https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109018
Bug ID: 109018
Summary: decltype of dependent expressions lookup should be
done only when doing template function definition
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: nickhuang99 at hotmail dot com
Target Milestone: ---
In
cppreference.com(https://en.cppreference.com/w/cpp/language/function_template#Function_template_overloading)
gives this example about dependent expression lookup issue. However, it turns
out only GCC has this parsing issue. Both clang and MSVC can solve this with no
issue.(https://www.godbolt.org/z/9anx871rr)
template<class T>
decltype(g(T())) h(); // decltype(g(T())) is a dependent type
int g(int);
template<class T>
decltype(g(T())) h()
{ // redeclaration of h() uses earlier lookup
return g(T()); // although the lookup here does find g(int)
}
int i = h<int>(); // template argument substitution fails; g(int)
// was not in scope at the first declaration of h()
