: width sets the minimum field width; precision (`.N`)
+truncates the string to at most *N* characters.
+
+```cpp
+etl::format_to(s, "{:>10s}", "data1");    // "     data1"
+etl::format_to(s, "{:.3s}", "abcdef");    // "abc"
+etl::format_to(s, ".{:^8.3s}!", "data1"); // ".  dat   !"
+```
+
+### Pointers (`const void*`)
+
+| Type | Meaning | Example |
+|---|---|---|
+| `p` *(default)* | Lowercase hex with `0x` prefix | `nullptr` → `"0x0"` |
+| `P` | Uppercase hex with `0X` prefix | `nullptr` → `"0X0"` |
+
+### Floating-point (`float`, `double`, `long double`)
+
+Requires `ETL_USING_FORMAT_FLOATING_POINT`.
+
+| Type | Meaning | Example |
+|---|---|---|
+| *(default)* | Shortest representation | `1.5f` → `"1.5"` |
+| `e` / `E` | Scientific notation | `1.0f` → `"1.000000e+00"` |
+| `f` / `F` | Fixed-point notation | `1.125f` → `"1.125000"` |
+| `g` / `G` | General (fixed or scientific) | `1e10f` → `"1.000000e+10"` |
+| `a` / `A` | Hexadecimal floating-point | `1.5f` → `"0x1.8p+0"` |
+
+`nan`, `inf` (lowercase for `e`/`f`/`g`/`a`, uppercase for `E`/`F`/`G`/`A`).
+
+## 8. Escape Sequences and Literal Braces
+
+### Literal braces
+
+Because `{` and `}` delimit replacement fields, they must be escaped by
+doubling:
+
+| Input | Output |
+|---|---|
+| `{{` | `{` |
+| `}}` | `}` |
+
+```cpp
+etl::format_to(s, "abc{{def");  // "abc{def"
+etl::format_to(s, "}}abc");     // "}abc"
+```
+
+### Debug / escaped presentation (`?`)
+
+The `?` type specifier produces a debug representation:
+
+- **Characters** are wrapped in single quotes with C-style escape sequences:
+
+  | Character | Output |
+  |---|---|
+  | `\t` | `'\\t'` |
+  | `\n` | `'\\n'` |
+  | `\r` | `'\\r'` |
+  | `"` | `'\\\"'` |
+  | `'` | `'\\''` |
+  | `\\` | `'\\\\'` |
+
+- **Strings** are wrapped in double quotes with the same escape sequences:
+
+  ```cpp
+  etl::format_to(s, "{:?}", "data1\n");  // "\"data1\\n\""
+  ```
+
+## 9. Error Handling
+
+Invalid format strings cause an `etl::bad_format_string_exception` (derived from
+`etl::format_exception`, which is derived from `etl::exception`).
+
+Common error conditions:
+
+| Condition | Example |
+|---|---|
+| Missing closing brace | `"a{b"` |
+| Unescaped `}` without matching `{` | `"a}b"` |
+| Invalid characters inside `{}` | `"a{b}"` |
+| Argument index out of range | `"{1}"` with only one argument |
+| Mixing manual and automatic indexing | `"{0} {}"` |
+| Invalid type specifier for the argument | `"{:d}"` on a `string_view` |
+| Double colon in format spec | `"{::}"` |
+| Precision on an integer | `"{:+#05.5X}"` on an `int` |
+
+```cpp
+etl::string<100> s;
+// These all throw etl::bad_format_string_exception:
+etl::format_to(s, "a{b}",  1);      // bad index spec
+etl::format_to(s, "a{b",   1);      // closing brace missing
+etl::format_to(s, "a}b");           // unescaped }
+etl::format_to(s, "{:d}", sv);      // invalid type for string_view
+```
+
+> **Note:** On C++20 and later, format strings are validated at compile time
+> via `consteval`.  The checks cover syntax (balanced braces, valid format spec
+> grammar, index bounds, no mixing of automatic and manual indexing) as well as
+> type/specifier compatibility (e.g. `{:d}` is rejected for string arguments).
+> A malformed format string produces a compile error whose diagnostic mentions
+> `please_note_this_is_error_message_format_string_syntax_error`.
+>
+> On C++11–C++17, the same checks run at runtime and throw
+> `etl::bad_format_string_exception`.
+
+## 10. Differences from `std::format`
+
+| Area | `std::format` (C++20/23) | ETL |
+|---|---|---|
+| **Output target** | Returns `std::string` | Writes through an output iterator or into `etl::istring&` — no heap allocation. |
+| **`etl::istring&` overload** | Not available | `format_to(etl::istring&, ...)` automatically resizes the string. |
+| **`print` / `println` output** | Writes to `FILE*` / `stdout` | Writes character-by-character via user-defined `etl_putchar(int)`. |
+| **Floating-point support** | Always available | Opt-in via `ETL_USING_FORMAT_FLOATING_POINT`. |
+| **User-defined formatters** | `std::formatter<T>` specialisations | Not yet supported. |
+| **Locale** | `L` flag uses `std::locale` | `L` flag is parsed but has no effect. |
+| **Compile-time validation** | Enforced via `consteval` on C++20 | Enforced via `consteval` on C++20 (syntax and type/specifier compatibility); validates at run time and throws `etl::bad_format_string_exception` on C++11–C++17. |
+| **`format_to_n` return type** | `std::format_to_n_result` | Returns the underlying `OutputIt` directly. |

docs/generators.md

@@ -0,0 +1,190 @@
+# Code Generation for Pre-C++11 Support
+
+ETL supports C++03 (also referred to as C++98) environments where variadic
+templates, `constexpr`, and other modern features are unavailable.  To
+provide equivalent functionality, certain headers are **generated** using
+[Cog](https://nedbatchelder.com/code/cog/), a Python-based code generation
+tool that embeds Python snippets inside source files.
+
+This document explains how the code generation system works and how to
+regenerate the headers if you modify a generator template.
+
+---
+
+## Overview
+
+| Directory | Contents |
+|---|---|
+| `include/etl/generators/` | Generator templates (`*_generator.h`) and batch scripts |
+| `include/etl/private/` | Generated output (`*_cpp03.h`) committed to the repository |
+| `scripts/generator_test.py` | CI script that verifies generators match committed files |
+
+The generator templates contain embedded Python code (delimited by `[[[cog`
+and `]]]`) that produces the repetitive C++03 boilerplate.  Cog processes
+these templates and writes the expanded output to `include/etl/private/`.
+
+---
+
+## Generated Headers
+
+The following C++03 compatibility headers are generated:
+
+| Generator | Output | Purpose |
+|---|---|---|
+| `fsm_fwd_decl_cpp03_generator.h` | `fsm_fwd_decl_cpp03.h` | FSM forward declarations |
+| `fsm_friend_decl_cpp03_generator.h` | `fsm_friend_decl_cpp03.h` | FSM friend declarations |
+| `fsm_cpp03_generator.h` | `fsm_cpp03.h` | Finite state machine implementation |
+| `message_router_cpp03_generator.h` | `message_router_cpp03.h` | Message router |
+| `message_packet_cpp03_generator.h` | `message_packet_cpp03.h` | Message packet |
+| `largest_type_cpp03_generator.h` | `largest_type_cpp03.h` | Largest type metafunction |
+| `largest_alignment_cpp03_generator.h` | `largest_alignment_cpp03.h` | Largest alignment metafunction |
+| `largest_cpp03_generator.h` | `largest_cpp03.h` | Largest type/size utilities |
+| `smallest_cpp03_generator.h` | `smallest_cpp03.h` | Smallest type/size utilities |
+| `type_traits_cpp03_generator.h` | `type_traits_cpp03.h` | Type traits (`is_one_of`, etc.) |
+| `type_lookup_cpp03_generator.h` | `type_lookup_cpp03.h` | Type lookup metafunction |
+| `type_select_cpp03_generator.h` | `type_select_cpp03.h` | Type selection metafunction |
+| `variant_pool_cpp03_generator.h` | `variant_pool_cpp03.h` | Variant pool |
+
+---
+
+## Generator Parameters
+
+Cog variables control how many template parameter overloads are generated:
+
+| Variable | Default | Used by |
+|---|---|---|
+| `Handlers` | 16 | FSM and message router generators |
+| `NTypes` | 16 | Type utility generators (largest, smallest, lookup, select, variant pool) |
+| `IsOneOf` | 16 | Type traits generator (`is_one_of`) |
+
+These defaults produce overloads supporting up to 16 types or handlers,
+which is sufficient for most embedded applications while keeping compile
+times reasonable.
+
+---
+
+## Prerequisites
+
+* **Python 3**
+* **cogapp** – install via:
+
+  ```bash
+  pip install cogapp
+  ```
+
+---
+
+## Regenerating Headers
+
+### Using the batch scripts (Windows)
+
+Each generator has a corresponding `.bat` file in `include/etl/generators/`:
+
+```bat
+cd include/etl/generators
+generate.bat          # Regenerate all headers
+generate_fsm.bat      # Regenerate FSM headers only
+generate_smallest.bat # Regenerate smallest_cpp03.h only
+# etc.
+```
+
+### Manual invocation
+
+Run Cog directly from the `include/etl/generators/` directory:
+
+```bash
+cd include/etl/generators
+
+# Example: regenerate smallest_cpp03.h
+python3 -m cogapp -d -e -o../private/smallest_cpp03.h -DNTypes=16 smallest_cpp03_generator.h
+
+# Example: regenerate fsm_cpp03.h
+python3 -m cogapp -d -e -o../private/fsm_cpp03.h -DHandlers=16 fsm_cpp03_generator.h
+```
+
+Cog options used:
+
+| Option | Meaning |
+|---|---|
+| `-d` | Delete the generator markers from output |
+| `-e` | Warn if the input file has no generator markers |
+| `-o<file>` | Write output to the specified file |
+| `-D<var>=<value>` | Define a Cog variable |
+
+### Regenerating all headers
+
+The `generate.bat` script regenerates every header:
+
+```bash
+cd include/etl/generators
+./generate.bat   # Windows
+# or run the commands manually on Linux/macOS
+```
+
+On Linux/macOS you can run the commands from `generate.bat` directly in
+your shell (they are standard `python3 -m cogapp` invocations).
+
+---
+
+## Verifying Generators
+
+After modifying a generator template, verify the output matches the
+committed file:
+
+```bash
+python3 scripts/generator_test.py
+```
+
+This script:
+
+1. Runs Cog on every `*_generator.h` file.
+2. Compares each output against the corresponding file in
+   `include/etl/private/`.
+3. Reports success or failure.
+
+The `generator.yml` GitHub Actions workflow runs this automatically on
+every push and pull request.
+
+---
+
+## How Generators Work
+
+A generator template contains standard C++ code interspersed with Cog
+directives.  For example, from `smallest_cpp03_generator.h`:
+
+```cpp
+/*[[[cog
+import cog
+cog.outl("template <typename T1, ")
+for n in range(2, int(NTypes)):
+    cog.out("typename T%s = void, " % n)
+cog.outl("typename T%s = void>" % int(NTypes))
+]]]*/
+// Generated code appears here after running Cog
+/*[[[end]]]*/
+```
+
+When Cog processes this file with `-DNTypes=16`, the Python code executes
+and outputs the expanded template parameter list supporting 16 types.
+
+---
+
+## Adding a New Generator
+
+1. Create `include/etl/generators/<name>_cpp03_generator.h` with Cog
+   directives.
+2. Add a corresponding entry to `generate.bat`.
+3. Run `generate.bat` (or the equivalent Cog command) to produce
+   `include/etl/private/<name>_cpp03.h`.
+4. Commit both the generator and the generated output.
+5. Verify with `python3 scripts/generator_test.py`.
+
+---
+
+## Troubleshooting
+
+| Problem | Solution |
+|---|---|
+| `ModuleNotFoundError: No module named 'cogapp'` | Install Cog: `pip install cogapp` |
+| Generator output differs from committed file | Regenerate and commit the updated output |
+| Need more than 16 types/handlers | Change `-DNTypes=` or `-DHandlers=` and regenerate |

docs/index.md

@@ -0,0 +1,7 @@
+---
+title: ETL documentation
+---
+
+## Pages
+
+* [Manchester](manchester.md)

docs/manchester.md

@@ -0,0 +1,259 @@
+---
+title: Manchester encoding and decoding
+---
+
+Efficient Manchester encoding and decoding of data. The Manchester code represents a data bit as a sequence of a 'high' and a 'low' value. In software this translates to a conversion from one to two bits, or in a practical situation, from `n` bytes to `n*2` bytes.
+
+## See also
+
+[Manchester code](https://en.wikipedia.org/wiki/Manchester_code)
+
+## Features
+
+- Normal and inverted Manchester encoding
+- Support for multiple encoding chunk sizes: 8-bit, 16-bit and 32-bit
+- Span-based operations or chunk-based operations
+- Constexpr functions for compile-time encoding/decoding
+- Validation of encoded data
+- Chunked span I/O uses little-endian byte order for multi-byte chunks, independent of host platform endianness
+
+## Algorithm background
+
+To encode the value `0b11001100` we must first duplicate all bits to create the value `0b1111000011110000`. We then perform an XOR of this value with the constant `0b1010101010101010` (`0xAAAA`) to obtain the Manchester coded value of `0b1010010110100101`. We have now replaced each `1` bit with the sequence `10` and each `0` bit with the sequence `01`.
+
+### 2. Bit duplication
+
+Bit duplication is achieved with the following steps. This is also called binary interleaving. The example shows encoding of an 8-bit value.
+
+| Step | High Byte          | Low Byte           | Operation                  |
+|------|--------------------|--------------------|----------------------------|
+| 0    | `_ _ _ _ _ _ _ _`  | `A B C D E F G H`  | input value (i)            |
+| 1    | `_ _ _ _ A B C D`  | `_ _ _ _ E F G H`  | `(i \| (i << 4)) & 0x0F0F` |
+| 2    | `_ _ A B _ _ C D`  | `_ _ E F _ _ G H`  | `(i \| (i << 2)) & 0x3333` |
+| 3    | `_ A _ B _ C _ D`  | `_ E _ F _ G _ H`  | `(i \| (i << 1)) & 0x5555` |
+| 4    | `A A B B C C D D`  | `E E F F G G H H`  | `(i \| (i << 1))`          |
+
+This process can be easily extended to 16-bit or 32-bit values by adding additional steps to the bit duplication.
+
+### 3. Manchester Decoding
+
+Manchester decoding is done in a similar, but reversed way.
+
+### 4. Error Detection
+
+Error detection in Manchester coded data is done by comparing 2 neighboring bits. If they are
+equal, then there is an error in the encoded input data.
+
+Comparing all 8 bit pairs in a 16-bit word is done as follows.
+
+| Step | Binary Value | Operation         | Description                                                                                   |
+|------|--------------|-------------------|-----------------------------------------------------------------------------------------------|
+| 1    | `11011000`   | Original          | First bit pair (lsb, 00) is invalid. Last bit pair is also invalid. Other bit pairs are valid |
+| 2    | `01101100`   | Shift right by 1  | Shift the original value right by one bit                                                     |
+| 3    | `10110100`   | XOR               | XOR the original with the shifted value                                                       |
+| 4    | `01010101`   | Mask with 0x55    | Apply mask to isolate bit pairs                                                               |
+| 5    | `00010100`   | Result            | If result is not equal to 0x55, there was an error in the input                               |
+
+## Analysis
+
+Most traditional ways to Manchester encode data consist of a loop over all bits and a nested if-statement to check the value of the current bit. This approach does not scale well to increasing number of bits. The algorithm implemented here contains no conditional code and scales well. Doubling the number of processed bits per step (the chunk size) adds a single row to the bit duplication table. Because of the lack of loops and conditional code, this algorithm is likely to perform better than traditional ones on simple processors or when compiler optimization is disabled. On modern, powerful processors with caches and advanced optimization possibilities this algorithm may not show much benefit. In any case, the performance of the algorithm depends heavily on the processor type, compiler and compiler (optimization) settings.
+
+## API Reference
+
+### Classes
+
+Classes `etl::manchester` and `etl::manchester_inverted` contain static functions for encoding, decoding and validity checking. It is not necessary to instantiate objects of these classes.
+
+#### etl::manchester
+
+```cpp
+typedef manchester_base<private_manchester::manchester_type_normal> manchester;
+```
+
+Manchester encoder using normal encoding (no inversion).
+
+#### etl::manchester_inverted
+
+```cpp
+typedef manchester_base<private_manchester::manchester_type_inverted> manchester_inverted;
+```
+
+Manchester encoder using inverted encoding.
+
+### Encoding Functions
+
+#### Encode single value
+
+```cpp
+template <typename TDecoded>
+static ETL_CONSTEXPR14 typename encoded<TDecoded>::type encode(TDecoded decoded)
+```
+
+Encodes a single value using Manchester encoding.
+
+**Parameters:**
+
+- `decoded`: The value to encode (`uint8_t`, `uint16_t`, or `uint32_t`)
+
+**Returns:**
+
+- The Manchester encoded value (twice the bit width of input)
+
+**Example:**
+
+```cpp
+uint16_t encoded = etl::manchester::encode(0x55);
+```
+
+#### Encode range
+
+```cpp
+template <typename TChunk = uint_least8_t>
+static ETL_CONSTEXPR14 void encode(etl::span<const uint_least8_t> decoded, 
+                                   etl::span<uint_least8_t> encoded)
+```
+
+Encodes a span of data using the specified chunk size.
+
+**Parameters:**
+
+- `decoded`: Source data to encode
+- `encoded`: Destination for encoded data (must be twice the size of `decoded`)
+
+**Template Parameters:**
+
+- `TChunk`: Chunk size for encoding (`uint8_t`, `uint16_t` or `uint32_t`)
+
+**Example:**
+
+```cpp
+std::array<uint8_t, 4> data = {0x12, 0x34, 0x56, 0x78};
+std::array<uint8_t, 8> encoded_data1{};
+std::array<uint8_t, 8> encoded_data2{};
+
+// Encode with TChunk == uint8_t
+etl::manchester::encode(data, encoded_data1);
+
+// Encode with TChunk == uint32_t
+etl::manchester::encode<uint32_t>(data, encoded_data2);
+```
+
+### Decoding Functions
+
+#### Decode single value
+
+```cpp
+template <typename TEncoded>
+static ETL_CONSTEXPR14 typename decoded<TEncoded>::type decode(TEncoded encoded)
+```
+
+Decodes a single Manchester encoded value.
+
+**Parameters:**
+
+- `encoded`: The encoded value to decode (`uint16_t`, `uint32_t`, or `uint64_t`)
+
+**Returns:**
+
+- The Manchester decoded value (half the bit width of input)
+
+**Example:**
+
+```cpp
+uint8_t decoded = etl::manchester::decode(0x5A5A);
+```
+
+#### Decode range
+
+```cpp
+template <typename TChunk = typename private_manchester::encoded<uint_least8_t>::type>
+static ETL_CONSTEXPR14 void decode(etl::span<const uint_least8_t> encoded, 
+                                   etl::span<uint_least8_t> decoded)
+```
+
+Decodes a span of Manchester encoded data.
+
+**Parameters:**
+
+- `encoded`: Source data to decode
+- `decoded`: Destination for decoded data (must be half the size of `encoded`)
+
+**Template Parameters:**
+
+- `TChunk`: Chunk type for decoding (`uint16_t`, `uint32_t`, or `uint64_t`)
+
+**Example:**
+
+```cpp
+std::array<uint8_t, 8> encoded = {/* ... */};
+std::array<uint8_t, 4> decoded1 {};
+std::array<uint8_t, 4> decoded2 {};
+
+// Decode with TChunk == uint16_t
+etl::manchester::decode(encoded, decoded1);
+
+// Decode with TChunk == uint64_t
+etl::manchester::decode<uint64_t>(encoded, decoded2);
+```
+
+### Validation Functions
+
+#### Single value
+
+```cpp
+template <typename TChunk>
+static ETL_CONSTEXPR14 bool is_valid(TChunk encoded)
+```
+
+Validates that a single value contains valid Manchester encoded data.
+
+**Parameters:**
+
+- `encoded`: The encoded value to validate
+
+**Returns:**
+
+- `true` if the value contains valid Manchester encoded data, `false` otherwise
+
+**Example:**
+
+```cpp
+bool valid = etl::manchester::is_valid(0x5A5A);
+```
+
+#### Range
+
+```cpp
+static ETL_CONSTEXPR14 bool is_valid(etl::span<const uint_least8_t> encoded)
+```
+
+Validates that a range contains valid Manchester encoded data.
+
+**Parameters:**
+
+- `encoded`: The range of encoded data to validate
+
+**Returns:**
+
+- `true` if all data is valid Manchester encoding, `false` otherwise
+
+**Example:**
+
+```cpp
+std::array<uint8_t, 8> encoded_data = {/* ... */};
+bool valid = etl::manchester::is_valid(encoded_data);
+```
+
+## Supported Types
+
+### Input/chunk types for encoding
+
+- `uint8_t` → `uint16_t` (if 8-bit types are supported)
+- `uint16_t` → `uint32_t`
+- `uint32_t` → `uint64_t` (if 64-bit types are supported)
+
+### Input/chunk types for decoding
+
+- `uint16_t` → `uint8_t` (if 8-bit types are supported)
+- `uint32_t` → `uint16_t`
+- `uint64_t` → `uint32_t` (if 64-bit types are supported)

docs/meson.md

@@ -0,0 +1,116 @@
+# Building ETL with Meson
+
+## Prerequisites
+
+- [Meson](https://mesonbuild.com/) >= 0.57.0
+- A C++17 compiler (GCC, Clang, or MSVC)
+- [Ninja](https://ninja-build.org/) (default Meson backend)
+
+UnitTest++ is fetched automatically as a Meson subproject — no manual dependency installation is needed.
+
+## Quick Start
+
+```bash
+# Configure (from the project root)
+meson setup builddir
+
+# Build
+meson compile -C builddir
+
+# Run tests
+meson test -C builddir
+```
+
+## Build Options
+
+### ETL project options
+
+| Option              | Type | Default | Description                                                       |
+|---------------------|------|---------|-------------------------------------------------------------------|
+| `use_stl`           | bool | `true`  | Build with STL support. When `false`, defines `ETL_NO_STL`.       |
+| `enable_sanitizer`  | bool | `false` | Enable AddressSanitizer and UndefinedBehaviorSanitizer (GCC/Clang only). |
+
+### Meson built-in options
+
+| Option      | Type   | Default  | Description                                              |
+|-------------|--------|----------|----------------------------------------------------------|
+| `cpp_std`   | string | `c++17`  | C++ standard to compile with (e.g. `c++20`, `c++23`).   |
+| `buildtype` | string | `debug`  | Build type: `plain`, `debug`, `debugoptimized`, `release`, `minsize`. |
+| `werror`    | bool   | `false`  | Treat compiler warnings as errors.                       |
+
+These are handled by Meson directly — no `get_option()` call is needed in the build files.
+
+### Examples
+
+```bash
+# No STL, C++23
+meson setup builddir -Duse_stl=false -Dcpp_std=c++23
+
+# Release build with sanitizers
+meson setup builddir -Dbuildtype=release -Denable_sanitizer=true
+
+# Override the C++ standard on an existing build directory
+meson configure builddir -Dcpp_std=c++20
+```
+
+## Selecting a Compiler
+
+The compiler is chosen at configure time via environment variables:
+
+```bash
+# GCC
+CC=gcc CXX=g++ meson setup builddir
+
+# Clang
+CC=clang CXX=clang++ meson setup builddir
+
+# Specific versions
+CC=gcc-14 CXX=g++-14 meson setup builddir
+CC=clang-18 CXX=clang++-18 meson setup builddir
+```
+
+To switch compilers on an existing build directory, wipe it first:
+
+```bash
+CC=clang CXX=clang++ meson setup --wipe builddir
+```
+
+Or use separate directories per compiler:
+
+```bash
+CC=gcc CXX=g++ meson setup build-gcc
+CC=clang CXX=clang++ meson setup build-clang
+```
+
+## Running Tests
+
+```bash
+# Run all tests
+meson test -C builddir
+
+# Verbose output (shows individual test results)
+meson test -C builddir -v
+
+# Run the test binary directly
+./builddir/test/etl_unit_tests
+```
+
+## Sanitizers
+
+On GCC and Clang, AddressSanitizer and UndefinedBehaviorSanitizer can be enabled via the `enable_sanitizer` option:
+
+```bash
+meson setup builddir -Denable_sanitizer=true
+```
+
+Note: UBSan may prevent certain `constexpr` evaluations involving function pointers from compiling (e.g. in the closure tests). This matches the CMake build, where sanitizers are also opt-in via `ETL_ENABLE_SANITIZER=ON`.
+
+## Using ETL as a Subproject
+
+ETL can be consumed as a Meson subproject. In your project's `subprojects/` directory, create an `etl.wrap` file, then use:
+
+```meson
+etl_dep = dependency('etl', fallback: ['etl', 'etl_dep'])
+```
+
+When built as a subproject, the ETL test suite is not compiled.

docs/ranges.md

@@ -0,0 +1,328 @@
+# ETL C++17 Ranges Implementation
+
+## Overview
+
+The Embedded Template Library provides a C++17-compatible implementation of ranges, inspired by the C++20 ranges library. This implementation enables range-based algorithms and views for embedded and resource-constrained environments where full C++20 support may not be available.
+
+## Features
+
+- **Ranges**: Provides range types and iterator wrappers for composing operations over sequences.
+- **Views**: Includes lightweight, composable views such as `filter_view`, `transform_view`, and `subrange`.
+- **Algorithms**: Supports range-based algorithms compatible with ETL containers and standard containers.
+- **Compatibility**: Designed for C++17, with minimal dependencies and no reliance on C++20 features.
+
+## Getting Started
+
+Include the main header in your project:
+
+```cpp
+#include <etl/ranges.h>
+```
+
+### Example Usage
+
+#### Using Ranges
+
+```cpp
+#include <etl/print.h>
+#include <etl/ranges.h>
+#include <etl/vector.h>
+
+...
+
+  etl::vector<int, 10> data = {6, 1, 3, 3, 2};
+  etl::ranges::sort(data);
+  etl::ranges::for_each(data, [](const int& i){etl::print(" {}", i);});
+```
+
+Output:
+```text
+ 1 2 3 3 6
+```
+
+#### Using Views
+
+```cpp
+#include <etl/print.h>
+#include <etl/ranges.h>
+#include <etl/vector.h>
+
+...
+
+  etl::vector<int, 10> data = {1, 2, 3, 4, 5};
+  auto even = [](int v) { return v % 2 == 0; };
+  auto filtered = etl::ranges::filter_view(data, even);
+  etl::ranges::for_each(filtered, [](const int& i){etl::print(" {}", i);});
+```
+
+Output:
+```text
+ 2 4
+```
+
+#### Transforming Elements
+
+```cpp
+#include <etl/print.h>
+#include <etl/ranges.h>
+#include <etl/vector.h>
+
+...
+
+  etl::vector<int, 10> data = {1, 2, 3, 4, 5};
+  auto squared = etl::ranges::transform_view(data, [](int v) { return v * v; });
+  etl::ranges::for_each(squared, [](const int& i){etl::print(" {}", i);});
+```
+
+Output:
+```text
+ 1 4 9 16 25
+```
+
+#### Composition
+
+Views can be composed using the pipe (`|`) operator, allowing you to chain multiple transformations in a readable, left-to-right style:
+
+```cpp
+#include <etl/print.h>
+#include <etl/ranges.h>
+#include <etl/vector.h>
+
+namespace views = etl::ranges::views;
+
+...
+
+  etl::vector<int, 10> data = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
+
+  auto result = data
+    | views::filter([](const int& v) { return v % 2 == 0; })
+    | views::transform([](const int& v) { return v * v; });
+
+  etl::ranges::for_each(result, [](const int& i){ etl::print(" {}", i); });
+```
+
+Output:
+```text
+ 4 16 36 64 100
+```
+
+This first filters the even numbers and then squares them. Each `|` passes the result of the previous stage as input to the next view adaptor.
+
+## Supported Views
+
+All views are in the `etl::ranges` namespace. Corresponding range adaptor objects are available in `etl::ranges::views`.
+
+### Range Factories
+
+| View | `views::` adaptor | Description |
+|---|---|---|
+| `empty_view<T>` | `views::empty<T>` | A view with no elements. |
+| `single_view` | `views::single` | A view containing exactly one element. |
+| `iota_view` | `views::iota` | A view of sequentially increasing values. |
+| `repeat_view` | `views::repeat` | A view that repeats a value a given number of times. |
+
+### Range Adaptors
+
+| View | `views::` adaptor | Description |
+|---|---|---|
+| `ref_view` | `views::ref` | A non-owning view that wraps a reference to a range. |
+| `owning_view` | `views::owning` | A view that takes ownership of a range via move. |
+| — | `views::all` | Returns the range itself (if already a view), a `ref_view`, or an `owning_view`. |
+| `filter_view` | `views::filter` | Filters elements based on a predicate. |
+| `transform_view` | `views::transform` | Applies a transformation to each element. |
+| `as_rvalue_view` | `views::as_rvalue` | Casts each element to an rvalue reference. |
+| `as_const_view` | `views::as_const` | Provides a const view of the elements. |
+| `cache_latest_view` | `views::cache_latest` | Caches the most recently accessed element (avoids recomputation). |
+| `reverse_view` | `views::reverse` | Reverses the order of elements. |
+| `drop_view` | `views::drop` | Skips the first *n* elements. |
+| `drop_while_view` | `views::drop_while` | Skips leading elements while a predicate is true. |
+| `take_view` | `views::take` | Takes the first *n* elements. |
+| `take_while_view` | `views::take_while` | Takes leading elements while a predicate is true. |
+| `join_view` | `views::join` | Flattens a range of ranges into a single range. |
+| `join_with_view` | `views::join_with` | Flattens a range of ranges, inserting a delimiter between each. |
+| `split_view` | `views::split` | Splits a range into subranges around a delimiter pattern. |
+| `lazy_split_view` | `views::lazy_split` | Lazily splits a range by a pattern (inner ranges discovered on iteration). |
+| — | `views::counted` | Creates a view of *n* elements starting from an iterator. |
+| `concat_view` | `views::concat` | Concatenates multiple ranges into a single view. |
+| `zip_view` | `views::zip` | Zips multiple ranges into a view of tuples (length of shortest range). |
+| `zip_transform_view` | `views::zip_transform` | Zips multiple ranges and applies a function to each tuple of elements. |
+| `common_view` | `views::common` | Adapts a view so that its iterator and sentinel types are the same. |
+| `enumerate_view` | `views::enumerate` | Pairs each element with its index, producing tuples of (index, value). |
+| `elements_view` | `views::elements` | Extracts the *N*-th element from each tuple-like value. |
+| `keys_view` | `views::keys` | Alias for `elements_view` with *N*=0 (extracts first element of pairs/tuples). |
+| `values_view` | `views::values` | Alias for `elements_view` with *N*=1 (extracts second element of pairs/tuples). |
+| `adjacent_view` | `views::adjacent` | Produces a view of tuples of *N* adjacent elements (sliding window of tuples). |
+| — | `views::pairwise` | Alias for `views::adjacent<2>`. |
+| `adjacent_transform_view` | `views::adjacent_transform` | Applies a function to each group of *N* adjacent elements. |
+| — | `views::pairwise_transform` | Alias for `views::adjacent_transform<2>`. |
+| `chunk_view` | `views::chunk` | Splits a range into non-overlapping chunks of a given size. |
+| `slide_view` | `views::slide` | Produces overlapping subranges (sliding windows) of a given size. |
+| `chunk_by_view` | `views::chunk_by` | Splits a range into subranges between adjacent elements where a predicate is false. |
+| `stride_view` | `views::stride` | Yields every *N*-th element from the underlying range. |
+| `cartesian_product_view` | `views::cartesian_product` | Produces the Cartesian product of multiple ranges as a view of tuples. |
+| `to_input_view` | `views::to_input` | Downgrades iterator category to input iterator while preserving elements and order. |
+| `subrange` | — | Represents a sub-range defined by an iterator–sentinel pair. |
+
+All views support range-based for-loop iteration and can be composed with the pipe (`|`) operator.
+
+## Supported Algorithms
+
+All algorithms are callable objects in the `etl::ranges` namespace. Each supports both an iterator-pair overload and a range overload (where applicable), and most accept optional projection and comparator arguments.
+
+### Non-modifying Sequence Operations
+
+| Algorithm | Description |
+|---|---|
+| `for_each` | Applies a function to each element in a range. |
+| `for_each_n` | Applies a function to the first *n* elements. |
+| `find` | Finds the first element equal to a value. |
+| `find_if` | Finds the first element satisfying a predicate. |
+| `find_if_not` | Finds the first element not satisfying a predicate. |
+| `find_end` | Finds the last occurrence of a subsequence. |
+| `find_first_of` | Finds the first element matching any in a second range. |
+| `adjacent_find` | Finds the first pair of adjacent equal elements. |
+| `count` | Counts elements equal to a value. |
+| `count_if` | Counts elements satisfying a predicate. |
+| `all_of` | Checks if all elements satisfy a predicate. |
+| `any_of` | Checks if any element satisfies a predicate. |
+| `none_of` | Checks if no elements satisfy a predicate. |
+| `mismatch` | Finds the first position where two ranges differ. |
+| `equal` | Checks if two ranges are equal. |
+| `is_permutation` | Checks if one range is a permutation of another. |
+| `search` | Searches for the first occurrence of a subsequence. |
+| `search_n` | Searches for *n* consecutive copies of a value. |
+| `starts_with` | Checks if a range starts with another range. |
+| `ends_with` | Checks if a range ends with another range. |
+| `lexicographical_compare` | Compares two ranges lexicographically. |
+
+### Fold Operations
+
+| Algorithm | Description |
+|---|---|
+| `fold_left` | Left-folds elements with a binary operation. |
+| `fold_left_with_iter` | Left-folds, returning both the result and an iterator. |
+| `fold_left_first` | Left-folds using the first element as the initial value. |
+| `fold_left_first_with_iter` | Like `fold_left_first`, also returning an iterator. |
+| `fold_right` | Right-folds elements with a binary operation. |
+| `fold_right_last` | Right-folds using the last element as the initial value. |
+
+### Modifying Sequence Operations
+
+| Algorithm | Description |
+|---|---|
+| `copy` | Copies elements to a destination range. |
+| `copy_n` | Copies *n* elements to a destination range. |
+| `copy_if` | Copies elements satisfying a predicate. |
+| `copy_backward` | Copies elements backwards to a destination range. |
+| `move` | Moves elements to a destination range. |
+| `move_backward` | Moves elements backwards to a destination range. |
+| `swap_ranges` | Swaps elements between two ranges. |
+| `replace` | Replaces elements equal to a value. |
+| `replace_if` | Replaces elements satisfying a predicate. |
+| `replace_copy` | Copies, replacing elements equal to a value. |
+| `replace_copy_if` | Copies, replacing elements satisfying a predicate. |
+| `remove` | Removes elements equal to a value. |
+| `remove_if` | Removes elements satisfying a predicate. |
+| `remove_copy` | Copies, omitting elements equal to a value. |
+| `fill` | Fills a range with a value. |
+| `fill_n` | Fills *n* elements with a value. |
+| `generate` | Assigns each element the result of a generator function. |
+| `generate_n` | Assigns *n* elements the result of a generator function. |
+| `iota` | Fills a range with sequentially increasing values. |
+| `unique` | Removes consecutive duplicate elements. |
+| `unique_copy` | Copies, removing consecutive duplicates. |
+| `transform` | Applies a transformation to each element. |
+| `reverse` | Reverses the order of elements. |
+| `reverse_copy` | Copies elements in reverse order. |
+| `rotate` | Rotates elements in a range. |
+| `rotate_copy` | Copies elements with rotation. |
+| `shift_left` | Shifts elements to the left. |
+| `shift_right` | Shifts elements to the right. |
+| `shuffle` | Randomly reorders elements. |
+| `sample` | Selects *n* random elements from a range. |
+
+### Sorting Operations
+
+| Algorithm | Description |
+|---|---|
+| `sort` | Sorts elements in a range. |
+| `stable_sort` | Sorts elements preserving relative order of equivalent elements. |
+| `partial_sort` | Partially sorts a range so that the first *n* elements are sorted. |
+| `partial_sort_copy` | Copies and partially sorts elements. |
+| `nth_element` | Partially sorts so that the *n*-th element is in its sorted position. |
+| `is_sorted` | Checks if a range is sorted. |
+| `is_sorted_until` | Finds the first unsorted element. |
+
+### Partitioning Operations
+
+| Algorithm | Description |
+|---|---|
+| `partition` | Partitions elements by a predicate. |
+| `stable_partition` | Partitions elements, preserving relative order. |
+| `is_partitioned` | Checks if a range is partitioned. |
+| `partition_copy` | Copies elements into two ranges based on a predicate. |
+| `partition_point` | Finds the partition point. |
+
+### Binary Search (on sorted ranges)
+
+| Algorithm | Description |
+|---|---|
+| `lower_bound` | Finds the first element not less than a value. |
+| `upper_bound` | Finds the first element greater than a value. |
+| `equal_range` | Returns the range of elements equal to a value. |
+| `binary_search` | Checks if a sorted range contains a value. |
+
+### Set Operations (on sorted ranges)
+
+| Algorithm | Description |
+|---|---|
+| `includes` | Checks if one sorted range includes another. |
+| `merge` | Merges two sorted ranges. |
+| `inplace_merge` | Merges two consecutive sorted sub-ranges in place. |
+| `set_union` | Computes the union of two sorted ranges. |
+| `set_intersection` | Computes the intersection of two sorted ranges. |
+| `set_difference` | Computes the difference of two sorted ranges. |
+| `set_symmetric_difference` | Computes the symmetric difference of two sorted ranges. |
+
+### Heap Operations
+
+| Algorithm | Description |
+|---|---|
+| `make_heap` | Creates a heap from a range. |
+| `push_heap` | Pushes an element onto a heap. |
+| `pop_heap` | Pops the top element from a heap. |
+| `sort_heap` | Sorts a heap into a sorted range. |
+| `is_heap` | Checks if a range is a heap. |
+| `is_heap_until` | Finds the first element that breaks the heap property. |
+
+### Min/Max Operations
+
+| Algorithm | Description |
+|---|---|
+| `min` | Returns the smaller of two values or the smallest in an initializer list. |
+| `min_element` | Finds the smallest element in a range. |
+| `max` | Returns the larger of two values or the largest in an initializer list. |
+| `max_element` | Finds the largest element in a range. |
+| `minmax` | Returns the smaller and larger of two values. |
+| `minmax_element` | Finds both the smallest and largest elements in a range. |
+| `clamp` | Clamps a value between a minimum and maximum. |
+
+### Permutation Operations
+
+| Algorithm | Description |
+|---|---|
+| `next_permutation` | Generates the next lexicographic permutation. |
+| `prev_permutation` | Generates the previous lexicographic permutation. |
+
+
+## Reference
+
+For reference to the STD implementation, see also:
+
+- Algorithms: https://en.cppreference.com/w/cpp/algorithm.html
+- Ranges/Views: https://en.cppreference.com/w/cpp/ranges.html
+
+## Limitations
+
+- Not all C++20 range features are available due to limitation to C++17. Especially C++20 concepts are not used.
+- Designed for ETL containers but can work with standard containers if compatible with ETL's iterator requirements.

docs/source-formatting.md

@@ -0,0 +1,100 @@
+# Source Formatting
+
+This project uses **clang-format** (version 18) to enforce a consistent coding style
+for C and C++ source files. For convenience, **treefmt** is also configured as a
+single-command wrapper that discovers and formats every file in the tree.
+
+---
+
+## clang-format
+
+### Configuration file
+
+The formatting rules live in [`.clang-format`](../.clang-format) at the repository
+root. The style is based on **LLVM**.
+
+See the `.clang-format` file itself for the complete list.
+
+### Version requirement
+
+clang-format **18** is required.
+The helper script [`scripts/clang-format-wrapper`](../scripts/clang-format-wrapper)
+automatically resolves the correct binary: it first looks for `clang-format-18` on
+`PATH`, then falls back to `clang-format` and verifies that its major version is 18.
+All other tooling in the repo calls this wrapper instead of `clang-format` directly.
+
+### Running clang-format manually
+
+Format every tracked source file in the repository:
+
+```bash
+git ls-files -z \
+            '*.c' '*.cc' '*.cpp' \
+            '*.h' '*.hh' '*.hpp' \
+            ':(exclude)include/etl/generators/*' \
+            ':(exclude)include/etl/private/*_cpp03.h' | xargs -0 scripts/clang-format-wrapper -i --verbose --style=file
+```
+
+You can also format individual files directly:
+
+```bash
+scripts/clang-format-wrapper -i --style=file path/to/file.cpp
+```
+
+---
+
+## treefmt
+
+[treefmt](https://treefmt.com) is a language-agnostic source-tree formatter.
+It reads a single configuration file and dispatches each file to the appropriate
+formatter. In this project, it delegates all C/C++ formatting to the same
+`clang-format-wrapper` described above.
+
+In comparison to calling clang-format directly, it brings a significant speedup.
+
+### Configuration file
+
+The configuration lives in [`.treefmt.toml`](../.treefmt.toml) at the repository root.
+
+### Installing treefmt
+
+treefmt is a standalone Go binary. Install it with any of:
+
+```bash
+# Using the official install script
+curl -fsSL https://raw.githubusercontent.com/numtide/treefmt/main/install.sh | bash
+
+# Or via Homebrew
+brew install treefmt
+
+# Or via Nix
+nix profile install nixpkgs#treefmt2
+```
+
+See the [treefmt documentation](https://treefmt.com) for more options.
+
+### Running treefmt
+
+From the repository root:
+
+```bash
+# Format everything
+treefmt
+
+# Check formatting without modifying files (useful in CI)
+treefmt --fail-on-change
+```
+
+---
+
+## Excluded paths
+
+`.treefmt.toml` excludes generated files under
+`include/etl/generators/`. Do **not** format those files manually via clang-format or treefmt.
+
+## Pre-commit
+
+Before submitting a PR / contribution, run `treefmt --fail-on-change` to catch
+unformatted code before merge.
+
+Alternatively, a plain `treefmt` automatically fixes any issues.

docs/testing.md

@@ -0,0 +1,412 @@
+# Testing ETL
+
+This document describes how to build and run the ETL test suite locally,
+inside Dev Containers, and in CI.
+
+## Table of Contents
+
+1. [Prerequisites](#prerequisites)
+2. [Running Tests Locally (`test/run-tests.sh`)](#running-tests-locally)
+3. [Syntax Checks (`test/run-syntax-checks.sh`)](#syntax-checks)
+4. [Cross-Architecture Testing (`.devcontainer/run-tests.sh`)](#cross-architecture-testing)
+5. [Dev Containers for Native Compilers](#dev-containers-for-native-compilers)
+6. [CMake Options Reference](#cmake-options-reference)
+7. [CI Checks (GitHub Actions)](#ci-checks-github-actions)
+8. [Appveyor (Windows / MSVC)](#appveyor-windows--msvc)
+9. [Code Coverage](#code-coverage)
+10. [Generator Tests (`scripts/generator_test.py`)](#generator-tests)
+
+---
+
+## Prerequisites
+
+* **CMake** ≥ 3.10
+* **GCC** and/or **Clang** (any version supported by the project)
+* **Make** or **Ninja** (build backend)
+* **Docker** (only needed for cross-architecture testing via `.devcontainer/run-tests.sh`)
+* **QEMU user-mode** (installed automatically inside the cross-arch Docker images)
+
+The project is header-only, so there is no library to compile – the build
+step compiles the test binary `etl_tests` which links against a bundled copy
+of **UnitTest++**.
+
+---
+
+## Running Tests Locally
+
+The main entry point for local testing is **`test/run-tests.sh`**.  It
+iterates over a matrix of compiler / configuration combinations, creates a
+temporary `build-make` directory for each one, runs CMake + Make + CTest,
+and reports coloured pass/fail output (also appended to `log.txt`).
+
+### Synopsis
+
+```bash
+cd test
+./run-tests.sh <C++ Standard> [Optimisation] [Threads] [Sanitizer] [Compiler] [Verbose]
+```
+
+| Argument | Values | Default |
+|---|---|---|
+| C++ Standard | `11`, `14`, `17`, `20`, `23`, or `all` | *(required)* |
+| Optimisation | `0`, `1`, `2`, `3` | `0` |
+| Threads | any positive integer | `4` |
+| Sanitizer | `s` (enable) / `n` (disable) | `n` (disabled) |
+| Compiler | `gcc`, `clang` | all compilers |
+| Verbose | `v` (enable) / `n` (disable) | `n` (disabled) |
+
+### Examples
+
+```bash
+# Run all C++17 tests with GCC only, optimisation -O0, 8 threads
+./run-tests.sh 17 0 8 n gcc
+
+# Run every standard with both compilers, sanitizers enabled, verbose
+./run-tests.sh all 0 4 s "" v
+```
+
+### What the script does
+
+For every selected C++ standard the script loops over a built-in list of
+configurations (STL / No STL / Force C++03 / Non-virtual messages / …) for
+each selected compiler.  For every combination it:
+
+1. Creates a fresh `build-make` directory inside the configuration's source
+   subdirectory.
+2. Invokes `cmake` with the appropriate `-D` flags (see
+   [CMake Options Reference](#cmake-options-reference)).
+3. Builds via `cmake --build .` (parallel level controlled by
+   `CMAKE_BUILD_PARALLEL_LEVEL`).
+4. Runs `ctest -V`.
+5. Reports success or failure and removes the build directory.
+
+The script exits immediately on the first compilation or test failure.
+
+### Test configurations exercised
+
+| Compiler | Configuration |
+|---|---|
+| GCC | STL |
+| GCC | STL – Non-virtual messages |
+| GCC | STL – Force C++03 |
+| GCC | No STL |
+| GCC | No STL – Force C++03 |
+| GCC | No STL – Builtin mem functions |
+| Clang | STL |
+| Clang | STL – Force C++03 |
+| Clang | No STL |
+| Clang | No STL – Force C++03 |
+| Clang | No STL – Builtin mem functions |
+| GCC / Clang | Initializer list test |
+| GCC / Clang | Error macros – log_errors, exceptions, log_errors_and_exceptions, assert_function |
+
+---
+
+## Syntax Checks
+
+The script **`test/run-syntax-checks.sh`** performs compilation-only syntax
+checks across multiple C++ standards and configurations.  Unlike
+`run-tests.sh`, it **does not run the test binary** – it only verifies that
+the code compiles successfully.  This is useful for quickly validating that
+header changes do not introduce compilation errors across the supported
+standard/configuration matrix.
+
+### Synopsis
+
+```bash
+cd test
+./run-syntax-checks.sh <C++ Standard> [Threads] [Compiler]
+```
+
+| Argument | Values | Default |
+|---|---|---|
+| C++ Standard | `03`, `11`, `14`, `17`, `20`, `23`, or `a` (all) | *(required)* |
+| Threads | any positive integer | `4` |
+| Compiler | `gcc`, `clang` | all compilers |
+
+### Examples
+
+```bash
+# Check C++17 syntax with GCC only, using 8 threads
+./run-syntax-checks.sh 17 8 gcc
+
+# Check all standards with both compilers
+./run-syntax-checks.sh a
+```
+
+### What the script does
+
+The script operates from the `test/syntax_check` directory and iterates over
+the selected C++ standard(s).  For each standard and compiler combination it:
+
+1. Creates fresh build directories (`bgcc` / `bclang`).
+2. Invokes `cmake` with the appropriate `-D` flags for the configuration.
+3. Builds via `cmake --build`.
+4. Reports compilation success or failure (logged to `log.txt`).
+
+The script exits immediately on the first compilation failure.
+
+### Configurations checked per standard
+
+For each C++ standard the following configurations are compiled:
+
+| Compiler | Configuration |
+|---|---|
+| GCC | STL |
+| GCC | No STL |
+| GCC | STL – Built-in traits |
+| GCC | No STL – Built-in traits |
+| Clang | STL |
+| Clang | No STL |
+| Clang | STL – Built-in traits |
+| Clang | No STL – Built-in traits |
+
+---
+
+## Cross-Architecture Testing
+
+**`.devcontainer/run-tests.sh`** builds and runs the test suite for
+non-x86_64 architectures using Docker and QEMU user-mode emulation.  It is
+designed to be run **from the project root**.
+
+### Supported architectures
+
+| Argument | Target | Endianness | QEMU binary |
+|---|---|---|---|
+| `armhf` | ARM hard-float (32-bit) | Little | `qemu-arm-static` |
+| `i386` | x86 32-bit | Little | `qemu-i386-static` |
+| `powerpc` | PowerPC 32-bit | Big | `qemu-ppc` |
+| `riscv64` | RISC-V 64-bit | Little | `qemu-riscv64-static` |
+| `s390x` | IBM Z (64-bit) | Big | `qemu-s390x-static` |
+
+### Synopsis
+
+```bash
+# From the project root
+.devcontainer/run-tests.sh <architecture>
+```
+
+### How it works
+
+The script has two phases controlled by a second (internal) argument:
+
+1. **Outside the container** (no second argument):
+   * Builds a Docker image from `.devcontainer/<arch>/Dockerfile`.
+   * Starts a container, bind-mounting the project at `/workspaces/etl`.
+   * Re-invokes itself *inside* the container with the `inside_container`
+     flag.
+
+2. **Inside the container** (`inside_container`):
+   * Creates `build-<arch>` and runs CMake with the appropriate cross-
+     compilation toolchain file
+     (`.devcontainer/<arch>/toolchain-<arch>.cmake`).
+   * Builds with `cmake --build .` using all available cores.
+   * Runs the test suite via `ctest --output-on-failure`.
+
+The toolchain files set `CMAKE_CROSSCOMPILING_EMULATOR` so that CTest can
+run the binary transparently through QEMU.
+
+### Example
+
+```bash
+# Build & run the armhf test suite
+.devcontainer/run-tests.sh armhf
+```
+
+The cross-arch containers build with the following fixed settings:
+
+* C++23, No STL, sanitizer off, optimisation -O0.
+
+---
+
+## Dev Containers for Native Compilers
+
+The `.devcontainer/` directory also provides Dev Container definitions for a
+wide range of **native** (x86_64) compiler versions.  These are intended for
+use with **VS Code Dev Containers** or **GitHub Codespaces**.
+
+| Directory | Compiler |
+|---|---|
+| `gcc09` – `gcc15` | GCC 9 through 15 |
+| `clang7` – `clang21` | Clang 7 through 21 |
+
+Each subdirectory contains a `devcontainer.json` that references the shared
+`Dockerfile` (`.devcontainer/Dockerfile`) and passes the appropriate base
+Docker image via the `BASE_IMAGE_NAME` build argument (e.g. `gcc:15`).
+
+The default Dev Container (`.devcontainer/devcontainer.json`) uses the
+Microsoft C++ dev-container base image.
+
+To use one of these containers:
+
+1. Open the repository in VS Code.
+2. **Ctrl+Shift+P → Dev Containers: Reopen in Container** and select the
+   desired configuration (e.g. *Gcc 15*).
+3. Use `test/run-tests.sh` inside the container as described above.
+
+---
+
+## CMake Options Reference
+
+When invoking CMake for the test suite (source directory is `test/`), the
+following `-D` options control the build:
+
+| Option | Type | Description |
+|---|---|---|
+| `BUILD_TESTS` | `BOOL` | Must be `ON` to compile the test binary. |
+| `NO_STL` | `BOOL` | Build without the C++ Standard Library. |
+| `ETL_CXX_STANDARD` | `STRING` | C++ standard: `11`, `14`, `17`, `20`, `23`. |
+| `ETL_OPTIMISATION` | `STRING` | Compiler optimisation flag, e.g. `-O0`. |
+| `ETL_ENABLE_SANITIZER` | `BOOL` | Enable address / undefined-behaviour sanitizers. |
+| `ETL_USE_TYPE_TRAITS_BUILTINS` | `BOOL` | Use compiler built-in type traits. |
+| `ETL_USER_DEFINED_TYPE_TRAITS` | `BOOL` | Use user-defined type traits. |
+| `ETL_FORCE_TEST_CPP03_IMPLEMENTATION` | `BOOL` | Force the C++03 code paths even on newer standards. |
+| `ETL_MESSAGES_ARE_NOT_VIRTUAL` | `BOOL` | Use non-virtual message types. |
+| `ETL_USE_BUILTIN_MEM_FUNCTIONS` | `BOOL` | Use built-in memory functions in No-STL mode. |
+| `CMAKE_TOOLCHAIN_FILE` | `PATH` | Toolchain file for cross-compilation. |
+
+### Minimal manual build example
+
+```bash
+cd test
+mkdir build && cd build
+cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_CXX_STANDARD=20 ..
+cmake --build . -j$(nproc)
+ctest -V
+```
+
+---
+
+## CI Checks (GitHub Actions)
+
+Every push or pull request to `master`, `development`, or `pull-request/*`
+branches triggers a comprehensive set of GitHub Actions workflows defined in
+`.github/workflows/`.
+
+### Workflow matrix
+
+| Workflow file | Compiler | Standard | Notes |
+|---|---|---|---|
+| `gcc-c++11.yml` | GCC | C++11 | STL, No STL, Force C++03 |
+| `gcc-c++14.yml` | GCC | C++14 | STL, No STL, Force C++03 |
+| `gcc-c++17.yml` | GCC | C++17 | STL, No STL, Force C++03 |
+| `gcc-c++20.yml` | GCC | C++20 | STL, No STL, Force C++03 |
+| `gcc-c++23.yml` | GCC | C++23 | STL, No STL, Force C++03 |
+| `clang-c++11.yml` | Clang | C++11 | STL, No STL, Force C++03 |
+| `clang-c++14.yml` | Clang | C++14 | STL, No STL, Force C++03 |
+| `clang-c++17.yml` | Clang | C++17 | STL, No STL, Force C++03 |
+| `clang-c++20.yml` | Clang | C++20 | STL, No STL, Force C++03 |
+| `clang-c++23.yml` | Clang | C++23 | STL, No STL, Force C++03 |
+| `gcc-syntax-checks.yml` | GCC | C++03 – C++23 | Compilation-only syntax checks (no tests run) |
+| `clang-syntax-checks.yml` | Clang | C++03 – C++23 | Compilation-only syntax checks (no tests run) |
+| `msvc.yml` | MSVC 2022 | C++17 | Windows, STL & No STL |
+| `gcc-c++23-armhf.yml` | GCC cross | C++23 | armhf via QEMU |
+| `gcc-c++23-i386.yml` | GCC cross | C++23 | i386 via QEMU |
+| `gcc-c++23-powerpc.yml` | GCC cross | C++23 | powerpc via QEMU |
+| `gcc-c++23-riscv64.yml` | GCC cross | C++23 | RISC-V 64 via QEMU |
+| `gcc-c++23-s390x.yml` | GCC cross | C++23 | s390x via QEMU |
+| `coverage.yml` | GCC | — | Generates lcov coverage report, deploys to GitHub Pages |
+| `generator.yml` | — | — | Runs the code generator |
+| `platformio-update.yml` | — | — | PlatformIO registry update |
+
+### Typical CI job structure
+
+Each compiler/standard workflow follows the same pattern:
+
+1. **Checkout** – `actions/checkout@v4`.
+2. **Build** – set `CC`/`CXX`, call `cmake` with the appropriate `-D` flags,
+   then `make -j`.
+3. **Run tests** – execute `./test/etl_tests -v` (or `ctest -V` for cross-
+   arch jobs).
+
+The cross-architecture CI jobs additionally install a cross-compiler
+toolchain and QEMU inside a `debian:trixie` container, use the matching
+toolchain file from `.devcontainer/<arch>/`, and run tests via CTest (which
+delegates to QEMU through `CMAKE_CROSSCOMPILING_EMULATOR`).
+
+### Branches tested
+
+* `master`
+* `development`
+* `pull-request/*`
+
+All workflows run on both `push` and `pull_request` events (types: opened,
+synchronize, reopened).
+
+---
+
+## Appveyor (Windows / MSVC)
+
+The `appveyor.yml` at the repository root provides additional Windows CI
+using **Visual Studio 2022**.  It builds the `master` branch only.
+
+Configurations tested:
+
+* Debug MSVC C++14
+* Debug MSVC C++14 – No STL
+* Debug MSVC C++17
+* Debug MSVC C++17 – No STL
+* Debug MSVC C++20
+* Debug MSVC C++20 – No STL
+
+The build uses the VS 2022 solution file at `test/vs2022/etl.vcxproj`.
+
+---
+
+## Code Coverage
+
+The `coverage.yml` GitHub Actions workflow generates an **lcov** coverage
+report:
+
+1. Runs `test/run-coverage.sh` which builds and tests with GCC coverage
+   flags.
+2. Uploads the HTML report as a build artifact (retained for 30 days).
+3. On pushes to `master`, deploys the report to **GitHub Pages**.
+
+To generate coverage locally:
+
+```bash
+cd test
+./run-coverage.sh
+# Open test/build-coverage/coverage/index.html
+```
+
+---
+
+## Generator Tests
+
+The script **`scripts/generator_test.py`** verifies that the code generators
+in `include/etl/generators/` produce output matching the checked-in header
+files in `include/etl/private/`.
+
+ETL uses [Cog](https://nedbatchelder.com/code/cog/) to generate certain
+repetitive header files (e.g. `delegate.h`, `message_packet.h`).  The
+generator templates live in `include/etl/generators/*_generator.h` and the
+generated output is committed to `include/etl/private/*.h`.  This test
+ensures the two stay in sync.
+
+### Prerequisites
+
+* **Python 3**
+* **cogapp** – install via `pip install cogapp`
+
+### Synopsis
+
+```bash
+python3 scripts/generator_test.py
+```
+
+### What the script does
+
+1. Iterates over every `*_generator.h` file in `include/etl/generators/`.
+2. Runs Cog on each generator, outputting to `build/generator_tmp/`.
+3. Compares each generated file against the corresponding file in
+   `include/etl/private/`.
+4. Reports success if all files match, or failure if any differ.
+
+The script exits with code `0` on success and `1` on failure.
+
+### CI integration
+
+The `generator.yml` GitHub Actions workflow runs this script automatically
+on pushes and pull requests to verify generator consistency.

examples/ArmTimerCallbacks - C++/etl_profile.h

@@ -10,6 +10,6 @@
 #define ETL_CALLBACK_TIMER_USE_ATOMIC_LOCK
 #define ETL_NO_STL
 
-//#include "etl/profiles/auto.h"
+// #include "etl/profiles/auto.h"
 
 #endif

examples/ArmTimerCallbacks - C++/main.cpp

@@ -1,23 +1,23 @@
 
 #include <stdio.h>
 
-//#if (__cplusplus < 201103L)
+// #if (__cplusplus < 201103L)
 extern "C"
 {
-//#endif
-#include "Board_LED.h"     // ::Board Support:LED
+// #endif
 #include "Board_Buttons.h" // ::Board Support:Buttons
-//#if (__cplusplus < 201103L)
+#include "Board_LED.h"     // ::Board Support:LED
+  // #if (__cplusplus < 201103L)
 }
-//#endif
+// #endif
 
-#include "stm32f4xx.h"     // Device header
+#include "stm32f4xx.h" // Device header
 
-#include "etl/function.h"
-#include "etl/callback_timer.h"
-#include "etl/vector.h"
-#include "etl/iterator.h"
 #include "etl/binary.h"
+#include "etl/callback_timer.h"
+#include "etl/function.h"
+#include "etl/iterator.h"
+#include "etl/vector.h"
 
 struct FP
 {
@@ -28,7 +28,7 @@ static etl::vector<FP, 10> power_callbacks;
 
 void register_poweroff_callback(void (*function)())
 {
-  FP fp = { function };
+  FP fp = {function};
   power_callbacks.push_back(fp);
 }
 
@@ -45,38 +45,38 @@ etl::timer::id::type swap_timers;
  * SystemCoreClockConfigure: configure SystemCoreClock using HSI
                              (HSE is not populated on Nucleo board)
  *----------------------------------------------------------------------------*/
-void SystemCoreClockConfigure(void) {
+void SystemCoreClockConfigure(void)
+{
+  RCC->CR |= ((uint32_t)RCC_CR_HSION);    // Enable HSI
+  while ((RCC->CR & RCC_CR_HSIRDY) == 0); // Wait for HSI Ready
 
-  RCC->CR |= ((uint32_t)RCC_CR_HSION);                     // Enable HSI
-  while ((RCC->CR & RCC_CR_HSIRDY) == 0);                  // Wait for HSI Ready
+  RCC->CFGR = RCC_CFGR_SW_HSI;                            // HSI is system clock
+  while ((RCC->CFGR & RCC_CFGR_SWS) != RCC_CFGR_SWS_HSI); // Wait for HSI used as system clock
 
-  RCC->CFGR = RCC_CFGR_SW_HSI;                             // HSI is system clock
-  while ((RCC->CFGR & RCC_CFGR_SWS) != RCC_CFGR_SWS_HSI);  // Wait for HSI used as system clock
+  FLASH->ACR = FLASH_ACR_PRFTEN;       // Enable Prefetch Buffer
+  FLASH->ACR |= FLASH_ACR_ICEN;        // Instruction cache enable
+  FLASH->ACR |= FLASH_ACR_DCEN;        // Data cache enable
+  FLASH->ACR |= FLASH_ACR_LATENCY_5WS; // Flash 5 wait state
 
-  FLASH->ACR  = FLASH_ACR_PRFTEN;                          // Enable Prefetch Buffer
-  FLASH->ACR |= FLASH_ACR_ICEN;                            // Instruction cache enable
-  FLASH->ACR |= FLASH_ACR_DCEN;                            // Data cache enable
-  FLASH->ACR |= FLASH_ACR_LATENCY_5WS;                     // Flash 5 wait state
+  RCC->CFGR |= RCC_CFGR_HPRE_DIV1;  // HCLK = SYSCLK
+  RCC->CFGR |= RCC_CFGR_PPRE1_DIV4; // APB1 = HCLK/4
+  RCC->CFGR |= RCC_CFGR_PPRE2_DIV2; // APB2 = HCLK/2
 
-  RCC->CFGR |= RCC_CFGR_HPRE_DIV1;                         // HCLK = SYSCLK
-  RCC->CFGR |= RCC_CFGR_PPRE1_DIV4;                        // APB1 = HCLK/4
-  RCC->CFGR |= RCC_CFGR_PPRE2_DIV2;                        // APB2 = HCLK/2
-
-  RCC->CR &= ~RCC_CR_PLLON;                                // Disable PLL
+  RCC->CR &= ~RCC_CR_PLLON; // Disable PLL
 
   // PLL configuration:  VCO = HSI/M * N,  Sysclk = VCO/P
-  RCC->PLLCFGR = ( 16ul                   |                // PLL_M =  16
-                 (384ul <<  6U)           |                // PLL_N = 384
-                 (  3ul << 16U)           |                // PLL_P =   8
-                 (RCC_PLLCFGR_PLLSRC_HSI) |                // PLL_SRC = HSI
-                 (  8ul << 24U)            );              // PLL_Q =   8
+  RCC->PLLCFGR = (16ul |                     // PLL_M =  16
+                  (384ul << 6U) |            // PLL_N = 384
+                  (3ul << 16U) |             // PLL_P =   8
+                  (RCC_PLLCFGR_PLLSRC_HSI) | // PLL_SRC = HSI
+                  (8ul << 24U));             // PLL_Q =   8
 
-  RCC->CR |= RCC_CR_PLLON;                                 // Enable PLL
-  while((RCC->CR & RCC_CR_PLLRDY) == 0) __NOP();           // Wait till PLL is ready
+  RCC->CR |= RCC_CR_PLLON;                        // Enable PLL
+  while ((RCC->CR & RCC_CR_PLLRDY) == 0) __NOP(); // Wait till PLL is ready
 
-  RCC->CFGR &= ~RCC_CFGR_SW;                               // Select PLL as system clock source
-  RCC->CFGR |=  RCC_CFGR_SW_PLL;
-  while ((RCC->CFGR & RCC_CFGR_SWS) != RCC_CFGR_SWS_PLL);  // Wait till PLL is system clock src
+  RCC->CFGR &= ~RCC_CFGR_SW; // Select PLL as system clock source
+  RCC->CFGR |= RCC_CFGR_SW_PLL;
+  while ((RCC->CFGR & RCC_CFGR_SWS) != RCC_CFGR_SWS_PLL); // Wait till PLL is system clock src
 }
 
 void StartTimers()
@@ -123,7 +123,7 @@ void LedToggle()
 
 int main()
 {
-  SystemCoreClockConfigure();                              // configure HSI as System Clock
+  SystemCoreClockConfigure(); // configure HSI as System Clock
   SystemCoreClockUpdate();
 
   LED_Initialize();
@@ -131,10 +131,10 @@ int main()
 
   // The LEDs will start flashing fast after 2 seconds.
   // After another 5 seconds they will start flashing slower.
-  short_toggle = callback_timer.register_timer(LedToggle,   50,  etl::timer::mode::REPEATING);
-  long_toggle  = callback_timer.register_timer(LedToggle,   100,  etl::timer::mode::REPEATING);
+  short_toggle = callback_timer.register_timer(LedToggle, 50, etl::timer::mode::REPEATING);
+  long_toggle  = callback_timer.register_timer(LedToggle, 100, etl::timer::mode::REPEATING);
   start_timers = callback_timer.register_timer(StartTimers, 2000, etl::timer::mode::SINGLE_SHOT);
-  swap_timers  = callback_timer.register_timer(SwapTimers,  1500, etl::timer::mode::SINGLE_SHOT);
+  swap_timers  = callback_timer.register_timer(SwapTimers, 1500, etl::timer::mode::SINGLE_SHOT);
 
   SysTick_Config(SystemCoreClock / 1000);
 
@@ -152,7 +152,7 @@ extern "C"
 {
   void SysTick_Handler()
   {
-    const  uint32_t TICK   = 1U;
+    const uint32_t  TICK   = 1U;
     static uint32_t nticks = TICK;
 
     if (callback_timer.tick(nticks))

examples/FunctionInterruptSimulation-Delegates/FunctionInterruptSimulation.cpp

@@ -11,8 +11,8 @@ enum VectorId
   USART1_IRQ_HANDLER  = 52,
   USART2_IRQ_HANDLER  = 53,
   VECTOR_ID_END,
-  VECTOR_ID_OFFSET    = TIM1_CC_IRQ_HANDLER,
-  VECTOR_ID_RANGE     = VECTOR_ID_END - VECTOR_ID_OFFSET
+  VECTOR_ID_OFFSET = TIM1_CC_IRQ_HANDLER,
+  VECTOR_ID_RANGE  = VECTOR_ID_END - VECTOR_ID_OFFSET
 };
 
 typedef etl::delegate_service<VECTOR_ID_RANGE, VECTOR_ID_OFFSET> InterruptVectors;
@@ -91,8 +91,8 @@ public:
 
   // Constructor.
   Uart(int port_id, size_t interruptId)
-    : port_id(port_id),
-      callback(etl::delegate<void(size_t)>::create<Uart, &Uart::InterruptHandler>(*this))
+    : port_id(port_id)
+    , callback(etl::delegate<void(size_t)>::create<Uart, &Uart::InterruptHandler>(*this))
   {
     GetInterruptVectorsInstance().register_delegate(interruptId, callback);
   }
@@ -119,7 +119,8 @@ Uart  uart1(0, USART1_IRQ_HANDLER);
 Uart  uart2(1, USART2_IRQ_HANDLER);
 
 // Declare a global callback for the timer.
-// Uses the most efficient callback type for a class, as everything is known at compile time.
+// Uses the most efficient callback type for a class, as everything is known at
+// compile time.
 etl::delegate<void(size_t)> timer_member_callback = etl::delegate<void(size_t)>::create<Timer, timer, &Timer::InterruptHandler>();
 
 // Declare the callbacks for the free functions.

examples/FunctionInterruptSimulation/FunctionInterruptSimulation.cpp

@@ -1,7 +1,7 @@
 #include <iostream>
 
-#include "etl/function.h"
 #include "etl/callback_service.h"
+#include "etl/function.h"
 
 enum VectorId
 {
@@ -11,8 +11,8 @@ enum VectorId
   USART1_IRQ_HANDLER  = 52,
   USART2_IRQ_HANDLER  = 53,
   VECTOR_ID_END,
-  VECTOR_ID_OFFSET    = TIM1_CC_IRQ_HANDLER,
-  VECTOR_ID_RANGE     = VECTOR_ID_END - VECTOR_ID_OFFSET
+  VECTOR_ID_OFFSET = TIM1_CC_IRQ_HANDLER,
+  VECTOR_ID_RANGE  = VECTOR_ID_END - VECTOR_ID_OFFSET
 };
 
 typedef etl::callback_service<VECTOR_ID_RANGE, VECTOR_ID_OFFSET> InterruptVectors;
@@ -91,8 +91,8 @@ public:
 
   // Constructor.
   Uart(int port_id, int interruptId)
-    : port_id(port_id),
-      callback(*this)
+    : port_id(port_id)
+    , callback(*this)
   {
     GetInterruptVectorsInstance().register_callback(interruptId, callback);
   }
@@ -119,7 +119,8 @@ Uart  uart1(0, USART1_IRQ_HANDLER);
 Uart  uart2(1, USART2_IRQ_HANDLER);
 
 // Declare a global callback for the timer.
-// Uses the most efficient callback type for a class, as everything is known at compile time.
+// Uses the most efficient callback type for a class, as everything is known at
+// compile time.
 etl::function_imp<Timer, size_t, timer, &Timer::InterruptHandler> timer_member_callback;
 
 // Declare the callbacks for the free functions.

examples/MutexMessageRouter/MutexMessageRouter.cpp

@@ -1,13 +1,13 @@
 
-#include <iostream>
-#include <thread>
 #include <atomic>
-#include <string>
 #include <chrono>
+#include <iostream>
+#include <string>
+#include <thread>
 
-#include "etl/mutex.h"
 #include "etl/message.h"
 #include "etl/message_router.h"
+#include "etl/mutex.h"
 
 //*************************************
 struct Message1 : public etl::message<1>
@@ -48,9 +48,7 @@ public:
   }
 
   //*****************
-  void on_receive_unknown(const etl::imessage&)
-  {
-  }
+  void on_receive_unknown(const etl::imessage&) {}
 
   std::string result;
 
@@ -61,7 +59,7 @@ private:
 
 //*************************************
 etl::atomic<bool> start = false;
-Router router;
+Router            router;
 
 //*************************************
 void thread1()
@@ -106,5 +104,3 @@ int main()
 
   return 0;
 }
-
-