Why is Visual Studio 2013 having trouble with this class member decltype?
c++, c++11, decltype, visual-c++, visual-studio-2013
Solution
This is a known bug in VS2013, fixed† in VS2015. The compiler will accept the code if you use a trailing return type instead.
struct C
{
std::vector<int> v;
auto begin() -> decltype(v.begin()) { return v.begin(); }
auto end() -> decltype(v.end()) { return v.end(); }
};
As the bug report says, another work around is by using:
struct C
{
std::vector<int> v;
decltype(std::declval<decltype(v)>().begin()) begin() { return v.begin(); }
decltype(std::declval<decltype(v)>().end()) end() { return v.end(); }
};
But as @BenVoigt points out in the comments, read this answer for why the trailing return type should be the preferred option.
† Search the linked page for C++ decltype of class-member access incompletely implemented
Problem
``` #include <vector> struct C { std::vector<int> v; decltype(v.begin()) begin() { return v.begin(); } decltype(v.end()) end() { return v.end(); } }; ``` Clang++ has no problem, but MSVC 2013 gives the following error: ``` error C2228: left of '.begin' must have class/struct/union ```