foreach: compiler warning

[John Colvin]

On Tuesday, 30 July 2013 at 14:27:18 UTC, Chris wrote:
> I don't know if this has been raised before. I compiled an old 
> program which has a foreach loop like this:
>
> foreach(i; 0..10) {
>   if (condition) {
>     i--; // deprecated
>   }
> }
>
> dmd 2.063 compiled it without giving me any deprecation 
> warning, but the results were screwed up big time in the 
> program. The loop didn't work as expected. ldc2 gave me this 
> hint:
>
> Deprecation: variable modified in foreach body requires ref 
> storage class
>
> So I changed the loop to
>
> foreach(ref i; 0..10) {
>   if (condition) {
>     i--;
>   }
> }
>
> and it worked fine in both versions, dmd and ldc2. Mind you, 
> the ldc2 compiled version of the program worked correctly with 
> the deprecated code too. Only the dmd version didn't, although 
> it didn't complain at compile time.
>
> But maybe this is a well known issue, I haven't checked all 
> issues yet.

This has been discussed recently on the forums, can't remember 
where. The ldc hint is correct IIRC