1 // PR c++/42623
2 // We should choose f(B) because f(A<undef>) involves applying sizeof to
3 // an incomplete class, so it is removed by SFINAE.
4 // { dg-do link }
5 
6 struct undef;
7 
8 template <typename U, int N = sizeof(U)> struct A { A(int); };
9 template <typename U> void f(A<U>);
10 
BB11 template <typename U> struct B { B(int) { } };
f(B<U>)12 template <typename U> void f(B<U>) { }
13 
main()14 int main()
15 {
16   f<undef>(0);
17 }
18