https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103902
Bug ID: 103902 Summary: Only the addition space between string-literal and identifier in a literal-operator-id will be accepted by GCC where the identifier is not in a basic character set Product: gcc Version: 11.2.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: xmh970252187 at gmail dot com Target Milestone: --- bool operator ""_Ã(unsigned long long){ return true; } The above code is not accepted by GCC. It should be passed around by adding a space between "" and _Ã. However, it is accepted by Clang, and it is not necessary to add that space.