Subject: Re: [bug#35790] [PATCH] scripts: lint: Handle warnings with a record type.

From: Ludovic Courtès <[email-masked]>
Date: Tue, 21 May 2019 16:41:53 +0200

Hello!

Christopher Baines <[email-masked]> skribis:

> Rather than emiting warnings directly to a port, have the checkers return the
> warning or warnings.
>
> This makes it easier to use the warnings in different ways, for example,
> loading the data in to a database, as you can work with the <lint-warning>
> records directly, rather than having to parse the output to determine the
> package and location.

Yay!

> +            <lint-warning>

As a rule of thumb, it’s best to not export the record type descriptor
(RTD) because then anything could happen.  In this case, I think the
tests would be just as readable if we used ‘lint-warning-message’ &
co. instead of matching on the record.

WDYT?

> +(define* (make-warning package message
> +                       #:key field location)
> +  (make-lint-warning
> +   package
> +   message

In practice MESSAGE is already translated.  I think it would be more
flexible if it were not; ‘lint-warning-message’ would always return the
English message, and it’d be up to the user to call ‘gettext’ on it,
like we do for package descriptions.

To achieve this, you’d need a little trick so that ‘xgettext’ can still
extract the messages, like:

  (define-syntax-rule make-warning
    (syntax-rule (G_)
      ((_ package (G_ message) rest ...)
       (%make-warning package message rest ...))))

where ‘%make-warning’ is the procedure you define above.

Then you need an explicit call to ‘G_’ at the point where messages are
displayed.

Does that make sense?

> +(define (append-warnings . args)
> +  (fold (lambda (arg warnings)
> +          (cond
> +           ((list? arg)
> +            (append warnings
> +                    (filter lint-warning?
> +                            arg)))
> +           ((lint-warning? arg)
> +            (append warnings
> +                    (list arg)))
> +           (else warnings)))
> +        '()
> +        args))

I always feel that we should have procedures that operate on lists of
anything, like ‘append’, and thus ‘append-warnings’ looks like an
anti-pattern to me.

What about simply ensuring that every checker returns a list of
<lint-warning>s?  That way, we wouldn’t have to do such things, I think.

That’s all!

Thanks,
Ludo’.