There is a subtle difference between the language used at cppreference.com and by the C++11 Standard regarding when the life of a temporary object is extended (emphasis mine).
From cppreference.com:
Whenever a reference is bound to a temporary or to a base subobject of a temporary, the lifetime of the temporary is extended to match the lifetime of the reference,
From The C++11 Standard:
The second context is when a reference is bound to a temporary. The temporary to which the reference is bound or the temporary that is the complete object of a subobject to which the reference is bound persists for the lifetime of the reference except:
According to the standard, a subject can be a member subject, a base class subject, or an array element.
If we go strictly by the verbiage of the standard in the following sample code
struct Foo
{
Foo() : a(10), b(20) {}
~Foo() { std::cout << "In Foo::~Foo()\n"; }
int a;
int b;
};
Foo getFoo()
{
return Foo();
}
void testFoo1()
{
int const& r = getFoo().a;
std::cout << "In testFoo1()\n";
(void)r; // Shut up the compiler
}
the life time of the object returned by getFoo() should extend for the lifetime of the reference. However, a simple test seems to indicate that it does not.
Is the verbiage used by the standard a defect?
Is the compiler non-conformant?
Is the verbiage used by cppreference.com a defect?
Update
The language used at cppreference.com has been updated to (emphasis mine):
Whenever a reference is bound to a temporary or to a subobject thereof, the lifetime of the temporary is extended to match the lifetime of the reference, with the following exceptions:
