https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62187
Bug ID: 62187 Summary: std::string==const char* could compare sizes first Product: gcc Version: 5.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P3 Component: libstdc++ Assignee: unassigned at gcc dot gnu.org Reporter: glisse at gcc dot gnu.org Hello, when I compare 2 basic_string with ==, libstdc++ only uses the optimization of first checking that the sizes are the same (before calling compare) if __is_char<_CharT> and the traits and allocator are the default ones. I don't understand why, but assuming there is a good reason, I believe the optimization should still apply when comparing std::string and const char*. (this applies to __vstring as well) This was noticed in PR 62156, where we also see that std::string("foo") does a memcpy of size 3 then sets the 4th char to '\0', where a single memcpy of size 4 would make sense.