Prepare use of import std;

The fmt project use CXX and CC

.github/workflows/linux.yml

@@ -177,7 +177,9 @@ jobs:
     - name: Configure
       working-directory: ${{runner.workspace}}/build
       env:
-        CXX: ${{matrix.cxx}}
+        CXX: ${{ matrix.cxx }}
+        CC: ${{ startsWith(matrix.cxx, 'g++') && replace(matrix.cxx, 'g++', 'gcc') ||
+                replace(matrix.cxx, 'clang++', 'clang') }}
         CXXFLAGS: ${{matrix.cxxflags}} ${{matrix.cxxflags_extra}}
       run: |
         cmake ${{matrix.gen && '-G' || ''}} ${{matrix.gen}} \

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.8...3.28)
+cmake_minimum_required(VERSION 3.8...4.4)
 include_guard(GLOBAL)
 
 # Fallback for using newer policies on CMake <3.12.
@@ -48,7 +48,7 @@ if (FMT_MASTER_PROJECT AND NOT CMAKE_BUILD_TYPE)
     "CMAKE_C_FLAGS used) Debug Release RelWithDebInfo MinSizeRel.")
 endif ()
 
-project(FMT CXX)
+project(FMT LANGUAGES C CXX)
 
 # Determine support for the C++ module scanning and CXX_MODULE File_Sets
 # Requires C++20, CMake >= 3.28 and
@@ -353,6 +353,12 @@ function (add_module_library name)
     endif ()
   endif ()
 
+  if (FMT_IMPORT_STD)
+    target_compile_features(${name} PUBLIC cxx_std_23)
+    target_compile_definitions(${name} PUBLIC FMT_IMPORT_STD)
+    set_target_properties(${name} PROPERTIES CXX_MODULE_STD 1)
+  endif ()
+
   if (${AML_USE_CMAKE_MODULES})
     target_sources(${name} PUBLIC FILE_SET fmt TYPE CXX_MODULES FILES
                                   ${sources})
@@ -520,7 +526,8 @@ if (FMT_INSTALL)
     EXPORT ${targets_export_name}
     DESTINATION ${FMT_CMAKE_DIR}
     NAMESPACE fmt::
-    COMPONENT fmt_core)
+    COMPONENT fmt_core
+    CXX_MODULES_DIRECTORY .)
 
   install(
     FILES "${pkgconfig}"

GNUmakefile

@@ -0,0 +1,50 @@
+# Standard stuff
+
+.SUFFIXES:
+
+MAKEFLAGS+= --no-builtin-rules  # Disable the built-in implicit rules.
+MAKEFLAGS+= --warn-undefined-variables        # Warn when an undefined variable is referenced.
+
+export CC:=gcc-16
+export CXX:=g++-16
+export CXXFLAGS:=-stdlib=libstdc++
+
+.PHONY: all test check clean format find-package-test
+
+all: build
+	ninja -C build all # TODO: all_verify_interface_header_sets
+
+build: GNUmakefile CMakeLists.txt
+	cmake --version # NOTE: v4.4 expected! CK
+	cmake -G Ninja -S . -B build --fresh \
+	  -D CMAKE_SKIP_TEST_ALL_DEPENDENCY=NO \
+	  -D FMT_MODULE=1 -D FMT_IMPORT_STD=1 -D CMAKE_CXX_STANDARD=23 \
+	  -D CMAKE_EXPERIMENTAL_CXX_IMPORT_STD=f35a9ac6-8463-4d38-8eec-5d6008153e7d
+	ln -fs build/compile_commands.json .
+
+find-package-test: install
+	cmake -G Ninja -S test/find-package-test -B build/find-package-build --fresh \
+	  -D FMT_MODULE=1 -D FMT_IMPORT_STD=1 -D CMAKE_CXX_STANDARD=23 \
+	  -D CMAKE_EXPERIMENTAL_CXX_IMPORT_STD=f35a9ac6-8463-4d38-8eec-5d6008153e7d
+	ninja -C build/find-package-build -v
+	ninja -C build/find-package-build -t deps CMakeFiles/module-test.dir/main.cc.o
+	./build/find-package-build/module-test build/find-package-build/*-test
+	
+
+clean:
+	rm -rf build .cache compile_commands.json
+	find . -name .DS_Store -delete
+	find . -name '*~' -delete
+
+format:
+	git ls-files ::*CMakeLists.txt ::*.cmake | xargs cmake-format -i
+
+check: build
+	run-clang-tidy src
+
+test: build
+	ninja -C build $(@)
+
+# Anything we don't know how to build will use this rule.
+% ::
+	ninja -C build $(@)

test/CMakeLists.txt

@@ -26,6 +26,13 @@ function (add_fmt_test name)
   add_executable(${name} ${sources})
   target_link_libraries(${name} ${libs})
 
+  if (ADD_FMT_TEST_MODULE)
+    if (FMT_IMPORT_STD)
+      target_compile_features(${name} PRIVATE cxx_std_23)
+      set_target_properties(${name} PROPERTIES CXX_MODULE_STD 1)
+    endif ()
+  endif ()
+
   if (ADD_FMT_TEST_HEADER_ONLY AND NOT FMT_UNICODE)
     target_compile_definitions(${name} PUBLIC FMT_UNICODE=0)
   endif ()

test/add-subdirectory-test/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.8...3.25)
+cmake_minimum_required(VERSION 3.8...4.4)
 
 project(fmt-test CXX)
 

test/compile-error-test/CMakeLists.txt

@@ -1,6 +1,6 @@
 # Test if compile errors are produced where necessary.
 
-cmake_minimum_required(VERSION 3.8...3.25)
+cmake_minimum_required(VERSION 3.8...4.4)
 project(compile-error-test CXX)
 
 set(fmt_headers
@@ -77,7 +77,7 @@ function (run_tests)
   file(
     WRITE "${CMAKE_CURRENT_BINARY_DIR}/test/CMakeLists.txt"
     "
-    cmake_minimum_required(VERSION 3.8...3.25)
+    cmake_minimum_required(VERSION 3.8...4.4)
     project(tests CXX)
     add_subdirectory(${FMT_DIR} fmt)
     ${cmake_targets}

test/find-package-test/CMakeLists.txt

@@ -1,9 +1,11 @@
-cmake_minimum_required(VERSION 3.8...3.25)
+cmake_minimum_required(VERSION 3.8...4.4)
 
 project(fmt-test)
 
 find_package(FMT REQUIRED)
 
+set(PEDANTIC_COMPILE_FLAGS)
+
 add_executable(library-test main.cc)
 target_link_libraries(library-test fmt::fmt)
 target_compile_options(library-test PRIVATE ${PEDANTIC_COMPILE_FLAGS})
@@ -15,3 +17,14 @@ if (TARGET fmt::fmt-header-only)
   target_compile_options(header-only-test PRIVATE ${PEDANTIC_COMPILE_FLAGS})
   target_include_directories(header-only-test PUBLIC SYSTEM .)
 endif ()
+
+if (TARGET fmt::fmt-module)
+  add_executable(module-test main.cc)
+  target_link_libraries(module-test fmt::fmt-module)
+  target_compile_options(module-test PRIVATE ${PEDANTIC_COMPILE_FLAGS})
+  if (FMT_IMPORT_STD)
+    target_compile_features(module-test PRIVATE cxx_std_23)
+    set_target_properties(module-test PROPERTIES CXX_MODULE_STD 1)
+  endif ()
+  target_include_directories(module-test PUBLIC SYSTEM .)
+endif ()

test/find-package-test/main.cc

@@ -1,4 +1,9 @@
-#include "fmt/format.h"
+#ifdef FMT_IMPORT_STD
+import std;
+import fmt;
+#else
+#  include "fmt/format.h"
+#endif
 
 int main(int argc, char** argv) {
   for (int i = 0; i < argc; ++i) fmt::print("{}: {}\n", i, argv[i]);

test/module-test.cc

@@ -5,16 +5,22 @@
 //
 // For the license information refer to format.h.
 
-#include <bit>
-#include <chrono>
-#include <exception>
-#include <iterator>
-#include <locale>
-#include <memory>
-#include <ostream>
-#include <string>
-#include <string_view>
-#include <system_error>
+// TODO(CK): not usable here!
+#ifdef FMT_IMPORT_STD_ENABLED
+import std;
+#else
+#  include <bit>
+#  include <chrono>
+#  include <exception>
+#  include <iterator>
+#  include <locale>
+#  include <memory>
+#  include <ostream>
+#  include <string>
+#  include <string_view>
+#  include <system_error>
+#endif
+
 #include <gmock/gmock.h>
 
 #if (__has_include(<fcntl.h>) || defined(__APPLE__) || \
@@ -312,9 +318,7 @@ TEST(module_test, fprintf) {
   EXPECT_WRITE(stderr, fmt::fprintf(stderr, "%d", 42), "42");
 }
 
-TEST(module_test, sprintf) {
-  EXPECT_EQ("42", fmt::sprintf("%d", 42));
-}
+TEST(module_test, sprintf) { EXPECT_EQ("42", fmt::sprintf("%d", 42)); }
 
 TEST(module_test, color) {
   EXPECT_EQ("\x1B[30m42\x1B[0m",

test/static-export-test/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.8...3.25)
+cmake_minimum_required(VERSION 3.8...4.4)
 
 project(fmt-link CXX)