Re: reference to non-const temporary
Greg Herlihy wrote:
The compiler should ignore the operator Foo&() conversion method when
converting a Foo to a Foo&, so whether the method is commented in or
out should make no difference to the compiler. Since a temporary cannot
be passed as a non-const reference parameter, the use() function call
should not compile successfully in both cases. (=A712.3.2/1 prohibits a
conversion method from being called to convert an object to a reference
to the object's type.)
Thanks -- so g++ 4.01 is wrong in this case.
I'm curious -- why aren't temporaries allowed to be passed as non-const
references? It seems slightly arbitrary, since non-const methods can be
called on them anyway. Surely such temporaries are fully constructed
objects. What's the rationale? It seems the restriction is trivially
circumvented using operator=():
struct Foo {};
Foo make() { return Foo(); }
void use(Foo& foo) { }
int main()
{
use(make()); // Fails, as discussed above
use(Foo() = make()); // Compiles
}
Thanks,
Ethan
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