bug#64140: 29.0.91; C-u M-x grep doesn't work correctly after M-x vc-git-grep

bug#64140: 29.0.91; C-u M-x grep doesn't work correctly after M-x vc-git-grep

[Daniel Martín via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Steps to reproduce:

emacs -Q
C-x C-f emacs/src/xdisp.c RET
M-x vc-git-grep RET
Perform any search.
Place the point over any symbol, for example, char_can_wrap_before.
C-u M-x grep

The suggested grep command to confirm is

git --no-pager char_can_wrap_before *.c

which is incorrect, it should be

grep --color=auto -nH --null -e char_can_wrap_before *.c

If I run a regular grep with M-x grep, then C-u M-x now suggests the
correct grep command.

In GNU Emacs 29.0.91 (build 8, aarch64-apple-darwin21.6.0, NS
 appkit-2113.60 Version 12.6 (Build 21G115)) of 2023-06-07 built on
 Daniels-MacBook-Pro.local
Repository revision: bcc222251e1a750a11e365f2faa641cc56c1169d
Repository branch: emacs-29
Windowing system distributor 'Apple', version 10.3.2113
System Description:  macOS 12.6

Configured using:
 'configure 'CFLAGS=-O0 -g3 -fsanitize=address'
 CPPFLAGS=-I/opt/homebrew/opt/openjdk@11/include'

Configured features:
ACL GNUTLS JSON LCMS2 LIBXML2 MODULES NOTIFY KQUEUE NS PDUMPER PNG
SQLITE3 THREADS TOOLKIT_SCROLL_BARS WEBP ZLIB

Important settings:
  value of $LC_CTYPE: UTF-8
  locale-coding-system: utf-8-unix

Major mode: C++//l

Minor modes in effect:
  shell-dirtrack-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  abbrev-mode: t

Load-path shadows:
None found.

Features:
(pcvs pcvs-defs vc-cvs vc-rcs pcvs-parse pcvs-info ewoc make-mode
pcmpl-gnu autoconf autoconf-mode pcmpl-unix ruby-mode novice org-attach
perl-mode completion dos-w32 find-cmd rng-xsd xsd-regexp rng-cmpct
rng-nxml rng-valid rng-loc rng-uri rng-parse nxml-parse rng-match rng-dt
rng-util rng-pttrn nxml-ns nxml-mode nxml-outln nxml-rap nxml-util
nxml-enc xmltok cc-langs pcase emacs-news-mode emoji-labels emoji
multisession sqlite transient edmacro kmacro org-element org-persist
org-id org-refile avl-tree oc-basic ol-eww ol-rmail ol-mhe ol-irc
ol-info ol-gnus nnselect gnus-art mm-uu mml2015 mm-view mml-smime smime
dig gnus-sum gnus-group gnus-undo gnus-start gnus-dbus dbus gnus-cloud
nnimap nnmail mail-source utf7 nnoo gnus-spec gnus-int gnus-range
gnus-win ol-docview ol-bibtex bibtex ol-bbdb ol-w3m ol-doi org-link-doi
org ob ob-tangle ob-ref ob-lob ob-table ob-exp org-macro org-src
ob-comint org-pcomplete org-list org-footnote org-faces org-entities
ob-emacs-lisp ob-core ob-eval org-cycle org-table ol org-fold
org-fold-core org-keys oc org-loaddefs cal-menu calendar cal-loaddefs
org-version org-compat org-macs korea-util timezone parse-time iso8601
mhtml-mode css-mode js c-ts-common sgml-mode facemenu textsec
uni-scripts idna-mapping uni-confusable textsec-check gnutls
network-stream url-http url-gw nsm url-cache url-auth format-spec eww
xdg url-queue shr pixel-fill kinsoku url-file svg xml dom browse-url url
url-proxy url-privacy url-expand url-methods url-history url-cookie
generate-lisp-file url-domsuf url-util mm-url gnus nnheader range
cus-edit cus-start cus-load view disp-table whitespace shadow mail-extr
emacsbug message yank-media puny rfc822 mml mml-sec epa derived epg
rfc6068 epg-config gnus-util mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils texinfo texinfo-loaddefs tabify
man imenu apropos mule-diag debug backtrace arc-mode archive-mode
doc-view filenotify jka-compr image-mode exif cl-print shortdoc
info-look noutline outline icons emacs-authors-mode reposition pulse
color semantic/symref/grep semantic/symref semantic/util-modes
semantic/util semantic semantic/tag semantic/lex semantic/fw mode-local
find-func cedet etags fileloop generator xref project smerge-mode diff
grep compile text-property-search add-log log-view pcvs-util mailcap
help-fns radix-tree cl-extra pp wid-edit descr-text help-mode dabbrev
ffap thingatpt url-parse auth-source eieio eieio-core cl-macs
password-cache json map url-vars misearch multi-isearch sort files-x
shell pcomplete comint ansi-osc ansi-color ring find-dired ediff
ediff-merg ediff-mult ediff-wind ediff-diff ediff-help ediff-init
ediff-util vc bug-reference byte-opt gv bytecomp byte-compile cc-mode
cc-fonts cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars
cc-defs info vc-git diff-mode easy-mmode vc-dispatcher sh-script rx smie
treesit cl-seq executable dired-aux dired dired-loaddefs time-date
subr-x cl-loaddefs cl-lib rmc iso-transl tooltip cconv eldoc paren
electric uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
term/ns-win ns-win ucs-normalize mule-util term/common-win tool-bar dnd
fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode lisp-mode prog-mode register page tab-bar menu-bar rfn-eshadow
isearch easymenu timer select scroll-bar mouse jit-lock font-lock syntax
font-core term/tty-colors frame minibuffer nadvice seq simple cl-generic
indonesian philippine cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek
romanian slovak czech european ethiopic indian cyrillic chinese
composite emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help abbrev obarray oclosure cl-preloaded button loaddefs
theme-loaddefs faces cus-face macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget keymap
hashtable-print-readable backquote threads kqueue cocoa ns lcms2
multi-tty make-network-process emacs)

Memory information:
((conses 16 1463351 251576)
 (symbols 48 56078 46)
 (strings 32 340855 23457)
 (string-bytes 1 12808718)
 (vectors 16 90277)
 (vector-slots 8 2453536 236046)
 (floats 8 536 683)
 (intervals 56 177206 7850)
 (buffers 976 217))

bug#64140: 29.0.91; C-u M-x grep doesn't work correctly after M-x vc-git-grep

[Eli Zaretskii]

> Date: Sun, 18 Jun 2023 02:32:28 +0200
> From:  Daniel Martín via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Steps to reproduce:
> 
> emacs -Q
> C-x C-f emacs/src/xdisp.c RET
> M-x vc-git-grep RET
> Perform any search.
> Place the point over any symbol, for example, char_can_wrap_before.
> C-u M-x grep
> 
> The suggested grep command to confirm is
> 
> git --no-pager char_can_wrap_before *.c
> 
> which is incorrect, it should be
> 
> grep --color=auto -nH --null -e char_can_wrap_before *.c

You are saying that vc-git-grep should use a separate history
variable?

bug#64140: 29.0.91; C-u M-x grep doesn't work correctly after M-x vc-git-grep

[Daniel Martín via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Sun, 18 Jun 2023 02:32:28 +0200
>> From:  Daniel Martín via "Bug reports for GNU Emacs,
>>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>> 
>> Steps to reproduce:
>> 
>> emacs -Q
>> C-x C-f emacs/src/xdisp.c RET
>> M-x vc-git-grep RET
>> Perform any search.
>> Place the point over any symbol, for example, char_can_wrap_before.
>> C-u M-x grep
>> 
>> The suggested grep command to confirm is
>> 
>> git --no-pager char_can_wrap_before *.c
>> 
>> which is incorrect, it should be
>> 
>> grep --color=auto -nH --null -e char_can_wrap_before *.c
>
> You are saying that vc-git-grep should use a separate history
> variable?

Yes, that's one possible solution, but it's probably too late to change
that.  Perhaps there should be a configuration option in the vc package
so users can choose to have a separate history variable for git grep.

grep-default-command already tries to extract different parts of the
command using regular expressions.  We could adapt grep-default-command
so that it handles git grep well, but I don't think that'd be a very
clean or future-proof solution.