D 2.0 - dalegates to function

[Frits van Bommel]

Reiner Pope wrote:
> sergk wrote:
>> Perhaps it's time to to bump an old request postponed to 2.0 times =)
>>
>> So, how about to add some thunking magic - how  complex/complicated to 
>> implement it?
>>
> This works, except for the inout issue as Frits mentioned:
> 
>> T delegate(U) thunkify(T, U...)(T function(U) f)
>> {
>>     struct Foo
>>     {
>>         T function(U) _f;
>>         T run(U u) { return _f(u); }
>>     }
>>     Foo* value = new Foo;
>>     value._f = f;
>>     return &value.run;
>> }

Your version re-pushes arguments. Also, I'm pretty sure it doesn't 
handle varargs.

I'd also like to note that my version for this (delegate that calls a 
function) should be implementable right now, without re-pushing 
arguments and with vararg support (I think). The only case it _doesn't_ 
handle is if the last parameter is out/inout, and would otherwise not be 
passed in EAX. So it only breaks if a 3-byte struct or anything larger 
than 4 bytes is passed as the last parameter and that parameter is out 
or inout.
That is, aside from the fact it only supports DMD's extern(D) functions.