[libcxx-commits] [libcxx] [llvm] [libc++] Add support for picolibc and newlib in RUNTIMES_USE_LIBC (PR #147956)

[Alexander Richardson via libcxx-commits]

arichardson wrote:

It looks to me like this will break existing builds that don't define the macro. I think for at least a while there should be a CMake check for picoline.h (and the newlib equivalent) to set these macros correctly and emit a warning to update the build config?

https://github.com/llvm/llvm-project/pull/147956