Types A!1 and A!1u not considered equal?

[Don]

On 21.10.2011 02:31, Tobias Brandt wrote:
> Consider the following program:
>
>   class A(uint N) {}
>   void foo(uint N)(A!N) {}
>
>   void main()
>   {
>       auto a = new A!1;                           // compiles
>       foo(new A!1);                               // error
>       foo(new A!1u);                              // compiles
>       foo(cast(A!1u) A!1)                         // compiles, but may
>                                                  //   crash at runtime
>       assert(typeid(new A!1) == typeid(new A!1u)) // compiles, fails at runtime
>   }
>
> The second line in main gives the following error:
>
> Error: cannot implicitly convert expression (new A) of type
>         test.A!(1).A to test.A!(N).A
>
> Adding the 'u' makes the code compile without errors. Explicitly
> instantiating foo with !1 or !1u does not change anything.
>
>> From the first line, it is clear that instantiating A!1 is not the
> problem. Apparently A!1 and A!1u are considered distinct types,
> although the template parameter must in both cases be of type uint
> and have value 1 and thus be identical.
>
> What's going on here?
It's a bit similar to bug 1641.