Optimize declval for compile times. Patch from Eric Niebler.

This patch implements the C++11 version of declval without requiring a template
instantiation.

See PR27798 for more information. https://llvm.org/bugs/show_bug.cgi?id=27798


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@269991 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed