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
