[m-rev.] for review: Print version information on two lines.

[Julien Fischer]

On Tue, 4 Mar 2014, Zoltan Somogyi wrote:

> On Tue, 4 Mar 2014 14:08:43 +1100, Peter Wang <novalazy at gmail.com> wrote:
>> On the other hand, it is kind of nice for all the pertinent information
>> to be on the first line.  There may be scripts which already expect it.
>> I don't know if they exist and you could argue they shouldn't do that,
>> but if someone else changed *their* output for a trivial reason and
>> broke *my* script, I'd be pretty annoyed.
>
> I don't know of any such scripts, and I don't think you do either,
> since ...
>
>> If we're going to change the output then perhaps it would be better to
>> just drop the word "configured"?
>
> ... that change could break any such scripts too.
>
> I am with Julien on this one.

I think you meant Paul -- I haven't said anything (yet) ;-)

> We shouldn't break existing applications
> if we don't have to, but this does change does not do that. And if any
> scripts DO break, their writers shouldn't be surprised, since they
> depended on something they shouldn't have.

The version message has had its current form for *many* years.  Yes,
people pobably shouldn't write scripts that rely on that form, but
it's (currently) the most convenient way of extracting certain
information about a Mercury installation.  (Another way would be
to read the contents of the Mercury.options file but that's less
stable than the version message.)

One improvement that should be made here is to add the following
options to the compiler:

    --output-short-version
    --output-host-arch
    --output-target-arch

Cheers,
Julien.