This is a follow up on D61634 and the last step to implement http://lists.llvm.org/pipermail/llvm-dev/2019-April/131973.html
This is in the wrong section of the documentation. We could constant-evaluate __builtin_memcpy_inline, I guess, but that isn't the primary purpose, and your patch doesn't implement constant evaluation anyway.
Might make sense to add a new section, if no existing section makes sense.
Sorry about the delayed response, I was traveling.
Not sure putting "memcpy" in this list makes sense. We did add support for constant-evaluating memcpy, but it was separately from the others, so the description of the feature detection is wrong.
It appears that the expected-warning check here is guarded by the #if as well. Moving it after the #endif results in a failing test.
I noticed this as I was trying to use has_feature(builtin_memcpy_inline), but it somehow does not work, even though the compiler clearly supports __builtin_memcpy_inline.
Any idea what's wrong with the __has_feature test?