http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49447
Summary: operator= (and compound assignment ops) does not
perfectly forward
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: lucdan...@free.fr
Created attachment 24549
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24549
Minimal example
An operator= (or compound assignment operator) that perfectly forwards its
argument, like so:
template<typename T>
T&&
operator=(T&& t)
{ return std::forward<T>(t); }
does not behave exactly like a member will:
template<typename T>
T&&
member(T&& t)
{ return std::forward<T>(t); }
In particular, for some types (integral types it seems), when passed an lvalue
reference to const, operator= returns an rvalue reference to const, e.g. long
const& becomes long const&&. This does not happen for e.g. pointer types, class
types or float or double; or when the function is instead declared as e.g.
operator+ (but not operator+=) or as a regular member.
This is using:
gcc version 4.7.0 20110531 (experimental) [trunk revision 174470] (Debian
20110531-1)
Attached is an example which fails to compile from trying to take the address
of the result of operator= and from triggering a static_assert.
