File: lambda-capture-pack.cpp

package info (click to toggle)
llvm-toolchain-11 1%3A11.0.1-2
  • links: PTS, VCS
  • area: main
  • in suites: bullseye
  • size: 995,808 kB
  • sloc: cpp: 4,767,656; ansic: 760,916; asm: 477,436; python: 170,940; objc: 69,804; lisp: 29,914; sh: 23,855; f90: 18,173; pascal: 7,551; perl: 7,471; ml: 5,603; awk: 3,489; makefile: 2,573; xml: 915; cs: 573; fortran: 503; javascript: 452
file content (25 lines) | stat: -rw-r--r-- 813 bytes parent folder | download | duplicates (7) 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
 
// RUN: %clang_cc1 -std=c++2a -verify %s

template<typename ...T, typename ...Lambda> void check_sizes(Lambda ...L) {
  static_assert(((sizeof(T) == sizeof(Lambda)) && ...));
}

template<typename ...T> void f(T ...v) {
  // Pack expansion of lambdas: each lambda captures only one pack element.
  check_sizes<T...>([=] { (void)&v; } ...);

  // Pack expansion inside lambda: captures all pack elements.
  auto l = [=] { ((void)&v, ...); };
  static_assert(sizeof(l) >= (sizeof(T) + ...));
}

template void f(int, char, double);

namespace PR41576 {
  template <class... Xs> constexpr int f(Xs ...xs) {
    return [&](auto ...ys) { // expected-note {{instantiation}}
      return ((xs + ys), ...); // expected-warning {{unused}}
    }(1, 2);
  }
  static_assert(f(3, 4) == 6); // expected-note {{instantiation}}
}