Re: RFC: color diagnostics markers

[Manuel López-Ibáñez <lopezibanez at gmail dot com>]

On 8 April 2013 16:43, Jakub Jelinek <jakub@redhat.com> wrote:
> On Mon, Apr 08, 2013 at 04:29:02PM +0200, Manuel López-Ibáñez wrote:
>> In fact, I would be fine with something like:
>>
>> pp_start_color()
>> pp_stop_color()
>> pp_wrap_in_color("")
>>
>> It is a bit more verbose, but also clearer when reading the code. And
>> no need for %[colorname] or %r or -Wformat support.
>
> But you then need to break the code into multiple function calls, which
> decreases readability.
>
>             pp_verbatim (context->printer,
>                          _("%s:%d:%d:   [ skipping %d instantiation contexts, "
>                            "use -ftemplate-backtrace-limit=0 to disable ]\n"),
>                          xloc.file, xloc.line, xloc.column, skip);

I guess "decreases readability" depends whether one knows what the
extra codes mean or not. I still have to check many times what %K and
%q#+T and other less common codes exactly do. I'd rather have less
codes than more.
And one could argue that the above call should be split, since the
"%s:%d:%d:" should not be translated.

That said, I would prefer that instead of

       expanded_location xloc;
        xloc = expand_location (loc);
          if (context->show_column)
            pp_verbatim (context->printer,
                         _("%r%s:%d:%d:%R  [ skipping %d instantiation
contexts, "
                           "use -ftemplate-backtrace-limit=0 to disable ]\n"),
                         "locus", xloc.file, xloc.line, xloc.column, skip);
          else
            pp_verbatim (context->printer,
                         _("%r%s:%d:%R   [ skipping %d instantiation contexts, "
                           "use -ftemplate-backtrace-limit=0 to disable ]\n"),
                         "locus", xloc.file, xloc.line, skip);

 we had:

             pp_verbatim (context->printer,
                          _("%X   [ skipping %d instantiation contexts, "
                            "use -ftemplate-backtrace-limit=0 to disable ]\n"),
                          expand_location(loc), skip);

and the pretty-printer takes care of applying color or not (or
expanding column numbers or not, etc).

Or without the extra %X code:

             pp_print_locus (context->printer, loc);
             pp_verbatim (context->printer,
                          _("  [ skipping %d instantiation contexts, "
                            "use -ftemplate-backtrace-limit=0 to
disable ]\n"), skip);

Or even if we don't want the pretty printer to know about ->show_column:

             diagnostic_print_locus (context, loc);
             pp_verbatim (context->printer,
                          _("  [ skipping %d instantiation contexts, "
                            "use -ftemplate-backtrace-limit=0 to
disable ]\n"), skip);

and the internal diagnostics machinery takes care of applying color or
not (or expanding column numbers or not, etc).

> can be right now a single call, while you would need several.  Also, if you
> eventually want to colorize something in say error_at, warning_at and
> similar format strings.  For those you really don't have the printer at

Do we really want to allow that much flexibility? Then the color_dict
needs to be dynamic or the caller is restricted to re-using existing
colornames.
I was expecting the use of color to be rather limited to a very very
few well-defined concepts. I was hoping that higher-level diagnostic
functions would be oblivious to the color stuff to not make the
diagnostics code much more complex.

Maybe I am wrong here and FE maintainers do want that flexibility.

Cheers,

Manuel.