Bring back foreach int indexes

[Steven Schveighoffer]

On Wednesday, 29 November 2023 at 16:56:54 UTC, deadalnix wrote:

>
> It cannot work in the general case, slice's size is a size_t .
>
> But if the compiler can prove it fits in 32bits, then there 
> should be no problem. VRP could do that.

VRP does not work here. The array comes from anywhere and can 
have any length. It needs to be validated (if you insist) at 
runtime.

But it's very very *VERY* uncommon to have an array with 2 
billion elements.

Note, this worked for years, pretty much without incident. I 
don't even remember why we removed it. It seems like one of those 
problems nobody had or was looking to solve. Yet, we solved it.

Actually, I just tested it out, and it gives a deprecation 
warning, but builds! This means it's actually quite easy to fix 
this, just remove the deprecation, and add the assert.

A great point from CyberShadow on the original PR that added the 
deprecation:

https://github.com/dlang/dmd/pull/8941#issuecomment-496306412

And note this was to "fix" an issue with foreach_reverse on int 
indexes, it was just snuck in there...

And here is another bug report that had a more detailed 
conversation (including from me): 
https://issues.dlang.org/show_bug.cgi?id=16149

-Steve