Package: emacs;
Reported by: Philip Kaludercic <philipk <at> posteo.net>
Date: Sun, 30 Jan 2022 23:39:01 UTC
Severity: normal
Found in version 29.0.50
View this message in rfc822 format
From: Philip Kaludercic <philipk <at> posteo.net> To: Dmitry Gutov <dgutov <at> yandex.ru> Cc: Michael Albinus <michael.albinus <at> gmx.de>, 53644 <at> debbugs.gnu.org Subject: bug#53644: 29.0.50; xref-search-program breaks if programm not installed on a remote host Date: Tue, 08 Feb 2022 11:15:16 +0000
[Message part 1 (text/plain, inline)]
Dmitry Gutov <dgutov <at> yandex.ru> writes: > On 05.02.2022 16:38, Michael Albinus wrote: >> Dmitry Gutov <dgutov <at> yandex.ru> writes: >> >>> Hi Michael, >> Hi Dmitry, >> >>>>>> When invoking a command that respects xref-search-program via TRAMP, >>>>>> e.g. on a remote system that doesn't have (in my case ripgrep) >>>>>> installed, an error is signalled indicating that the search query >>>>>> couldn't be executed. >>>>> >>>>> One way to work around this will probably involve an addition to >>>>> find-file-hook and some code which checks (file-remote-p >>>>> buffer-file-name) and sets xref-search-program to a particular value >>>>> buffer-locally depending on the result. >>>>> >>>>> Or an around-advice for xref-matches-in-files. >>>> There are connection-local variables exactly for this use case. >>> >>> Is there a documented way on how to make the variable's value on >>> remote hosts customizable for the user too? >> Something like >> --8<---------------cut here---------------start------------->8--- >> (connection-local-set-profile-variables >> 'remote-xref-variables >> '((xref-search-program . "/bin/grep"))) >> (with-eval-after-load 'xref >> (connection-local-set-profiles >> '(:application tramp :machine "myhost") >> 'remote-xref-variables)) >> --8<---------------cut here---------------end--------------->8--- > > Nice. Some integration with the Customize UI probably wouldn't hurt, though. > > Philip, would you like to try writing a patch along the lines of > Michael's suggestion? > > It would need to use version checks, though, given that > connection-local vars were only added in Emacs 27. The following works, with one issue:
[Message part 2 (text/plain, inline)]
diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
index 6677b4f004..b2f82f1889 100644
--- a/lisp/progmodes/xref.el
+++ b/lisp/progmodes/xref.el
@@ -1751,15 +1751,7 @@ xref-matches-in-files
(remote-id (file-remote-p dir))
;; The 'auto' default would be fine too, but ripgrep can't handle
;; the options we pass in that case.
- (grep-highlight-matches nil)
- (command (grep-expand-template (cdr
- (or
- (assoc
- xref-search-program
- xref-search-program-alist)
- (user-error "Unknown search program `%s'"
- xref-search-program)))
- (xref--regexp-to-extended regexp))))
+ (grep-highlight-matches nil))
(when remote-id
(require 'tramp)
(setq files (mapcar
@@ -1770,25 +1762,56 @@ xref-matches-in-files
(when (file-name-quoted-p (car files))
(setq files (mapcar #'file-name-unquote files)))
(with-current-buffer output
- (erase-buffer)
(with-temp-buffer
(insert (mapconcat #'identity files "\0"))
- (setq default-directory dir)
- (setq status
- (xref--process-file-region (point-min)
- (point-max)
- shell-file-name
- output
- nil
- shell-command-switch
- command)))
- (goto-char (point-min))
- (when (and (/= (point-min) (point-max))
- (not (looking-at grep-re))
- ;; TODO: Show these matches as well somehow?
- (not (looking-at "Binary file .* matches")))
- (user-error "Search failed with status %d: %s" status
- (buffer-substring (point-min) (line-end-position))))
+ (let* ((default-directory dir)
+ (xref-search-program-alist xref-search-program-alist)
+ (program (if (version<= "27" emacs-version)
+ (with-connection-local-variables
+ xref-search-program)
+ xref-search-program)))
+ ;; In case `xref-search-program' is not installed on a
+ ;; remote system, we will speculatively try to start a
+ ;; different searcher to see if it is installed and works.
+ (catch 'ok
+ (while xref-search-program-alist
+ (with-current-buffer output
+ (erase-buffer))
+ (setq status
+ (xref--process-file-region
+ (point-min) (point-max)
+ shell-file-name
+ output nil shell-command-switch
+ (grep-expand-template
+ (or (alist-get program xref-search-program-alist)
+ (user-error "Unknown search program `%s'"
+ program))
+ (xref--regexp-to-extended regexp))))
+ (with-current-buffer output
+ (goto-char (point-min))
+ (unless (and (/= (point-min) (point-max))
+ (not (looking-at grep-re))
+ ;; TODO: Show these matches as well somehow?
+ (not (looking-at "Binary file .* matches")))
+ (when (and (not (eq program xref-search-program))
+ (version<= "27" emacs-version))
+ ;; If possible and necessary, save whatever program
+ ;; was found as a connection local variable.
+ (let* ((host (file-remote-p default-directory 'host))
+ (profile (intern (concat "xref-remote-" host))))
+ (connection-local-set-profile-variables
+ profile `((xref-search-program . ,program)))
+ (connection-local-set-profiles
+ (list :machine host) profile)))
+ (throw 'ok t)))
+ (setq xref-search-program-alist
+ (remq (assq program xref-search-program-alist)
+ xref-search-program-alist)
+ program (caar xref-search-program-alist)))
+ (with-current-buffer output
+ (user-error "Search failed with status %d: %s" status
+ (buffer-string)
+ (buffer-substring (point-min) (line-end-position)))))))
(while (re-search-forward grep-re nil t)
(push (list (string-to-number (match-string line-group))
(match-string file-group)
[Message part 3 (text/plain, inline)]
xref--process-file-region takes shell-file-name, that should depend on
the remote system. I could use something like
(with-parsed-tramp-file-name default-directory d
(tramp-get-method-parameter d 'tramp-remote-shell))
but it seems that `with-parsed-tramp-file-name' is not used outside of
tramp, and byte-compiling triggers a warning. Is there some better way
to do this?
> To get you started, here's one example of this feature's usage:
> https://github.com/company-mode/company-mode/blob/c25f1fbc3850e36e6521b77fa1641d5583365d8b/company-gtags.el#L71-L96
>
> And you can search in Emacs's own repository, of course, for other examples.
--
Philip Kaludercic
GNU bug tracking system
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1997,2003 nCipher Corporation Ltd,
1994-97 Ian Jackson.