clang/test/CXX/expr/expr.prim/expr.prim.lambda/expr.prim.lambda.capture/p17.cpp

   1 // RUN: %clang_cc1 -std=c++2a -verify %s
   2
   3 namespace std_example {
   4   namespace std { template<typename T> T &&move(T &); }
   5
   6   void g(...);
   7
   8   template <class... Args> void f(Args... args) {
   9     auto lm = [&, args...] { return g(args...); };
  10     lm();
  11
  12     auto lm2 = [... xs = std::move(args)] { return g(xs...); };
  13     lm2();
  14   }
  15 }
  16
  17 template<typename ...T> constexpr int f(int k, T ...t) {
  18   auto a = [...v = t] (bool b) mutable {
  19     if (!b) {
  20       ((v += 1), ...);
  21       return (__SIZE_TYPE__)0;
  22     }
  23     return (v * ... * 1) + sizeof...(v);
  24   };
  25   for (int i = 0; i != k; ++i)
  26     a(false);
  27   return a(true);
  28 }
  29
  30 static_assert(f(1, 2, 3, 4) == 3 * 4 * 5 + 3);
  31 static_assert(f(5) == 1);
  32
  33 auto q = [...x = 0] {}; // expected-error {{does not contain any unexpanded parameter packs}}
  34
  35 template<typename ...T> constexpr int nested(T ...t) {
  36   return [...a = t] {
  37     return [a...] {
  38       return (a + ...);
  39     }();
  40   }();
  41 }
  42 static_assert(nested(1, 2, 3) == 6);