Re: [C--] qc-- fails to compile switch statement

Norman Ramsey wrote:
>  > If a front-ends knows some values in this set of unused range values is
>  > infeasible, then it can list only the feasible unused range values for the
>  > default. This might result in more efficient translation.
>
> If a front end knows some values are infeasible, they should be listed
> on the switch statement as a whole, *not* on the default case.
>
>  > But I believe in most cases front-ends cannot derive which values are
>  > infeasible at runtime, so (*) will provide a convenience to front-end
>  > writers as they only need to assert the range limits of switch statement
>  > expressions.
>
> We've added convenience features to C-- in the past, but only under
> where the cost/benefit ratio overwhelmingly favorable.  That's why we
> abandoned declaration before us, and that's why we believe the span
> mechanism should be improved.  But the benefit of making switch
> statements more convenient is not worth the cost.
I want to say the design of C-- is nearly perfect for my purpose.  
Improved span is certainly a great thing.
However, features like default case and bool registers are small but 
have more exposures to the beginning users of C--.
>   The language
> manual is already too large and too difficult to understand.
>   
My experience is that the manual is very well written and easy to 
understand. The difficulty of adopting C-- as a back end is not because 
of the documentation, but because of lacking some convenient high level 
constructs. Great efforts are needed to compile high-level constructs to 
C-- constructs, sometimes the efforts are no less than just generating 
assembly code.

Luckily, these low-level constructs are exactly what I want,
Ning
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