This reverts commit bc60cf2368. Doesn't build on Windows and breaks gcc 9 build, see https://reviews.llvm.org/D116203#3722094 and https://reviews.llvm.org/D116203#3722128 Also revert two follow-ups. One fixed a warning added in bc60cf2368, the other makes use of the feature added in bc60cf2368 in libc++: Revert "[libcxx][NFC] utilises compiler builtins for unary transform type-traits" This reverts commit 06a1d917ef. Revert "[Sema] Fix a warning" This reverts commit c85abbe879.
bc60cf2368
06a1d917ef
c85abbe879