From: Fabrice Nicol <fabrnicol@gmail.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 47408@debbugs.gnu.org
Subject: bug#47408: [PATCH] Etags support for Mercury -- fix explicit tags for existentially-quantified procedures
Date: Thu, 17 Jun 2021 13:19:26 +0200 [thread overview]
Message-ID: <CANTSrJuwZ0o4pRAeah+Ai7pdQrKU9Nk5uTcHEZVN6HWY5q2Ptw@mail.gmail.com> (raw)
In-Reply-To: <83y2b8zrxa.fsf@gnu.org>
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Hi Eli,
Thanks. I confirm that this works, but I have 2 follow-up issues with
> this patch:
>
> 1. It adds tags for some identifiers that AFAUI are actually
> keywords, and shouldn't be in the TAGS tables. Examples:
> "interface" (e.g., on line 146 of accumulator.m) and
> "implementation" (e.g., on line 166). I guess this is unintended?
> If so, how to fix it?
>
This is intended. I commented this in the commit message (one-word
declarations).
I confirm that
':- implementation' and ':-interface' are *formally* declarations in
Mercury as all others are.
They were not included in the previous version bercause of an incomplete
switch.
It is quite useful from a practical point of view to add them to the tag
base. When interfaces are big (they can reach a couple of thousand lines in
real-world programming) it is sometimes useful to have a bookmark to jump
to the start of the implementation section and back. I used to create an
ad-hoc emacs bookmark for this. Tagging removes the need for this. Simply
strike M-. at a blank line an select the interface/implementation tag.
In the C family this is the same as striking M-. on an header include
declaration and jumping to the header file and back. Some IDEs use F4 for
this. Think of Mercury interfaces as C headers.
>
>
> 2. It always produces "explicitly named" tags, which I think is
> unnecessary. AFAICT, this is related to the following snippet from
> mercury_pr:
>
> > + /* Left-trim type definitions. */
> > +
> > + while (pos > namelength + offset
> > + && c_isspace (s[pos - namelength - offset]))
> > + --offset;
> > +
> > + /* There is no need to correct namelength or call notinname. */
> > + s[pos - offset - 1] = '\0';
> > +
> > + make_tag (s + pos - namelength - offset, namelength, true, s,
> pos, lineno, linecharno);
> > + return pos;
>
> I don't understand why you need to overwrite s[pos - offset -1]
> with the null byte: the same effect could be obtained by adjusting
> the POS argument passed to make_tag. Also, you in effect chop off
> the last character of NAME, but don't adjust NAMELENGTH
> accordingly. These factors together cause make_tag to decide that
> an explicitly-named tag is in order, because name[namelength-1] is
> a null byte, which is rejected as being "not-a-name" character.
>
> To fix this second issue, I propose the change below, which should
> be applied on top of your patches:
>
> diff --git a/lib-src/etags.c b/lib-src/etags.c
> index 370e825..2b0288e 100644
> --- a/lib-src/etags.c
> +++ b/lib-src/etags.c
> @@ -6585,10 +6585,8 @@ mercury_pr (char *s, char *last, ptrdiff_t lastlen)
> && c_isspace (s[pos - namelength - offset]))
> --offset;
>
> - /* There is no need to correct namelength or call notinname. */
> - s[pos - offset - 1] = '\0';
> -
> - make_tag (s + pos - namelength - offset, namelength, true, s, pos,
> lineno, linecharno);
> + make_tag (s + pos - namelength - offset, namelength - 1, true,
> + s, pos - offset - 1, lineno, linecharno);
> return pos;
> }
>
> I've verified that etags after this change still produces the correct
> TAGS file, including for the file univ.m you sent up-thread.
>
> Do you agree with the changes I propose? If not, could you please
> explain what I miss here?
>
OK, this is another way of achieving an equivalent result. Please leave me
until tomorrow to perform more tests so that I can formally confirm that
this is fine.
Best
Fabrice
>
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next prev parent reply other threads:[~2021-06-17 11:19 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.12421.1623412982.2554.bug-gnu-emacs@gnu.org>
2021-06-14 15:10 ` bug#47408: [PATCH] Etags support for Mercury -- fix explicit tags for existentially-quantified procedures fabrice nicol
2021-06-14 16:04 ` Eli Zaretskii
2021-06-14 17:10 ` fabrice nicol
2021-06-14 17:42 ` Eli Zaretskii
2021-06-14 18:52 ` fabrice nicol
2021-06-17 10:50 ` Eli Zaretskii
2021-06-17 11:19 ` Fabrice Nicol [this message]
2021-06-17 11:42 ` Eli Zaretskii
2021-06-17 18:36 ` fabrice nicol
2021-06-18 11:29 ` Eli Zaretskii
2021-06-18 11:54 ` Francesco Potortì
2021-06-18 12:33 ` Eli Zaretskii
2021-06-18 13:53 ` fabrice nicol
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