Should alias this support implicit construction in function calls and return statements?

[Simen Kjaeraas]

As discussed deep in the thread "Is there any reason why arithmetic  
operation
on shorts and bytes return int?"[1], D currently does not support this  
behavior:

struct bbyte {
     byte b;
     alias b this;
}

void foo(bbyte b) {}

void baz() {
     byte b;
     foo(b); // Cannot implicitly convert byte to bbyte.
}

bbyte baz( ) {
     byte b;
     return b; // Cannot implicitly convert byte to bbyte.
}

Kenji Hara points out, and I myself thought, that this was a deliberate  
design choice. Walter's post[2] in the aforementioned thread indicates  
(but does not make clear-cut) that he also thinks this implicit  
construction is desirable.

A previous discussion with Andrei[3] about implicit conversion of nameless  
tuples to named tuples resulted in a bug report[4], and it is clear that  
his view also supports some such form of implicit conversion.

A long time ago, when dinosaurs roamed the earth, walterandrei.pdf[5]  
suggested that opImplicitCastTo and opImplicitCastFrom take care of this  
conversion. Is anything like this still on the drawing board? Should alias  
this do it? How do we deal with cases were one field is alias this'd, and  
other fields are not?


[1]:  
http://forum.dlang.org/thread/mailman.2599.1355228650.5162.digitalmars-d@puremagic.com?page=3#post-mailman.2625.1355305365.5162.digitalmars-d:40puremagic.com

[2]:  
http://forum.dlang.org/thread/mailman.2599.1355228650.5162.digitalmars-d@puremagic.com?page=3#post-kaatc0:24hgn:242:40digitalmars.com

[3]:  
http://forum.dlang.org/thread/sedknwtlaefrxuflnbez@forum.dlang.org?page=8#postjul0qv:242l9d:241:40digitalmars.com

[4]: http://d.puremagic.com/issues/show_bug.cgi?id=8570

[5]: http://s3.amazonaws.com/dconf2007/WalterAndrei.pdf


-- 
Simen