bug#50646: 28.0.50; narrow-to-defun sometimes narrows to wrong defun

[arthur . miller]

help-mode.el
Description: Text document

Bug No 1:

To reproduce this bug:

1. run Emacs -Q -l /path/to/attached/help-mode.el
2. type C-x f
3. in minibuffer type: when RET

The help-mode buffer that opens should show help for 'when' form, but it
shows the source code for the 'pop' macro which precedes the 'when' in
subr.el.

You can swtich to *Messages* buffer, I have output the position and
current-word at that position. Position is correct, it is the position
before opening parenthesis for '(defmacro when ...'. But current-word
shows 'x', which seems to be somethign from the pop macro that precedes
the 'when'. You can also clicn on "subr.el' in help-mode buffer and open
the source code, and then M-: (point) RET to confirm that the position
is correct.

The docs for 'narrow-to-defun' says the "current-defun" is one that
contains the point or follows the point. However, I am getting back the
one that precedes the point. Maybe it is bug elsewhere since
current-word also shows 'x', which I think is wrong, but maybe I am
wrong :).

I am not sure what is going on here, but there seems to be a bug
somewhere, in some rare case, and I think 'narrow-to-defun' is a good
place to start. I haven't found any other symbol but 'when' that results
in wrong form  narrowed, but maybe there is one.

Forward-char does not fix it, but forward-word seems to go far enough
into the enclosing 'when' form so that narrow-to-defun return correct
code.

I have another consideration here:

this is probably the same problem, but I am not sure. To reproduce,
follow step 1. and 2. from the prevous.

For the 3. type directory-files RET.

This should insert source code for directory-files from the dired.c. And
it does, but with a slight twist: it return just the body, not the
function declaration and the docs. I don't think it's a big deal, since
both are returned anyway, and I think I can fix it to return everything,
but as a note how it works. I am not sure if it's meant to work so or
not on c-sources. Notice also that the link to open the source file says
"C source code" not the name of the file, as it says for .el files. The
header is produced by 'help-function-def--button-function' which I have
adapted in 'help--function-source' (above help-make-xref) to return the
source code. I can send a patch to return the name of the file instead
of the string "C source code".




In GNU Emacs 28.0.50 (build 2, x86_64-pc-linux-gnu, cairo version 1.17.4)
 of 2021-09-15 built on pascal
Repository revision: b189b6f2564f903cf271a46910ad7a5df9da6918
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12013000
System Description: Arch Linux

Configured using:
 'configure --with-modules --with-cairo --without-compress-install
 --with-x-toolkit=no --with-gnutls --without-gconf --without-xwidgets
 --without-toolkit-scroll-bars --without-xaw3d --without-gsettings
 --with-mailutils --with-native-compilation 'CFLAGS=-O2 -march=native
 -mtune=native''

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM HARFBUZZ JPEG JSON LCMS2
LIBOTF LIBSYSTEMD LIBXML2 M17N_FLT MODULES NATIVE_COMP NOTIFY INOTIFY
OLDXMENU PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF X11 XDBE XIM XPM
ZLIB

Important settings:
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  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
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Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug comp comp-cstr warnings rx cl-extra
message rmc puny dired dired-loaddefs rfc822 mml mml-sec epa epg rfc6068
epg-config gnus-util rmail rmail-loaddefs auth-source cl-seq eieio
eieio-core cl-macs eieio-loaddefs password-cache json map
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make-network-process native-compile emacs)

Memory information:
((conses 16 90686 9107)
 (symbols 48 7862 1)
 (strings 32 21940 1868)
 (string-bytes 1 742230)
 (vectors 16 16860)
 (vector-slots 8 320588 16808)
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