http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47999
Summary: [C++0x] auto type deduction works incorrectly in a
function template
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: mimomo...@gmail.com
Created attachment 23554
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23554
Test case
When `auto&&` is initialized with a function return value that is an lvalue
reference, the deduced type should be an lvalue reference.
int& identity(int& i) { return i; }
void f()
{
int i = 0;
auto&& x = identity(i); // x has type `int&`
}
But, in a function template, auto type deduction incorrectly deduces
the type as an rvalue reference.
template <typename T>
void f()
{
int i = 0;
auto&& x = identity(i); // BUG: x has type `int&&`
}
This bug leads to compilation error in gcc 4.5 and 4.6,
because lvalues cannot bind to rvalue references.
In gcc 4.4, the code compiles fine because lvalues are
allowed to bind to rvalue references.
Tested compilers: gcc-4.4.5, 4.5.2, 4.6-20110219.
(This problem was found by Nathan Ridge.)
