[Bug c++/106645] [C++23] P2290R3 - Delimited escape sequences

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106645

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 53467
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53467&action=edit
gcc13-pr106645.patch

Untested implementation.