bug#38658: perl-mode: EOF in same color as here doc text

bug#38658: perl-mode: EOF in same color as here doc text

[積丹尼 Dan Jacobson]

$ nl e.pl
     1  print <<EOF;
     2  bla
     3  EOF
$ emacs e.pl

Why is line 1 in color A, and lines 2 and 3 in color B?
How about instead lines 1 and 3 in color A, and line 2 in color B?
emacs-version "26.3"

bug#38658: perl-mode: EOF in same color as here doc text

[Lars Ingebrigtsen]

積丹尼 Dan Jacobson <jidanni@jidanni.org> writes:

> $ nl e.pl
>      1  print <<EOF;
>      2  bla
>      3  EOF
> $ emacs e.pl
>
> Why is line 1 in color A, and lines 2 and 3 in color B?
> How about instead lines 1 and 3 in color A, and line 2 in color B?

This is apparently due to the following code:

(defun perl-syntax-propertize-special-constructs (limit)
[...]
      ;; A Here document.
      (let ((names (cdr (get-text-property (nth 8 state) 'syntax-table))))
        (when (cdr names)
          (setq names (reverse names))
          ;; Multiple heredocs on a single line, we have to search from the
          ;; beginning, since we don't know which names might be
          ;; before point.
          (goto-char (nth 8 state)))
        (while (and names
                    (re-search-forward
                     (pcase-let ((`(,name . ,indented) (pop names)))
                       (concat "^" (if indented "[ \t]*")
                               (regexp-quote name) "\n"))
                     limit 'move))
          (unless names
            (put-text-property (1- (point)) (point) 'syntax-table
                               (string-to-syntax "> c"))))))

We apparently want to put that syntax on at the end of the heredoc, but
stop fontifying at the start of the final EOF.  I poked around a bit in
the code to see whether I could make it do that, and...  I can't.

So I'm Cc-ing Stefan, who wrote this.  :-)

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#38658: perl-mode: EOF in same color as here doc text

[Stefan Monnier]

First, I'll note that all the rest of font-lock highlights the comment
and string delimiters the same as the comment and string contents,
except for the `font-lock-comment-delimiter-face`, so you might like to
check how `font-lock-comment-delimiter-face` is done.

> We apparently want to put that syntax on at the end of the heredoc, but
> stop fontifying at the start of the final EOF.

Rather than "not fontify" the delimiter, I think it'll be much easier to
add extra fontification to it.


        Stefan

bug#38658: perl-mode: EOF in same color as here doc text

[Lars Ingebrigtsen]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

> First, I'll note that all the rest of font-lock highlights the comment
> and string delimiters the same as the comment and string contents,
> except for the `font-lock-comment-delimiter-face`, so you might like to
> check how `font-lock-comment-delimiter-face` is done.

Hm, right...

I just noticed that heredocs in .sh files are fontified identically to
in Perl-mode, by the way.

>> We apparently want to put that syntax on at the end of the heredoc, but
>> stop fontifying at the start of the final EOF.
>
> Rather than "not fontify" the delimiter, I think it'll be much easier to
> add extra fontification to it.

Right.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no