Even in C there can be issues. the nokigiri ruby gem builds (or used to build) libxml and libxslt (which are pure C) with patches making effort in removing a couple of GNUisms.

For C++ we were faced with some issues, so the process we ended up with is:

- build musl, install it in some location

- inject a few GCC libs and linux headers required for C runtime to have the above location be a proper sysroot for clang to use

- build LLVM libc++ and a few libs (e.g libunwind) as static libs against that sysroot using clang, and inject them into the sysroot

- build whatever C++ final product we want against the sysroot using clang, statically linking libc++ in

- for a dynamic lib, remove " "needed" dynamic reference to libc.so in ELF. also, hide all symbols from libc++ and load with bind local so that when loaded the shared lib prefers its internal symbols (which would make it crash if it jumps to another libc++) and does not pollute the symbol namespace with its internal ones (which would make another lib crash if it jumps to the internal libc++)

- for an executable binary instead of a lib, dynamic references may instead need to be altered so that it works for both

It all hinges on musl being a subset of glibc, which is not entirely true either (see the musl website for differences in behaviour, which may or may not matter depending on the piece of software)

See:

https://wiki.musl-libc.org/functional-differences-from-glibc...

https://github.com/DataDog/libddwaf/blob/c6a90d39d93f04ebb5e...