wrong autocompletion for std::string argument of a function with gcc5

Noticed in 3.6rc1 that autocompletion for std::string function arguments is wrong. For example, if a declare a function

void foo(std::string &s);

and try to define it somewhere else, I type void foo( and then qtc suggests next signature (it's more clear what I mean in the screenshot):

void foo(std::__cxx11::string &s)

This doesn't happening when use string without std:: prefix