1 // RUN: %clang_cc1 -std=c++20 -verify %s
2 
3 template <class T>
4 struct A {
5   void primary();
6 };
7 
8 template <class T>
9   requires requires(T &t) { requires sizeof(t) > 4; }
10 struct A<T> {
11   void specialization1();
12 };
13 
14 template <class T>
15   requires requires(T &t) { requires sizeof(t) > 8; }
16 struct A<T> {
17   void specialization2();
18 };
19 
20 int main() {
21   A<char>().primary();
22   A<char[5]>().specialization1();
23   A<char[16]>(); // expected-error {{ambiguous partial specialization}}
24                  // expected-note@10 {{partial specialization matches [with T = char[16]}}
25                  // expected-note@16 {{partial specialization matches [with T = char[16]}}
26 }
27 
28 // Check error messages when no overload with constraints matches.
29 template <class T>
30 void foo()
31   requires requires(T &t) { requires sizeof(t) < 4; }
32 {}
33 
34 template <class T>
35 void foo()
36   requires requires(T &t) { requires sizeof(t) > 4; }
37 {}
38 
39 template <class T>
40 void foo()
41   requires requires(T &t) { requires sizeof(t) > 8; }
42 {}
43 
44 void test() {
45   foo<char[4]>();
46   // expected-error@-1 {{no matching function for call to 'foo'}}
47   // expected-note@30 {{candidate template ignored: constraints not satisfied}}
48   // expected-note@31 {{because 'sizeof (t) < 4' (4 < 4) evaluated to false}}
49   // expected-note@35 {{candidate template ignored: constraints not satisfied}}
50   // expected-note@36 {{because 'sizeof (t) > 4' (4 > 4) evaluated to false}}
51   // expected-note@40 {{candidate template ignored: constraints not satisfied}}
52   // expected-note@41 {{because 'sizeof (t) > 8' (4 > 8) evaluated to false}}
53 
54   foo<char[16]>();
55   // expected-error@-1 {{call to 'foo' is ambiguous}}
56   // expected-note@35 {{candidate function}}
57   // expected-note@40 {{candidate function}}
58 }
59