llvm-project/clang/test/SemaTemplate/lambda-capture-pack.cpp

26 lines
851 B
C++

// 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 {{left operand of comma operator has no effect}}
}(1, 2);
}
static_assert(f(3, 4) == 6); // expected-note {{instantiation}}
}