http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60209
Bug ID: 60209 Summary: Declaration of user-defined literal operator cause error Product: gcc Version: 4.9.0 Status: UNCONFIRMED Severity: minor Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: kariya_mitsuru at hotmail dot com I think that the sample code below should be compiled successfully. void operator "" "" _x(unsigned long long); According to C++11 standard 2.2[lex.phases], string literal concatenation occurs in compilation phase 6 and syntax analysis is performed in compilation phase 7.