https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89949
Bug ID: 89949 Summary: Internal compiler error with lambda as template argument Product: gcc Version: 9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: john.boyer at tutanota dot com Target Milestone: --- Since C++20 a template parameter type can be any LiteralType that has strong structural equality. Lambdas are classified as a LiteralType since C++17. Reproducible example of the internal compiler error: https://godbolt.org/z/UP3gG2. Relevant cppreference pages: https://en.cppreference.com/w/cpp/language/template_parameters https://en.cppreference.com/w/cpp/named_req/LiteralType