(Help needed) CMake-Build fails to create correct *.pot file

[stefanstaffler]

While running a CMake build, I get the following error:

[build] FAILED: src/App.pot
[build] cd <...> && /usr/bin/cmake -E env SOURCE_DATE_EPOCH=1500000000 TZ=UTC <...>/build/_deps/i18ncpp-build/merge/i18n-merge-pot --package=xyz --version= --output=App.pot <...>/build/src/CMakeFiles/App.dir/./app.cpp.o.poc <...>/build/src/CMakeFiles/App.dir/./appwindow.cpp.o.poc <...>/build/src/CMakeFiles/App.dir/./main.cpp.o.poc
[build] terminate called after throwing an instance of 'std::runtime_error'
[build]   what():  Unable to open file

For linking details, I can provide the following of my CMakeLists.txt:

include(FetchContent)
FetchContent_Declare(
    i18ncpp
    GIT_REPOSITORY https://github.com/zauguin/i18n-cpp.git
    GIT_TAG 41f4528
)
FetchContent_MakeAvailable(i18ncpp)

add_executable(App <...>)

<...>

target_use_i18n(App NODOMAIN)

Details about the system installation:

• Ubuntu 22.04.2 LTS
• GCC 12.1.0 x86_64-linux-gnu
• CMake 3.22.1

Some help would be appreciated @zauguin.

[zauguin]

Which CMake generator are you using?

[stefanstaffler]

Which CMake generator are you using?

Currently I use ninja with the version 1.10.1.

[zauguin]

The command line lists multiple .poc files. Do these files exists?

[stefanstaffler]

The command line lists multiple .poc files. Do these files exists?

Those files don't exist and are never created. I only get a .poc file with no name in the root directory of the build folder but this file is empty.

[zauguin]

That sounds like the matching from source file name to object file name fails. In your add_executable line, when listing the source files, are you specifying any paths or just filenames?

[stefanstaffler]

The source files are collected using file(GLOB src CONFIGURE_DEPENDS <path>/*.cpp) and one for the headers as well. Then, they are added to the add_executable line with ${src} and ${headers}.

[zauguin]

That explains a lot, then you are using absolute paths to your source code which breaks the mapping. Does it help it you add RELATIVE "${CMAKE_CURRENT_SOURCE_DIRECTORY}" in front of CONFIGURE_DEPENDS in the file(GLOB command`?

[stefanstaffler]

Adding RELATIVE to the command file hasn't helped. However, listing the source files manually in the add_executable solved the issue.. I also get the *.poc files now but they are all empty.

[zauguin]

I just noticed your remark that the files are empty, I though this had been resolved. Anyway I looked into it and it seems that the check that the attribute exists break in some clang versions. That's a known issue which has been resolved for clang 17 (https://reviews.llvm.org/D144405), but for older versions it requires a workaround.

The unconditional-attribute branch should fix this (by not checking and just always using the attribute), but it comes with the side-effect of generating lots of warnings for other compilers or if the plugin is not loaded. I'll think if I can come up with a better solution.