llvm-project

81b20e11 - [libc++] Work around new GCC 15 type_traits builtins that can't be used as Clang's can (#137871)

[libc++] Work around new GCC 15 type_traits builtins that can't be used as Clang's can (#137871) GCC 15 has added builtins for various C++ type traits that Clang already had. Since `__has_builtin(...)` now finds these, the #if branches previously only used for Clang are now used for GCC 15. However, GCC 15 requires that these builtins only be used in type aliases, not in template aliases. For now, just don't use the `__has_builtin(...)` branches under newer GCC versions, so both 14 and 15 work during the transition. This can be cleaned up later to use all the GCC 15 builtins available. Fixed: #137704 Fixed: #117319