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// Copyright (C) 2023 johannst
#include <cstdio>
#include <utility>
struct M {};
// -- CONSUMER -----------------------------------------------------------------
void use(M&) {
puts(__PRETTY_FUNCTION__);
}
void use(M&&) {
puts(__PRETTY_FUNCTION__);
}
// -- TESTER -------------------------------------------------------------------
template<typename T>
void wrapper(T&& param) { // forwarding reference
puts(__PRETTY_FUNCTION__);
// PARAM is an lvalue, therefore this always calls use(M&).
use(param);
}
template<typename T>
void fwd_wrapper(T&& param) { // forwarding reference
puts(__PRETTY_FUNCTION__);
// PARAM is an lvalue, but std::forward returns PARAM with the same value
// category as the forwarding reference takes.
use(std::forward<T>(param));
}
// -- MAIN ---------------------------------------------------------------------
int main() {
{
std::puts("==> wrapper rvalue reference");
wrapper(M{});
// calls use(M&).
std::puts("==> wrapper lvalue reference");
struct M m;
wrapper(m);
// calls use(M&).
}
{
std::puts("==> fwd_wrapper rvalue reference");
fwd_wrapper(M{});
// calls use(M&&).
std::puts("==> fwd_wrapper lvalue reference");
struct M m;
fwd_wrapper(m);
// calls use(M&).
}
}
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