bug#23451: 25.0.93; Clarify the dependency on find/grep for platforms not having those tools

[Kaushal Modi <kaushal.modi@gmail.com>]

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From: kmodi@ulcf41.cld.analog.com (Kaushal.Modi)
To: bug-gnu-emacs@gnu.org
Subject:
--text follows this line--

The changes to the A/Q bindings in dired as discussed and confirmed are not
immediately compatible on Windows

Ref: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=23426#49

Even understanding that users would need to install GNU find & grep on
their Windows system to use the new implementations bound to A/Q in dired,
I believe that we should have the following:

- NOT bind A/Q at all if the right dependencies are not found. I tried the
A binding on Windows, it looked like it was grepping for the strings I
entered and returned an empty *xref* window. The same search on same files
worked as expected in RHEL (to be honest I love this new feature on RHEL,
and I might start using the A binding). Currently the implementation on
Windows gives an appearance that something was searched for and no results
were found. That is misleading!

Possible solution?

(when (correct-version-of-find-and-grep-found-p)
   (define-key dired-mode-map (kbd "A") #'dired-do-find-regexp)
   (define-key dired-mode-map (kbd "A") #'dired-do-find-regexp-and-replace))

- Another alternative would be (if we want to keep A/Q bindings) that a
user-error or error be thrown if the correct external dependencies are not
installed. The user should be let known that they need to install the GNU
find/grep executables for their platform in order to use those commands. In
the current implementation, the user will just assume that they searched
something and nothing got returned.

- The requirement to have find/grep installed should also go to backward
incompatible changes section in NEWS.

(I got an idea of "incompatible change" section in NEWS from this recent
commit:
http://git.savannah.gnu.org/cgit/emacs.git/commit/?h=emacs-25&id=c68a09107c1f7459c626d38be5e0e991912e57ec
 )

I would suggest that this bug be made blocking for the release of 25.1.

For Windows users, the bindings change for A/Q keys in dired is not
apparent to the user. At the very least, an error should be thrown if the
correct external dependencies (GNU version of find/grep) are not found on
the system PATH.



In GNU Emacs 25.0.93.4 (x86_64-unknown-linux-gnu, GTK+ Version 2.24.23)
 of 2016-05-04 built on ..
Repository revision: adc80b7e238e09b1b8c392ecf902d2b978d9016d
Windowing system distributor 'The X.Org Foundation', version 11.0.60900000
System Description: Red Hat Enterprise Linux Workstation release 6.6
(Santiago)

Configured using:
 'configure --with-modules
 --prefix=/home/kmodi/usr_local/apps/6/emacs/emacs-25
 'CPPFLAGS=-fgnu89-inline -I/home/kmodi/usr_local/6/include
 -I/usr/include/freetype2 -I/usr/include' 'CFLAGS=-ggdb3 -O0'
 'CXXFLAGS=-ggdb3 -O0' 'LDFLAGS=-L/home/kmodi/usr_local/6/lib
 -L/home/kmodi/usr_local/6/lib64 -ggdb3'
 PKG_CONFIG_PATH=/home/kmodi/usr_local/6/lib/pkgconfig:/home/kmodi/usr_local/6/lib64/pkgconfig:/cad/adi/apps/gnu/linux/x86_64/6/lib/pkgconfig:/cad/adi/apps/gnu/linux/x86_64/6/lib64/pkgconfig:/usr/lib/pkgconfig:/usr/lib64/pkgconfig:/usr/share/pkgconfig:/lib/pkgconfig:/lib64/pkgconfig'

Configured features:
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NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK2 X11 MODULES

Important settings:
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  value of $XMODIFIERS: @im=none
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
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Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Making completion list...

Load-path shadows:
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Features:
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Memory information:
((conses 16 87685 9438)
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-- 

-- 
Kaushal Modi

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