https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61370
Bug ID: 61370 Summary: decltype, enable_if, previous arguments Product: gcc Version: 4.9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: patrick.a.moran at gmail dot com Created attachment 32878 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=32878&action=edit minimal reproduction SFINAE that depednds on the decltype of a previous argument fails to funciton in a member function if the definition is external to the class. The out-of-class definition is reported as having a prototype that does not match any in the class. In the attached test case you can see the error. If you define WORKAROUND, you will see the same code with the definition moved into the class and the error will not recur.