[Issue 11070] Allow declaration statement in a switch expression

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http://d.puremagic.com/issues/show_bug.cgi?id=11070



--- Comment #5 from monarchdodra at gmail.com 2013-09-20 00:53:31 PDT ---
(In reply to comment #3)
> Well, not just auto, you just want to be able to make a declaration inside the
> switch expression. This would also apply to a while statement too.
> 
> In C++, this is legal:
> 
> //----
>     while (int i = 1)
>     {}
> 
>     switch (int i = 1)
>     {}
> //----
> 
> This is a very reduced use case, but I've seen cases where it is useful.
> 
> The D grammar does not allow it though. I don't see why not though.

To answer my own self:

>     while (int i = 1)
>     {}

This would probably be illegal in D anyways, since we aren't allowed
assignments in if/for/while. Arguably, it's not an "assignment" but a
"declaration", so it shouldn't be a problem either. Still, it's a thin line,
and I have (albeit very rarely) also made that "typo", when copy pasting code.

>     switch (int i = 1)
>     {}

Switch is special, because it doesn't actually test the args, so I see better
chances of this being made legal.

IMO, while the use cases arn't very important, not supporting this for switch
would just be a gratuitous deviation from C++ (IMO). Then again, C doesn't
support it either (afaik), so...

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