[libc++] Remove definition of _LIBCPP_ALIGNOF for GCC in C++03 mode
That definition is known to be potentially incorrect, and we don't support
GCC in C++03 mode anyway.
Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 4f57a126c4e763e3041c04f0b22e91200506dcc6
diff --git a/include/__config b/include/__config
index 3e64694..17e6bfe 100644
--- a/include/__config
+++ b/include/__config
@@ -398,9 +398,7 @@
#elif defined(_LIBCPP_COMPILER_CLANG)
# define _LIBCPP_ALIGNOF(_Tp) _Alignof(_Tp)
#else
-// This definition is potentially buggy, but it's only taken with GCC in C++03,
-// which we barely support anyway. See llvm.org/PR39713
-# define _LIBCPP_ALIGNOF(_Tp) __alignof(_Tp)
+# error "We don't know a correct way to implement alignof(T) in C++03 outside of Clang"
#endif
#define _LIBCPP_PREFERRED_ALIGNOF(_Tp) __alignof(_Tp)