Re: [RFA] Add inclusive range support for Rust

[Joel Brobecker <brobecker@adacore.com>]

Hi Tom,

>  /* In an OP_RANGE expression, either bound could be empty, indicating
>     that its value is by default that of the corresponding bound of the
> -   array or string.  So we have four sorts of subrange.  This
> -   enumeration type is to identify this.  */
> -   
> +   array or string.  Also, the upper end of the range can be exclusive
> +   or inclusive.  So we have six sorts of subrange.  This enumeration
> +   type is to identify this.  */
> +
>  enum range_type
>    {
>      BOTH_BOUND_DEFAULT,		/* "(:)"  */
>      LOW_BOUND_DEFAULT,		/* "(:high)"  */
>      HIGH_BOUND_DEFAULT,		/* "(low:)"  */
> -    NONE_BOUND_DEFAULT		/* "(low:high)"  */
> +    NONE_BOUND_DEFAULT,		/* "(low:high)"  */
> +    NONE_BOUND_DEFAULT_INCLUSIVE, /* Rust "low..=high"  */
> +    LOW_BOUND_DEFAULT_INCLUSIVE, /* Rust "..=high"  */
>    };

Where the bounds exclusive before? The comments and the samples
of code I have been finding seem to indicate that the bounds
were already considered inclusive. But I can see how this is
not all that clear.

Perhaps one way to clarify that is to use language-agnostic mathematical
notations for the ranges? Eg, using square brackets such as "[1:3[" or
perhaps "[1:3)" as I have sometimes seen?

I'll continue with the rest of the patch in the meantime...

-- 
Joel