Fix PR39749 - Headers containing just #error harm __has_include.
This patch changes <experimental/foo> to use #warning instead of
is harmful to common feature detection idioms.
We should also consider only emitting the warning when __DEPRECATED is
defined, like we do in the <ext/foo> headers. Users may want to specify
"-Werror=-W#warnings" while still ignoring the libc++ warnings.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@350485 91177308-0d34-0410-b5e6-96231b3b80d8
24 files changed