[libcxx-commits] [libcxx] [libc++] Remove explicit mentions of __need_FOO macros (PR #119025)

[Louis Dionne via libcxx-commits]

ldionne wrote:

I am trying to run in a ubuntu Docker image with your sysroot and hitting some failures:

```
$ cmake -S runtimes/ -B build -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;libunwind" -DCMAKE_CXX_COMPILER=clang++-19 -DCMAKE_C_COMPILER=clang-19 -DCMAKE_SYSROOT=/tmp/sysroot-linux -GNinja
-- Performing standalone runtimes build.
CMake Deprecation Warning at /tmp/llvm-project/cmake/Modules/CMakePolicy.cmake:6 (cmake_policy):
  The OLD behavior for policy CMP0116 will be removed from a future version
  of CMake.

  The cmake-policies(7) manual explains that the OLD behaviors of all
  policies are deprecated and that a policy should be set to OLD only under
  specific short-term circumstances.  Projects should be ported to the NEW
  behavior and not rely on setting a policy to OLD.
Call Stack (most recent call first):
  CMakeLists.txt:18 (include)


-- The C compiler identification is Clang 19.1.6
-- The CXX compiler identification is Clang 19.1.6
-- The ASM compiler identification is Clang with GNU-like command-line
-- Found assembler: /usr/bin/clang-19
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - failed
-- Check for working C compiler: /usr/bin/clang-19
-- Check for working C compiler: /usr/bin/clang-19 - broken
CMake Error at /usr/share/cmake-3.28/Modules/CMakeTestCCompiler.cmake:67 (message):
  The C compiler

    "/usr/bin/clang-19"

  is not able to compile a simple test program.

  It fails with the following output:

    Change Dir: '/tmp/llvm-project/build/CMakeFiles/CMakeScratch/TryCompile-vkoXgV'

    Run Build Command(s): /usr/bin/ninja -v cmTC_94ff8
    [1/2] /usr/bin/clang-19 --sysroot=/tmp/sysroot-linux    -MD -MT CMakeFiles/cmTC_94ff8.dir/testCCompiler.c.o -MF CMakeFiles/cmTC_94ff8.dir/testCCompiler.c.o.d -o CMakeFiles/cmTC_94ff8.dir/testCCompiler.c.o -c /tmp/llvm-project/build/CMakeFiles/CMakeScratch/TryCompile-vkoXgV/testCCompiler.c
    [2/2] : && /usr/bin/clang-19 --sysroot=/tmp/sysroot-linux   CMakeFiles/cmTC_94ff8.dir/testCCompiler.c.o -o cmTC_94ff8   && :
    FAILED: cmTC_94ff8
    : && /usr/bin/clang-19 --sysroot=/tmp/sysroot-linux   CMakeFiles/cmTC_94ff8.dir/testCCompiler.c.o -o cmTC_94ff8   && :
    /usr/bin/ld: cannot find crtbeginS.o: No such file or directory
    /usr/bin/ld: cannot find -lgcc: No such file or directory
    /usr/bin/ld: cannot find -lgcc_s: No such file or directory
    clang-19: error: linker command failed with exit code 1 (use -v to see invocation)
    ninja: build stopped: subcommand failed.





  CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
  CMakeLists.txt:23 (project)


-- Configuring incomplete, errors occurred!
```

If you want me to investigate, I'm happy to do that but I'll need a clear reproducer.

https://github.com/llvm/llvm-project/pull/119025