clang/test/SemaCXX/int-ptr-cast-SFINAE.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++14
   2 // RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++17
   3
   4 void foo(int* a, int *b) {
   5   a -= b; // expected-error {{incompatible integer to pointer conversion assigning to 'int *' from}}
   6 }
   7
   8 template<typename T> T declval();
   9 struct true_type { static const bool value = true; };
  10 struct false_type { static const bool value = false; };
  11 template<bool, typename T, typename U> struct select { using type = T; };
  12 template<typename T, typename U> struct select<false, T, U> { using type = U; };
  13
  14
  15 template<typename T>
  16 typename select<(sizeof(declval<T>() -= declval<T>(), 1) != 1), true_type, false_type>::type test(...);
  17 template<typename T> false_type test(...);
  18
  19 template<typename T>
  20 static const auto has_minus_assign = decltype(test<T>())::value;
  21
  22 static_assert(has_minus_assign<int*>, "failed"); // expected-error {{static assertion failed due to requirement 'has_minus_assign<int *>': failed}}