bug#10033: 24.0.91; Uncommenting fails in Autoconf mode

bug#10033: 24.0.91; Uncommenting fails in Autoconf mode

[Chong Yidong]

With latest trunk:

emacs -Q configure.ac
M-;
asdf
C-SPC M-<
M-x uncomment-region RET

The uncomment-region does nothing; the line containing "dnl asdf"
remains commented out.

This is a regression; in Emacs 23.3, uncomment-region works as expected.
However, using the version of autoconf.el from Emacs 23 in Emacs 24
still shows the problem.

In GNU Emacs 24.0.91.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.2.0)
 of 2011-11-13 on furball
Windowing system distributor `The X.Org Foundation', version 11.0.11004000
configured using `configure  '--with-x-toolkit=gtk3' 'CFLAGS=-g''

bug#10033: 24.0.91; Uncommenting fails in Autoconf mode

[Chong Yidong]

Chong Yidong <cyd@gnu.org> writes:

> With latest trunk:
>
> emacs -Q configure.ac
> M-;
> asdf
> C-SPC M-<
> M-x uncomment-region RET
>
> The uncomment-region does nothing; the line containing "dnl asdf"
> remains commented out.

This is because the value of comment-start-skip in Autoconf mode is

   "\\(?:\\<dnl\\|#\\) +"

The \< is intended to avoid matching a "dnl" that is part of a word.  In
Emacs 23, the \< matches the beginning of the line

dnl asdf

in Autoconf mode.  But in Emacs 24, it does not match the beginning of
that line at all.  I don't see any related regexp changes in NEWS.  Does
it ring a bell for anyone?

bug#10033: 24.0.91; Uncommenting fails in Autoconf mode

[Andreas Schwab]

Chong Yidong <cyd@gnu.org> writes:

> This is because the value of comment-start-skip in Autoconf mode is
>
>    "\\(?:\\<dnl\\|#\\) +"
>
> The \< is intended to avoid matching a "dnl" that is part of a word.

dnl isn't a word, it is a comment, so \< cannot match it.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

bug#10033: 24.0.91; Uncommenting fails in Autoconf mode

[Chong Yidong]

Andreas Schwab <schwab@linux-m68k.org> writes:

> Chong Yidong <cyd@gnu.org> writes:
>
>> This is because the value of comment-start-skip in Autoconf mode is
>>
>>    "\\(?:\\<dnl\\|#\\) +"
>>
>> The \< is intended to avoid matching a "dnl" that is part of a word.
>
> dnl isn't a word, it is a comment, so \< cannot match it.

Yet syntax-propertize-function for Autoconf uses

  (set (make-local-variable 'syntax-propertize-function)
       (syntax-propertize-rules ("\\<dnl\\>" (0 "<"))))

which does work for matching only occurrences of `dnl' as separate
tokens.

bug#10033: 24.0.91; Uncommenting fails in Autoconf mode

[Andreas Schwab]

Chong Yidong <cyd@gnu.org> writes:

> Yet syntax-propertize-function for Autoconf uses
>
>   (set (make-local-variable 'syntax-propertize-function)
>        (syntax-propertize-rules ("\\<dnl\\>" (0 "<"))))
>
> which does work for matching only occurrences of `dnl' as separate
> tokens.

That's before dnl turns into a comment.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."