clang/test/SemaTemplate/diagnose-enable-if-t.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
   2 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++14 %s
   3 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++17 %s
   4 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++20 %s
   5
   6 namespace std {
   7   inline namespace __1 {
   8     template<bool, class = void> struct enable_if {};
   9     template<class T> struct enable_if<true, T> { using type = T; };
  10     template<bool B, class T = void> using enable_if_t = typename enable_if<B, T>::type;
  11   }
  12 }
  13
  14 namespace similar_to_user_code {
  15   // expected-note@+2 {{candidate template ignored: requirement 'sizeof(char) != 1' was not satisfied [with T = char]}}
  16   template<class T, class = std::enable_if_t<sizeof(T) != 1>>
  17   void f(T, short);
  18
  19   // expected-note@+2 {{candidate template ignored: requirement 'sizeof(char) != 1' was not satisfied [with T = char]}}
  20   template<class T, std::enable_if_t<sizeof(T) != 1>* = nullptr>
  21   void f(T, int);
  22
  23   // expected-note@+2 {{candidate template ignored: requirement 'sizeof(char) != 1' was not satisfied [with T = char]}}
  24   template<class T>
  25   std::enable_if_t<sizeof(T) != 1, void> f(T, long);
  26
  27   void test() {
  28     f('x', 0); // expected-error{{no matching function}}
  29   }
  30 }
  31
  32 namespace similar_to_libcxx_version_14 {
  33   template<bool, class = void> struct enable_if {};
  34   template<class T> struct enable_if<true, T> { using type = T; };
  35   template<bool B, class T = void> using __enable_if_t = typename enable_if<B, T>::type;
  36
  37   // expected-note@+2 {{candidate template ignored: requirement 'sizeof(char) != 1' was not satisfied [with T = char]}}
  38   template<class T, class = __enable_if_t<sizeof(T) != 1>>
  39   void f(T, short);
  40
  41   // expected-note@+2 {{candidate template ignored: requirement 'sizeof(char) != 1' was not satisfied [with T = char]}}
  42   template<class T, __enable_if_t<sizeof(T) != 1>* = nullptr>
  43   void f(T, int);
  44
  45   // expected-note@+2 {{candidate template ignored: requirement 'sizeof(char) != 1' was not satisfied [with T = char]}}
  46   template<class T>
  47   __enable_if_t<sizeof(T) != 1, void> f(T, long);
  48
  49   void test() {
  50     f('x', 0); // expected-error{{no matching function}}
  51   }
  52 }
  53
  54 namespace similar_to_libcxx_version_13 {
  55   template<bool> struct _MetaBase {};
  56   template<> struct _MetaBase<true> { template<class R> using _EnableIfImpl = R; };
  57   template<bool B, class T = void> using _EnableIf = typename _MetaBase<B>::template _EnableIfImpl<T>;
  58
  59   // expected-note@+2 {{no member named '_EnableIfImpl'}}
  60   template<class T, class = _EnableIf<sizeof(T) != 1>>
  61   void f(T, short);
  62
  63   // expected-note@+2 {{no member named '_EnableIfImpl'}}
  64   template<class T, _EnableIf<sizeof(T) != 1>* = nullptr>
  65   void f(T, int);
  66
  67   // expected-note@+2 {{no member named '_EnableIfImpl'}}
  68   template<class T>
  69   _EnableIf<sizeof(T) != 1, void> f(T, long);
  70
  71   void test() {
  72     f('x', 0); // expected-error{{no matching function}}
  73   }
  74 }
  75
  76 namespace not_all_names_are_magic {
  77   template<bool, class = void> struct enable_if {};
  78   template<class T> struct enable_if<true, T> { using type = T; };
  79   template<bool B, class T = void> using a_pony = typename enable_if<B, T>::type;
  80
  81   // expected-note@-2 {{candidate template ignored: disabled by 'enable_if' [with T = char]}}
  82   template<class T, class = a_pony<sizeof(T) != 1>>
  83   void f(T, short);
  84
  85   // expected-note@-6 {{candidate template ignored: disabled by 'enable_if' [with T = char]}}
  86   template<class T, a_pony<sizeof(T) != 1>* = nullptr>
  87   void f(T, int);
  88
  89   // expected-note@-10 {{candidate template ignored: disabled by 'enable_if' [with T = char]}}
  90   template<class T>
  91   a_pony<sizeof(T) != 1, void> f(T, long);
  92
  93   void test() {
  94     f('x', 0); // expected-error{{no matching function}}
  95   }
  96 }