Subject: 27.0.50; Emacs-Lisp and ElDoc confusion with some strings

From: Mauro Aranda <[email-masked]>
Date: Sat, 4 May 2019 18:14:54 -0300

Hello.

I've found some cases where ElDoc displays function information in
the echo area, when it shouldn't.

Try the following, with the attached test.el (no need to eval it):
1) emacs -Q
2) C-x C-f test.el
3) There are two 'and' in the doc string of foo.  Do a search for 'and'
and stop after the first:
C-s and C-f: ElDoc doesn't show a function in the echo area, that's
fine.
Now search for the next 'and':
C-s C-s C-f: ElDoc shows `and: (CONDITIONS...)' in the echo area.  That
shouldn't happen.
4) Also, there's a " in a comment, in the last line.  Search for "here",
just like for "and" before:
C-s here C-f: ElDoc again shows `and: (CONDITIONS...)'.  That again,
shouldn't happen.

In these cases, I see that elisp--fnsym-in-current-sexp doesn't return nil,
as it should when point is inside a string.  So far, I've only found that
a quoted ( confuses it, when the ) is not quoted.  But for the bug to
become visible, the word that follows ")" has to be an interned symbol.

Another example is in the file lisp/files.el.  Put point in the doc string
of
the variable file-name-version-regexp, and see that ElDoc shows
`while: (TEST BODY...)' in the echo area.  I think that happens because
there are " in some comments lines before the doc string.

It seems that the problem is that elisp--beginning-of-sexp calls
forward-sexp, even though its doc string explicitly says that it assumes
point is not in a string or a comment.  Most of the time it still works,
but it fails in some cases, and in those cases, the check for the current
word not being inside a string loses its purpose.

Perhaps using the return value of syntax-ppss before calling
elisp--beginning-of-sexp would be enough to avoid this confusion.

Also, let me ask: was there any discussion about the usefulness of having
ElDoc display information when point is inside a comment?  I ask because
I only see the intention to check when not inside a string.

Best regards,
Mauro.

In GNU Emacs 27.0.50 (build 1, i686-pc-linux-gnu, GTK+ Version 3.18.9)
 of 2019-05-04 built on the-blackbeard
Repository revision: a90ad2297391cf5fe284a4c6e81724360ed018a4
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
System Description: Ubuntu 16.04.6 LTS

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

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