1 // { dg-do compile { target c++17 } }
3 template <class T> struct A {
8 template <class T> A(T) -> A<T>; // #3
10 A a (42); // uses #3 to deduce A<int> and initializes with #1
11 A b = a; // uses #2 (not #3) to deduce A<int> and initializes with #2; #2 is more specialized
13 template <class T> A(A<T>) -> A<A<T>>; // #4
15 A b2 = a; // uses #4 to deduce A<A<int>> and initializes with #1; #4 is as specialized as #2
17 template <class,class> struct same;
18 template <class T> struct same<T,T> {};
20 same<decltype(a),A<int>> s1;
21 same<decltype(b),A<int>> s2;
22 same<decltype(b2),A<A<int>>> s3;