clang/test/CXX/temp/temp.decls/temp.variadic/init-capture.cpp

   1 // RUN: %clang_cc1 -std=c++2a -verify %s
   2
   3 namespace p3 {
   4   void bar(...);
   5   template <typename... Args> void foo(Args... args) {
   6     (void)[... xs = args] {
   7       bar(xs...);
   8     };
   9   }
  10
  11   void use() {
  12     foo();
  13     foo(1);
  14   }
  15 }
  16
  17 template<typename ...T> void f(T ...t) {
  18   (void)[&...x = t] {
  19     x; // expected-error {{unexpanded parameter pack 'x'}}
  20   };
  21
  22   // Not OK: can't expand 'x' outside its scope.
  23   weird((void)[&...x = t] {
  24     return &x; // expected-error {{unexpanded parameter pack 'x'}}
  25   }...         // expected-error {{does not contain any unexpanded}}
  26   );
  27
  28   // OK, capture only one 'slice' of 'x'.
  29   weird((void)[&x = t] {
  30     return &x;
  31   }...
  32   );
  33
  34   // 'x' is not expanded by the outer '...', but 'T' is.
  35   weird((void)[&... x = t] {
  36     return T() + &x; // expected-error {{unexpanded parameter pack 'x'}}
  37   }...               // expected-error {{does not contain any unexpanded}}
  38   );
  39 }
  40
  41 template<int ...a> constexpr auto x = [...z = a] (auto F) { return F(z...); };
  42 static_assert(x<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; }) == 123);
  43 static_assert(x<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; }) == 124); // expected-error {{failed}} \
  44                                                                                           // expected-note {{evaluates to '123 == 124'}}
  45
  46 template<int ...a> constexpr auto y = [z = a...] (auto F) { return F(z...); }; // expected-error {{must appear before the name of the capture}}
  47 static_assert(y<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; }) == 123);
  48 static_assert(y<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; }) == 124); // expected-error {{failed}} \
  49                                                                                           // expected-note {{evaluates to '123 == 124'}}