clang/test/SemaCXX/cxx2a-explicit-bool-deferred.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++2a %s
   2
   3 template <typename T1, typename T2> struct is_same {
   4   static constexpr bool value = false;
   5 };
   6
   7 template <typename T> struct is_same<T, T> {
   8   static constexpr bool value = true;
   9 };
  10
  11 template <class T, class U>
  12 concept SameHelper = is_same<T, U>::value;
  13 template <class T, class U>
  14 concept same_as = SameHelper<T, U> && SameHelper<U, T>;
  15
  16 namespace deferred_instantiation {
  17 template <class X> constexpr X do_not_instantiate() { return nullptr; }
  18
  19 struct T {
  20   template <same_as<float> X> explicit(do_not_instantiate<X>()) T(X) {}
  21
  22   T(int) {}
  23 };
  24
  25 T t(5);
  26 // expected-error@17{{cannot initialize}}
  27 // expected-note@20{{in instantiation of function template specialization}}
  28 // expected-note@30{{while substituting deduced template arguments}}
  29 // expected-note@30{{in instantiation of function template specialization}}
  30 T t2(5.0f);
  31 } // namespace deferred_instantiation