to auto or not to auto ( in foreach )

[Lobelia Noakes via Digitalmars-d-learn]

On Wednesday, 20 July 2016 at 15:40:16 UTC, Lobelia Noakes wrote:
> On Sunday, 17 July 2016 at 01:58:59 UTC, pineapple wrote:
>> On Sunday, 17 July 2016 at 01:57:21 UTC, pineapple wrote:
>>> On Saturday, 16 July 2016 at 22:05:49 UTC, ketmar wrote:
>>>> actually, `foreach (v; rng)` looks like `foreach` is 
>>>> *reusing* *existing* *variable*. most of the time you can 
>>>> put `immutable` or something like that there to note that it 
>>>> is not reusing (purely cosmetical thing), but sometimes you 
>>>> cannot, and then `auto` is perfect candidate... but it is 
>>>> not allowed. (sigh)
>>>
>>> Chipping in my agreement. foreach(x; y) makes as much 
>>> syntactic sense as for(x = 0; x < y; x++) where x was not 
>>> previously defined. One does not expect something that does 
>>> not look like every other variable definition in the language 
>>> to be defining a new variable.
>>
>> Furthermore, if foreach(int x; y) is legal then why isn't 
>> foreach(auto x; y)?
>
> By the way there's an error in the grammar:
>
> ForeachTypeAttribute:
>     ref
>     TypeCtor
>
> But BasicType also already includes TypeCtor. So a TypeCtor in 
> a foreach typelist is ? well hard to say, part of basic type or 
> part of ForeachTypeAttribute ?

It's a minor issue BTW. I think that everybody that would write a 
D parser will skip parsing of TypeCtor in ForeachTypeAttribute 
and rather consider them as part of the type. I'm not sure if it 
can be completly removed from ForeachTypeAttribute...Does anyone 
know ?