Yes, its a bug. This is something new and was voted in the working paper in February 2012 (link). Nicol Bolas makes a good point in that gcc is actually the conforming compiler according to the FDIS approved C++11 standard because the changes to the working paper were made after that.
Great minds think alike ;v) . I submitted a defect report and suggested a change to the standard on this very topic. http://cplusplus.github.com/LWG/lwg-active.html#2089 Also, Luc Danton helped me understand the difficulty: Direct vs uniform initialization in std::allocator. When the EmplaceConstructible (23.2.1 [container.requirements.general]/13) requirement is used to initialize an object, direct-initialization occurs. Initializing an aggregate or … Read more
The compile error for // T t{u}; std::string a; std::string b{a}; Is a combination of four things The draft until not long ago said that if T has an initializer list constructor (std::string has one, taking char elements), that the initializer list is passed itself as an argument. So the argument to the constructor(s) is … Read more
Yes, this behaviour is intended, according to §13.3.1.7 Initialization by list-initialization When objects of non-aggregate class type T are list-initialized (8.5.4), overload resolution selects the constructor in two phases: — Initially, the candidate functions are the initializer-list constructors (8.5.4) of the class T and the argument list consists of the initializer list as a single … Read more