https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101725
Bug ID: 101725 Summary: simple requirement of parameter in defaulted non-type template parameter considered non-dependent Product: gcc Version: 11.0 Status: UNCONFIRMED Keywords: rejects-valid Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: johelegp at gmail dot com CC: johelegp at gmail dot com Target Milestone: --- See https://godbolt.org/z/fer6on13z. ```C++ template<class T, bool V = (requires(T t) { x(t); })> constexpr bool can_x_yet{V}; template<class T, bool V = (requires { y(*(T*)(0)); })> constexpr bool can_y_yet{V}; ``` The first line fails with: ``` <source>:1:47: error: parameter 't' may not appear in this context 1 | template<class T, bool V = (requires(T t) { x(t); })> constexpr bool can_x_yet{V}; | ^ <source>:1:45: error: there are no arguments to 'x' that depend on a template parameter, so a declaration of 'x' must be available [-fpermissive] 1 | template<class T, bool V = (requires(T t) { x(t); })> constexpr bool can_x_yet{V}; | ^ <source>:1:45: note: (if you use '-fpermissive', G++ will accept your code, but allowing the use of an undeclared name is deprecated) Compiler returned: 1 ```