[Issue 752] Assertion failure: 'e->type->ty != Ttuple' on line 4518 in file 'mtype.c'

[BCS]

Walter Bright wrote:
> Sean Kelly wrote:
>> d-bugmail at puremagic.com wrote:
>>>
>>> ------- Comment #2 from bugzilla at digitalmars.com  2006-12-29 21:43 
>>> -------
>>> The statement:
>>>
>>>         mixin .Tuple!((TList[1 .. $]))
>>>
>>> is actually invalid, as it attempts to make a tuple of tuples. Instead,
>>>
>>>         mixin .Tuple!(TList[1 .. $])
>>>
>>> is correct.
>>
>> This seems a slim distinction.  Adding a set of parenthesis makes the 
>> code invalid?
> 
> Sure, in the same way that:
> 
>     int foo( (int, char) );
> 
> is not valid. Unless a compelling use case appears for the extra parens, 
> I'd prefer to disallow it.
> 

It would be vary handy to be able to make a member of a tuple be a tuple 
it's self. the perens might be a good way to denote this rather than the 
usual flattening.

It would allow a parser to convert a template parameter string to some 
sort of tuple structure. This would be vary useful for parsing things.

In fact, that was the first way I planed to do my "d sprit" implementation.

http://www.webpages.uidaho.edu/~shro8822/dsprit.d

After finding that this didn't work, I went with the "parse as you go" 
approach.