Bug#1057838: clang-17: c++ include dir from sysroot unexpectedly in include paths when in wasm c mode

[Israel Galadima]

Dear Maintainers,


are responsible.

40 +    if (!getDriver().SysRoot.empty()) {
41 +        // Second add the generic one.

43 +        // Third the backward one.

45 +    }


for adding only system/c include paths.
I think the c++ include paths should only be added in the methods for adding

paths.


the emscripten sysroot to the include paths which causes the conflict.

I have looked further into this and I think these lines in the patch file at debian/patches/wasm/wasm-sysroot-usr.diff 42 +        addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version); 44 +        addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version + "/backward"); The above lines are adding c++ include paths in the method (WebAssembly::AddClangSystemIncludeArgs) libc++ (WebAssembly::addLibCxxIncludePaths) or libstdc++ (WebAssembly::addLibStdCXXIncludePaths) include Some context on why I need this fixed. I'm updating emscripten in Debian and need to provide pre-compiled libraries to the end user. However, when compiling c files in compiler-rt that include stdatomic.h, an issue arises. The system's stdatomic.h file uses an include_next to select any other stdatomic.h it finds in the include paths, and since there's another stdatomic.h [1] in the c++ include path of the emscripten sysroot, it gets selected. Ideally, the other stdatomic.h shouldn't be seen, but when compiling c files, clang-17 wrongly adds the c++ include directory from 1. https://github.com/emscripten-core/emscripten/blob/main/system/lib/libcxx/include/stdatomic.h

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