etl/docs/source/meson.md

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Building ETL with Meson	2

Prerequisites

• Meson >= 0.57.0
• A C++17 compiler (GCC, Clang, or MSVC)
• Ninja (default Meson backend)

UnitTest++ is fetched automatically as a Meson subproject — no manual dependency installation is needed.

Quick Start

# 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

# 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:

# 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:

CC=clang CXX=clang++ meson setup --wipe builddir

Or use separate directories per compiler:

CC=gcc CXX=g++ meson setup build-gcc
CC=clang CXX=clang++ meson setup build-clang

Running Tests

# 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:

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:

etl_dep = dependency('etl', fallback: ['etl', 'etl_dep'])

When built as a subproject, the ETL test suite is not compiled.