Anthony Williams <anthony.williamsNOSPAM@anthonyw.cjb.net> writes:
I don't see any problem here. There's no problem getting the rvalue out of source(), or sink(source()) would fail. Furthermore, no compiler I've ever seen will actually make the allowed temporary in that case.
How about
struct X{};
struct Y { std::string s; X x; std::vector<int> v; };
Y ySource();
const X& x=ySource().x;
This strikes me as more likely to cause a copy than a straight-forward binding from an X temporary.
I think the actual problem is one of either interpretation of 8.5.3/5 or overspecification in that very paragraph. If, instead of saying, "A temporary of type ``cv1 T2'' [sic] is created, and a constructor is called to copy the entire rvalue object into the temporary. The reference is bound to the temporary or to a sub-object within the temporary" It said: "A temporary of type ``cv1 T2'' [sic] is constructed using direct initialization from the rvalue object. The reference is bound to the temporary or to a sub-object within the temporary" we'd be home free. -- Dave Abrahams Boost Consulting www.boost-consulting.com