HI, I have a piece of code at http://goo.gl/r2ySE6 Refer to the code, with option of "-O2 -std=c++1y", when we comment out the statement "id<int>;" clang-3.4.1 compiles the code successfully, but g++-4.9.0 compiles failed, where g++ complains that "unresolved overloaded function type", which in turn implies that at the point of calling compose function, id<int> is not instantiated. "3. Unless a function template specialization has been explicitly instantiated or explicitly specialized, *the function template specialization is implicitly instantiated when the specialization is referenced in a context that requires a function definition to exist.* "[temp.inst] At the point of calling the compose function, the function definition for id<int> is required, and so, id<int> should be implicitly instantiated. Based on my argument, it is a bug in g++-4.9.0, but I am not 100% sure of it. Please advice. PS: Yongwei Wu is credited for discovering the problem. == off topic== I think i am going to be pissed off, because of accidentally posting my question to gcc-bugs mail list. I sincerely apologize for it. Sorry.
