Bug 11708 – Too much weak typing of std.typecons.Typedef

This code compiles and runs with no errors with dmd 2.065alpha: void main() { import std.typecons: Typedef; alias T = Typedef!int; T x; x = 10; int y = 10; x = y; T[5] arr; arr[0] = 10; } The point of using Typedef is to define a strong type, so I think assigning to it with the original type should not be allowed. And indeed the now deprecated typedef didn't allow it: void main() { typedef int T; int y = 10; T x; x = y; // line 5, error. } temp.d(5): Error: cannot implicitly convert expression (y) of type int to T

That's very comic how Typedef can be too weak for you here but too strong there: https://issues.dlang.org/show_bug.cgi?id=11707 You have to learn what you want bearophile.