[m-rev.] for review: make binary_{input, output}_stream_offset abort on overflow

[Zoltan Somogyi]

On Mon, 14 Oct 2019 17:09:51 +1100 (AEDT), Julien Fischer <jfischer at opturion.com> wrote:
> Make binary_{input,output}_stream_offset abort on overflow.
> 
> Make binary{input,output}_stream_offset abort with an exception if the offset
> they return cannot be respresented using Mercury's int type.  The current
> impelmentation just silently casts the offset to an int.

Fix spelling of implementation.

>       % Returns the offset (in bytes) into the specified binary output stream.
> +    % Throws an exception if the offset is outside the range that can be
> +    % represented by the int type; the 64-bit version below should be used in
> +    % that case.

In that sentence, "that case" seems to refer to "when this throws an exception".
I would suggest "To avoid this possibility, you can use the 64-bit offset version
of this predicate below", for both predicates.

> +    ( if int64.to_int(Offset64, OffsetPrime) then
> +        Offset = OffsetPrime
> +    else
> +        error("io.binary_input_stream_offset: offset exceeds range of an int")
> +    ).

I think we should use error($pred, "...")  wherever possible.

Apart from that, the diff is fine.

Zoltan.