clang/test/SemaCXX/ctad-copy-init-list-narrowing.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -verify -Wno-unused-value -std=c++20 %s
   2
   3 namespace std {
   4 typedef decltype(sizeof(int)) size_t;
   5
   6 template <typename E>
   7 struct initializer_list {
   8   const E *p;
   9   size_t n;
  10   initializer_list(const E *p, size_t n) : p(p), n(n) {}
  11 };
  12
  13 // Classes to use to reproduce the exact scenario present in #62925.
  14 template<class T, class Y>
  15 class pair {
  16     public:
  17     pair(T f, Y s) {}
  18 };
  19
  20 template<class T, class Y>
  21 class map {
  22     public:
  23     map(std::initializer_list<pair<T, Y>>) {}
  24     map(std::initializer_list<pair<T, Y>>, int a) {}
  25 };
  26
  27 } // namespace std
  28
  29 // This is the almost the exact code that was in issue #62925.
  30 void testOneLevelNesting() {
  31   std::map mOk = {std::pair{5, 'a'}, {6, 'b'}, {7, 'c'}};
  32
  33   // Verify that narrowing conversion is disabled in the first level of nesting.
  34   std::map mNarrow = {std::pair{5, 'a'}, {6.0f, 'b'}, {7, 'c'}}; // expected-error {{type 'float' cannot be narrowed to 'int' in initializer list}} // expected-note {{insert an explicit cast to silence this issue}}
  35 }
  36
  37 void testMultipleLevelNesting() {
  38   std::map aOk = {{std::pair{5, 'c'}, {5, 'c'}}, 5};
  39
  40   // Verify that narrowing conversion is disabled when it is not in a nested
  41   // in another std::initializer_list, but it happens in the most outer one.
  42   std::map aNarrowNested = {{std::pair{5, 'c'}, {5.0f, 'c'}}, 5}; // expected-error {{type 'float' cannot be narrowed to 'int' in initializer list}} // expected-note {{insert an explicit cast to silence this issue}}
  43
  44   // Verify that narrowing conversion is disabled in the first level of nesting.
  45   std::map aNarrow = {{std::pair{5, 'c'}, {5, 'c'}}, 5.0f}; // expected-error {{type 'float' cannot be narrowed to 'int' in initializer list}} // expected-note {{insert an explicit cast to silence this issue}}
  46 }