[libc-commits] [libc] [libc] Add LIBC_NAMESPACE_HIDDEN_DECL macro (PR #97109)

[Joseph Huber via libc-commits]

https://github.com/jhuber6 commented:

Okay, I'm thinking that we should just compile everything with `-fvisibility=hidden`. This prevents exposing our internal symbols, as noted in this patch. The public option macro should then carry something like this in `common.h`
```c
#ifdef LIBC_TARGET_IS_GPU
#define LLVM_LIBC_FUNCTION_ATTR [[gnu::visibility("hidden")]]
#else
#define LLVM_LIBC_FUNCTION_ATTR [[gnu::visibility("default")]]
#endif
```

Is this reasonable? I can make a patch for this, or we can update this one.

https://github.com/llvm/llvm-project/pull/97109