[Bug preprocessor/103027] Implement warning for homoglyphs in identifiers [CVE-2021-42694]

[dmalcolm at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103027

--- Comment #3 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
For reference, here's a patch to clang-tidy for this (currently under review):
  https://reviews.llvm.org/D112916