From: Brian Budge <brian.budge@gmail.com>
To: GCC-help <gcc-help@gcc.gnu.org>
Subject: potential bug regarding rvalue refs?
Date: Wed, 29 Jan 2014 18:58:00 -0000 [thread overview]
Message-ID: <CANjXV6_d5pSxtRzFh8urwuEq-VPft=3THkGxgCD+wNL6rP8Q7Q@mail.gmail.com> (raw)
Hi all -
I have been playing around with universal references and wanted to see
what the difference is between something like
template <typename T>
void f(T t) {
f_impl(std::forward<foo>(t));
}
and
template <typename T>
void f(T &&t) {
f_impl(std::forward<foo>(t));
}
I wrote a quick program to start to try and tease out any differences,
but found some totally unintuitive behaviour that I think may be a
bug?
#include <iostream>
#if 0
struct foo {
int a;
foo(int b) : a(b) {}
};
#else
typedef int foo;
#endif
void f_impl(foo const &a) {
std::cerr << "f by const ref" << std::endl;
}
void f_impl(foo &&a) {
std::cerr << "f by rvalue ref" << std::endl;
}
template <typename T>
void f(T t) {
f_impl(std::forward<foo>(t));
}
void g_impl(foo const &a) {
std::cerr << "g by const ref" << std::endl;
}
void g_impl(foo &&a) {
std::cerr << "g by rvalue ref" << std::endl;
}
template <typename T>
void g(T &&t) {
g_impl(std::forward<foo>(t));
}
int main(int argc, char **args) {
foo lvalue = 5;
f(lvalue);
f(5);
g(lvalue);
g(5);
return 0;
}
When I compile this via g++ 4.8.2, I get the following output:
:./a.out
f by rvalue ref
f by rvalue ref
g by rvalue ref
g by rvalue ref
Although I'm far from an expert with rvalue refs and universal refs,
this seems like a bug to me. Thoughts?
Thanks,
Brian
next reply other threads:[~2014-01-29 18:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-29 18:58 Brian Budge [this message]
2014-01-29 19:40 ` Florian Weimer
2014-01-29 20:10 ` Jonathan Wakely
2014-01-29 20:56 ` Brian Budge
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