[m-rev.] for post-commit review: improve documentation of query options

[Julien Fischer]

Hi Zoltan,

On Fri, 14 Jan 2022, Zoltan Somogyi wrote:

> Improve documention of the query options.
> 
> compiler/options.m:
> doc/user_guide.texi:
>     As above. Also, fix some existing inconsistencies between these two files.
> 
> 
> diff --git a/compiler/options.m b/compiler/options.m
> index c363d0f19..159c84c20 100644
> --- a/compiler/options.m
> +++ b/compiler/options.m
> @@ -4705,46 +4705,42 @@ options_help_output(Stream, !IO) :-
> 
> ...
>
>          "--output-libgrades",
> -        "\tPrint the list of compilation grades in which a library",
> -        "\tto be installed should be built to the standard output.",
> +        "\tPrint to standard output the list of compilation grades in which",
> +        "\tthe Mercury standard library is available with this compiler.",

The new description is not correct.  --output-libgrades prints the set
of library grades implied by the installed grades *and* any command line
options that affect the contents of that set (e.g --libgrades-exclude).
For example,

    $ mmc --no-libgrade --output-libgrades

  should, and does, print nothing.

--output-libgrades will only print the set of installed library grades in the
absence of any commmand line options that affect that set.

(We should consider adding a new option --output-installed-grades, which just
prints the installed stdlib grades ignoring any other options that
affects the library grade set.)

The rest looks fine.

Julien.