Add documentation and testing for
authorRichard Smith <richard@metafoo.co.uk>
Sun, 5 Apr 2020 22:23:53 +0000 (15:23 -0700)
committerRichard Smith <richard@metafoo.co.uk>
Sun, 5 Apr 2020 22:24:49 +0000 (15:24 -0700)
commit7f24db01751da6953782630bb42dcca8a111590b
tree7825ea4964ec6cc8538b1b0548e5ae750583b47f
parenta43e23360657e3df82af6b96b403d1a5a3174744
Add documentation and testing for
2c88a485c71155c19e512f22c54e63ee337282a3.

Also extend it to cover memchr for consistency.
clang/docs/LanguageExtensions.rst
clang/lib/AST/ExprConstant.cpp
clang/test/SemaCXX/constexpr-string.cpp