How to test for equality of types?

[Philippe Sigaud]

On Sat, May 19, 2012 at 12:23 PM, Matthias Walter
<xammy at xammy.homelinux.net> wrote:

> I would open a bug report with the following code which is a bit smaller
> than my first wrong version:
>
> =====================
(...)
>  pragma(msg, typeof(w.aliasStruct).Alias.stringof); // -> "MyStruct"
>  pragma(msg, AliasStruct.Alias.stringof); // -> "MyStruct"
>  static assert(is(typeof(w.aliasStruct) == AliasStruct)); // -> true
>  static assert(is(typeof(w.aliasStruct).Alias == AliasStruct.Alias));
> // -> false
> }

Seems like a pb concerning whether Alias is a type or a symbol. See
A,B,C,D below:

void main()
{
 Wrapper w;

 pragma(msg, typeof(w.aliasStruct).Alias.stringof); // -> "MyStruct"
 pragma(msg, AliasStruct.Alias.stringof); // -> "MyStruct"
 static assert(is(typeof(w.aliasStruct) == AliasStruct)); // -> true
 static assert(is(w.aliasStruct.Alias == AliasStruct.Alias)); // -> true

 alias typeof(w.aliasStruct) A; // -> OK
 //alias typeof(w.aliasStruct).Alias B; // -> NOK
 //alias A.Alias C; // -> NOK
 alias w.aliasStruct.Alias D; // -> OK

 static assert(is(A.Alias == AliasStruct.Alias)); // -> true
 //static assert(is(B == AliasStruct.Alias));
 //static assert(is(C == AliasStruct.Alias));
 static assert(is(D == AliasStruct.Alias)); // -> true
}

I think A is enough for your need, but I don't get why B and C are not
accepted (DMD 2.059, Linux)