https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105716
Bug ID: 105716 Summary: CTAD failure with member function returning auto as template argument Product: gcc Version: 12.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: j-l.wynen at hotmail dot de Target Milestone: --- gcc 12 fails to compile the following code (tested 12.1 and trunk). Tried with c++17 and c++20. template <class T> struct Func { static auto apply() {} }; template <class T> struct A { T x; }; template <class T> A(T) -> A<T>; int main() { A a{Func<double>::apply}; } with an error of error: 'A<auto (*)()> a' has incomplete type The code compiles fine with gcc 11, 10, and 9 as well as clang and MSCV. Changing static auto apply() {} to static void apply() {} or any other concrete return type (and proper return statement) makes the code compiles. Also, specifying the template argument of A in main makes it compile. https://godbolt.org/z/c9cGnGEPq