This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 112e. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
This seems like it should be well-formed:
template <class T> T list(T x); template <class H, class ...T> auto list(H h, T ...args) -> decltype(list(args...)); auto list3 = list(1, 2, 3);
but it isn't, because the second list isn't in scope in its own trailing-return-type; the point of declaration is after the declarator, which includes the trailing-return-type. And since int has no associated namespaces, the call in the return type only sees the first list. G++, EDG and Clang all reject the testcase on this basis.
But this seems like a natural pattern for writing variadic function templates, and we could support it by moving the point of declaration to the ->. This would mean having to deal with a function that only has a placeholder for a return type, but I think we can handle that.
Rationale (February, 2012):
This is a request for an extension to the language and is thus more appropriately addressed by EWG.
This is a breaking change whose benefits and trade-offs need to be carefully analyzed.