clang/test/SemaTemplate/concepts-PR54629.cpp

   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 }