Qt moc fails if sources have same name

[ePirat]

Similar to #3791, the Qt modules fails with moc files that have the same name:

moc_sources = files('main_interface.hpp',
    'dialogs/playlist.cpp',
    'components/playlist/playlist.cpp')

qt5pre_files = qt5.preprocess(moc_sources : moc_sources)

ERROR: Multiple producers for Ninja target "modules/modules@@qt_plugin@sha/playlist.moc". Please rename your targets.

[jpakkane]

The reason this happens is that the generator output name is @BASENAME@ or something similar. If you have two files with identical filenames their @BASENAME@s are the same and thus will collide.

I can't think of what the true and correct solution for this would be. In general it is considered poor form to have many files in your project with the exact same name. It is very confusing because sooner or later you will mix the two up. Obviously renaming files is not a simple solution for you.

A workaround is to compile files with identical names (in this case e.g. dialogs/playlist.cpp) in a helper static library and link that to your final target. It's a bit messy but should at least unblock your work for this.

[ePirat]

Thanks for the suggested workaround, will give it a try.

I agree it can be confusing having files with the same name in different named subfolders, but I do not think meson should force such a restriction upon the user, still. So I think a proper fix for this is needed and especially for the similar problem with resources, where it is probably even more common to have files with same name in subfolders.

[equeim]

@jpakkane Yeah but if you add regular sources with same name Meson will handle it correctly. E.g.

executable('test',
           sources : ['bar.cpp', 'foo/bar.cpp'])

will compile bar.o and foo_bar.o. So moc should generate moc_bar.cpp and mod_foo_bar.cpp.

[jpakkane]

That's because those use a generator and that uses @BASENAME@ which is defined to not have those path segments and people actually depend on that (I think).

[equeim]

Yeah, it will break moc_source and ui_files arguments. Maybe instead of appending directory prefixes to file names Meson should create an actual directory structure (setting correct includes to current directory), like CMake and Waf do. This will solve the issue with same file names for generators too.

[PPPPoint]

Does this promblem solve？