[libc++] Only check for GCC's empty string storage on macOS and iOS
authorLouis Dionne <ldionne@apple.com>
Thu, 12 Nov 2020 16:02:14 +0000 (11:02 -0500)
committerLouis Dionne <ldionne@apple.com>
Fri, 13 Nov 2020 15:48:38 +0000 (10:48 -0500)
commit2728293bbc345a7c80fcd5ee0cc2ac3eac582bc8
tree2b6921357f3326cf0f8aab1d125a174dd020c994
parent6a8099e0f61f5440c6a8b9327d255cb5e09e32b2
[libc++] Only check for GCC's empty string storage on macOS and iOS

We don't need to do that on other Apple platforms, since they never
shipped libstdc++. I also added a comment extracted from the original
commit by Howard Hinnant (e115af2777f6).

Differential Revision: https://reviews.llvm.org/D91359
libcxx/src/include/refstring.h