LLVM compilation problem with musl

I'm trying to compile LLVM with musl libc library. The compilation process fails on the following:

    x86_64-linux-musl-g++ -DGTEST_HAS_RTTI=0 -DLLVM_BUILD_GLOBAL_ISEL -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Ilib/Support -I../lib/Support -Iinclude -I../include -fPIC -fvisibility-inlines-hidden -Werror=date-time -std=c++11 -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wno-maybe-uninitialized -Wdelete-non-virtual-dtor -Wno-comment -ffunction-sections -fdata-sections -O3 -DNDEBUG -fno-exceptions -fno-rtti -MD -MT lib/Support/CMakeFiles/LLVMSupport.dir/DynamicLibrary.cpp.o -MF lib/Support/CMakeFiles/LLVMSupport.dir/DynamicLibrary.cpp.o.d -o lib/Support/CMakeFiles/LLVMSupport.dir/DynamicLibrary.cpp.o -c ../lib/Support/DynamicLibrary.cpp
    In file included from ../lib/Support/DynamicLibrary.cpp:111:0:
    ../lib/Support/Unix/DynamicLibrary.inc: In function ‘void* DoSearch(const char*)’:
    ../lib/Support/Unix/DynamicLibrary.inc:102:42: error: invalid conversion from ‘const void*’ to ‘void*’ [-fpermissive]
        if (!strcmp(SymbolName, #SYM)) return &SYM
                                              ^
    ../lib/Support/Unix/DynamicLibrary.inc:109:5: note: in expansion of macro ‘EXPLICIT_SYMBOL’
         EXPLICIT_SYMBOL(stderr);
         ^~~~~~~~~~~~~~~
    ../lib/Support/Unix/DynamicLibrary.inc:102:42: error: invalid conversion from ‘const void*’ to ‘void*’ [-fpermissive]
        if (!strcmp(SymbolName, #SYM)) return &SYM
                                              ^
    ../lib/Support/Unix/DynamicLibrary.inc:110:5: note: in expansion of macro ‘EXPLICIT_SYMBOL’
         EXPLICIT_SYMBOL(stdout);
         ^~~~~~~~~~~~~~~
    ../lib/Support/Unix/DynamicLibrary.inc:102:42: error: invalid conversion from ‘const void*’ to ‘void*’ [-fpermissive]
        if (!strcmp(SymbolName, #SYM)) return &SYM
                                              ^
    ../lib/Support/Unix/DynamicLibrary.inc:111:5: note: in expansion of macro ‘EXPLICIT_SYMBOL’
         EXPLICIT_SYMBOL(stdin);
         ^~~~~~~~~~~~~~~

Have anyone had similar problem? Maybe someone had already successfully compiled LLVM with musl?

All musl-based distros (like Alpine, sabotage, void-musl) should be affected. I think that Rust team had similar problem (https://github.com/rust-lang/rust/issues/28667) and they came up with some kind of workaround for it.

Regards,
Dmitry

Most likely, you mean this particular fix?

https://git.alpinelinux.org/cgit/aports/tree/main/llvm4/llvm-fix-DynamicLibrary-to-build-with-musl-libc.patch?id=HEAD

Indeed, checking #if defined(__GLIBC__) seems to be a better solution that assuming all C libraries on Linux are the same.

-Dimitry

Thank you very much! It seems to solve the problem, only the patch should now be applied to a different file (lib/Support/Unix/DynamicLibrary.inc instead of lib/Support/DynamicLibrary.cpp), it is compiling now.

Regards,
Dmitry

I've submitted https://reviews.llvm.org/D33883 for review.

-Dimitry