llvm-project

f50d3582 - [clang][modules] giving the __stddef_ headers their own modules can cause redeclaration errors with -fbuiltin-headers-in-system-modules (#84127)

[clang][modules] giving the __stddef_ headers their own modules can cause redeclaration errors with -fbuiltin-headers-in-system-modules (#84127) On Apple platforms, some of the stddef.h types are also declared in system headers. In particular NULL has a conflicting declaration in <sys/_types/_null.h>. When that's in a different module from <__stddef_null.h>, redeclaration errors can occur. Make the \_\_stddef_ headers be non-modular in -fbuiltin-headers-in-system-modules and restore them back to not respecting their header guards. Still define the header guards though. __stddef_max_align_t.h was in _Builtin_stddef_max_align_t prior to the addition of _Builtin_stddef, and it needs to stay in a module because struct's can't be type merged. __stddef_wint_t.h didn't used to have a module, but leave it in it current module since it doesn't really belong to stddef.h.