I have tested it with clang-17 on OSX too, but the error occurs:
bash-5.2$ gmake -n
cd module-lib && cmake --workflow --preset default --fresh && cmake --build --preset default --target install
cd module-exe && cmake --workflow --preset default --fresh && cmake --build --preset default --target test
cd header-lib && cmake --workflow --preset default --fresh && cmake --build --preset default --target install
cd header-exe && cmake --workflow --preset default --fresh && cmake --build --preset default --target test
TEST_FORCING_MODULE_ERROR=ON gmake working
gmake[1]: Entering directory '/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error'
cd module-lib && cmake --workflow --preset default --fresh && cmake --build --preset default --target install
cd module-exe && cmake --workflow --preset default --fresh && cmake --build --preset default --target test
gmake[1]: Leaving directory '/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error'
bash-5.2$
bash-5.2$ make clean
rm -rf build stagedir
bash-5.2$ gmake failing
TEST_FORCING_MODULE_ERROR=ON gmake working
gmake[1]: Entering directory '/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error'
cd module-lib && cmake --workflow --preset default --fresh && cmake --build --preset default --target install
Executing workflow step 1 of 2: configure preset "default"
Preset CMake variables:
BUILD_SHARED_LIBS="NO"
CMAKE_BUILD_TYPE="Release"
CMAKE_CXX_SCAN_FOR_MODULES:BOOL="TRUE"
CMAKE_CXX_STANDARD="23"
CMAKE_INSTALL_PREFIX:PATH="/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir"
CMAKE_PREFIX_PATH:STRING="/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir"
TEST_FORCING_MODULE_ERROR="ON"
Preset environment variables:
CPM_USE_LOCAL_PACKAGES="NO"
PATH="/Users/clausklein/.local/bin:/usr/local/opt/llvm/bin://Users/clausklein/perl5/bin:/usr/local/opt/net-snmp/bin:/usr/local/opt/coreutils/libexec/gnubin:/usr/local/libexec/bin:/usr/local/opt/curl/bin:/usr/local/opt/libxml2/bin:/usr/local/opt/libxslt/bin:/usr/local/opt/expat/bin:/usr/local/opt/net-snmp/bin:/Users/clausklein/Library/Python/3.9/bin:/usr/local/opt/python/libexec/bin:/usr/local/opt/sqlite/bin:/usr/local/bin:/usr/local/sbin:/Users/clausklein/scripts:/Users/clausklein/bin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/opt/X11/bin:/Library/Apple/usr/bin:/usr/local/MacGPG2/bin:/usr/texbin"
-- The CXX compiler identification is Clang 17.0.6
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/local/opt/llvm/bin/clang++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Success
-- Found Threads: TRUE
-- Using GTest: 1.14.0
CMake Warning at /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/helpers.cmake:108 (message):
TEST_FORCING_MODULE_ERROR
Call Stack (most recent call first):
test-library/CMakeLists.txt:1 (robocin_cpp_library)
-- Configuring done (1.9s)
-- Generating done (0.0s)
-- Build files have been written to: /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/build/module-lib
Executing workflow step 2 of 2: build preset "default"
[4/4] Linking CXX static library test-library/libtest_class.a
[0/1] Install the project...
-- Install configuration: "Release"
-- Installing: /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/include/test-library/test_class.ixx
-- Installing: /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/lib/libtest_class.a
-- Installing: /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/modules/test_class.ixx
-- Installing: /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/modules/test.pcm
-- Installing: /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/lib/cmake/module_lib/module_libConfig.cmake
-- Installing: /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/lib/cmake/module_lib/module_libConfig-release.cmake
-- Installing: /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/lib/cmake/module_lib/cxx_modules/cxx-modules-module_libTargets.cmake
-- Installing: /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/lib/cmake/module_lib/cxx_modules/cxx-modules-module_libTargets-Release.cmake
-- Installing: /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/lib/cmake/module_lib/cxx_modules/target-test_class-Release.cmake
cd module-exe && cmake --workflow --preset default --fresh && cmake --build --preset default --target test
Executing workflow step 1 of 2: configure preset "default"
Preset CMake variables:
BUILD_SHARED_LIBS="NO"
CMAKE_BUILD_TYPE="Release"
CMAKE_CXX_SCAN_FOR_MODULES:BOOL="TRUE"
CMAKE_CXX_STANDARD="23"
CMAKE_INSTALL_PREFIX:PATH="/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir"
CMAKE_PREFIX_PATH:STRING="/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir"
TEST_FORCING_MODULE_ERROR="ON"
Preset environment variables:
CPM_USE_LOCAL_PACKAGES="NO"
PATH="/Users/clausklein/.local/bin:/usr/local/opt/llvm/bin://Users/clausklein/perl5/bin:/usr/local/opt/net-snmp/bin:/usr/local/opt/coreutils/libexec/gnubin:/usr/local/libexec/bin:/usr/local/opt/curl/bin:/usr/local/opt/libxml2/bin:/usr/local/opt/libxslt/bin:/usr/local/opt/expat/bin:/usr/local/opt/net-snmp/bin:/Users/clausklein/Library/Python/3.9/bin:/usr/local/opt/python/libexec/bin:/usr/local/opt/sqlite/bin:/usr/local/bin:/usr/local/sbin:/Users/clausklein/scripts:/Users/clausklein/bin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/opt/X11/bin:/Library/Apple/usr/bin:/usr/local/MacGPG2/bin:/usr/texbin"
-- The CXX compiler identification is Clang 17.0.6
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/local/opt/llvm/bin/clang++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Success
-- Found Threads: TRUE
-- Using GTest: 1.14.0
-- Using module_lib: '/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/lib/cmake/module_lib'
-- Configuring done (2.0s)
-- Generating done (0.0s)
CMake Warning:
Manually-specified variables were not used by the project:
TEST_FORCING_MODULE_ERROR
-- Build files have been written to: /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/build/module-exe
Executing workflow step 2 of 2: build preset "default"
[1/6] Scanning /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/modules/test_class.ixx for CXX dependencies
FAILED: CMakeFiles/module_lib__test_class@synth_800cc612d0fe.dir/9ece086e9bac.bmi.ddi
"/usr/local/Cellar/llvm/17.0.6_1/bin/clang-scan-deps" -format=p1689 -- /usr/local/opt/llvm/bin/clang++ -DPROJECT_PATH=\"/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/module-lib\" -I/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/module-lib -I/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/build/module-lib -O3 -DNDEBUG -std=gnu++23 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk --precompile -x c++ /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/modules/test_class.ixx -c -o CMakeFiles/module_lib__test_class@synth_800cc612d0fe.dir/9ece086e9bac.bmi -MT CMakeFiles/module_lib__test_class@synth_800cc612d0fe.dir/9ece086e9bac.bmi.ddi -MD -MF CMakeFiles/module_lib__test_class@synth_800cc612d0fe.dir/9ece086e9bac.bmi.ddi.d > CMakeFiles/module_lib__test_class@synth_800cc612d0fe.dir/9ece086e9bac.bmi.ddi.tmp && mv CMakeFiles/module_lib__test_class@synth_800cc612d0fe.dir/9ece086e9bac.bmi.ddi.tmp CMakeFiles/module_lib__test_class@synth_800cc612d0fe.dir/9ece086e9bac.bmi.ddi
Error while scanning dependencies for /Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/modules/test_class.ixx:
/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error/stagedir/modules/test_class.ixx:3:10: fatal error: 'gtest/gtest.h' file not found
ninja: build stopped: subcommand failed.
gmake[1]: *** [GNUmakefile:5: working] Error 1
gmake[1]: Leaving directory '/Users/clausklein/Workspace/cpp/cxx20/cmake-module-error'
gmake: *** [GNUmakefile:8: failing] Error 2
bash-5.2$