clang/test/CXX/expr/expr.const/p8-2a.cpp

   1 // RUN: %clang_cc1 -std=c++20 -verify %s
   2
   3 // expected-no-diagnostics
   4
   5 namespace P1937R2 {
   6 struct N {
   7   constexpr N() {}
   8   N(N const&) = delete;
   9 };
  10
  11 template<typename T> constexpr void bad_assert_copyable() { T t; T t2 = t; }
  12 using ineffective = decltype(bad_assert_copyable<N>());
  13
  14 template<typename T> consteval void assert_copyable() { T t; T t2 = t; }
  15 // Prior to P1937R2 consteval functions were evaluated even in otherwise
  16 // unevaluated context, now this is well-formed.
  17 using check = decltype(assert_copyable<N>());
  18
  19 template<typename T>
  20 __add_rvalue_reference(T) declval();
  21
  22 constexpr auto add1(auto lhs, auto rhs) {
  23     return lhs + rhs;
  24 }
  25 using T = decltype(add1(declval<int>(), declval<int>()));
  26
  27 consteval auto add2(auto lhs, auto rhs) {
  28     return lhs + rhs;
  29 }
  30 using T = decltype(add2(declval<int>(), declval<int>()));
  31 } // namespace P1937R2
  32