Bug 3756 – std.traits.ReturnType broken for ref returns

import std.traits; ref uint foo(ref uint num) { return num; } pragma(msg, ReturnType!(foo)); // uint, not ref uint.

Type modifiers can't be passed around in the language, but I think there's a separate issue already opened for this. Anyway you can do: import std.traits; ref uint foo(ref uint num) { return num; } void main() { alias FunctionAttribute FA; static assert(functionAttributes!foo & FA.ref_); }