emscan-deps doesn't recognize -s arguments

[Diyou]

When linking the imported SDL port targets from /tools/ports/SDL3 or SDL2 in cmake emscan-deps fails to parse the command:

[build] error: unknown argument: '-sUSE_SDL=3'

The full command:

[build] "/mnt/e/Workspace/SDLTemplate/.cache/emsdk/upstream/emscripten/emscan-deps" -format=p1689 -- /mnt/e/Workspace/SDLTemplate/.cache/emsdk/upstream/emscripten/em++   -stdlib=libc++  -g -std=gnu++23 -fPIE -sUSE_SDL=3 -x c++ /mnt/e/Workspace/SDLTemplate/Source/main.c++ -c -o CMakeFiles/HelloWorld.dir/Source/main.c++.o -MT CMakeFiles/HelloWorld.dir/Source/main.c++.o.ddi -MD -MF CMakeFiles/HelloWorld.dir/Source/main.c++.o.ddi.d > CMakeFiles/HelloWorld.dir/Source/main.c++.o.ddi.tmp && mv CMakeFiles/HelloWorld.dir/Source/main.c++.o.ddi.tmp CMakeFiles/HelloWorld.dir/Source/main.c++.o.ddi

[eliemichel]

Possible duplicate of #24410
BTW it seems that --use-port is also an issue for emscan-deps, probably related.

[sbc100]

Hmm, with #24410 the issue could be worked around because the -s flags were all actually link-only flags.

In this case the -s flags is also a compiler flag, so I guess we do need some way to have emscan-deps filter out the -s flags.

[eliemichel]

FTR I've spent quite some time trying work this around by overriding the path to emscan-deps to replace it with a custom version, but no matter how hard I try to force the value of CMAKE_CXX_COMPILER_CLANG_SCAN_DEPS, it keeps being ignored and cmake always ends up using the EMSDK_ROOT/emscan-deps. :'(

[sbc100]

I guess the line in cmake/Modules/Platform/Emscripten.cmake that sets CMAKE_CXX_COMPILER_CLANG_SCAN_DEPS is not conditional.. you might need to comment it out if you want to experiment with an alternative (or just modify to point to yours)

[eliemichel]

I did try that, I even tried not to use this toolchain file and manually pointing cmake to emcc instead, and it was still figuring out where to find EMSDK_ROOT/emscan-deps out of the blue :/

[sbc100]

Did you try cleaning the cmake cache files from build directory?

(I'm working a on solution that has emscan-deps parse and skip the -s flags BTW).

[eliemichel]

Yes each time I was starting from scratch

[sbc100]

Well thats certainly very strange. There must be something odd going on because I'm pretty certain the only reference to emscan-deps is in the toolchain file.