[libc++] Fix the build with GCC < 10
authorLouis Dionne <ldionne@apple.com>
Fri, 2 Oct 2020 21:30:42 +0000 (17:30 -0400)
committerLouis Dionne <ldionne@apple.com>
Fri, 2 Oct 2020 22:01:48 +0000 (18:01 -0400)
commit04fce1515b7ae2fcf7986d8578c18cfd559c68b2
tree62ef4ce98fbe74bfd297b6b2ad3c7a8c0d62dda6
parentaff896dea13fed04d79bbd1ce20d5e49fec720bc
[libc++] Fix the build with GCC < 10

For now, we still need to support older GCCs, so work around the lack of
__is_constructible on older GCCs.
libcxx/include/type_traits
libcxx/test/std/utilities/meta/meta.unary/meta.unary.prop/is_constructible.pass.cpp