bug#74934: 30.0.92; Unexpected behavior by which-function-mode in erc-mode buffers

bug#74934: 30.0.92; Unexpected behavior by which-function-mode in erc-mode buffers

[Anush V]

Hello Maintainers,

I guess this is probably unexpected behavior by which-function-mode in erc-mode
buffers and so reporting this.


steps to reproduce:
emacs --no-init
M-x erc
;; join some channel.
M-x which-function-mode

Current behavior:
In erc buffers, which-function-mode displays either "[n/a]" or a string based on
the chat history in the mode line.

Expected behavior:
which-function-mode shouldn’t be adding any string to mode line in erc buffers


Thank you for your time!

* * *

In GNU Emacs 30.0.92 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.41, cairo
version 1.18.0)
Windowing system distributor 'The X.Org Foundation', version 11.0.12101014
System Description: Guix System

Configured using:
 'configure
 CONFIG_SHELL=/gnu/store/3jhfhxdf6v5ms10x5zmnl166dh3yhbr1-bash-minimal-5.1.16/bin/bash
 SHELL=/gnu/store/3jhfhxdf6v5ms10x5zmnl166dh3yhbr1-bash-minimal-5.1.16/bin/bash --prefix=/gnu/store/dgpfiflaxb8j33jcbqk29wadcykajl51-emacs-next-30.0.92-0.881d593 --enable-fast-install --with-cairo --with-modules --with-native-compilation=aot --disable-build-details'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG LCMS2
LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NATIVE_COMP NOTIFY INOTIFY
PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS
TREE_SITTER X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB

--
Regards,
Anush V

bug#74934: 30.0.92; Unexpected behavior by which-function-mode in erc-mode buffers

[J.P.]

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Hi Anush,

Appreciate you reporting this.

Anush V <j@gnu.org> writes:

> steps to reproduce:
> emacs --no-init
> M-x erc
> ;; join some channel.
> M-x which-function-mode
>
> Current behavior:
> In erc buffers, which-function-mode displays either "[n/a]" or a string based on
> the chat history in the mode line.

FTR, I'm able to reproduce it.

> Expected behavior:
> which-function-mode shouldn’t be adding any string to mode line in erc buffers

The first of the attached patches should hopefully address the issue.

Thanks,
J.P.


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From 76eab2b23f46c885051f2bcb985ab15c3e851033 Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <jp@neverwas.me>
Date: Tue, 17 Dec 2024 17:53:34 -0800
Subject: [PATCH 1/2] [5.6.1] Disable which-func-mode in erc-imenu buffers

* lisp/erc/erc-imenu.el (erc-imenu-setup): Move after module definition
so the variable `erc-imenu-mode' is defined.  Run teardown code when
module is deactivated.  Set `which-func-mode' to nil locally.
(erc-imenu-mode, erc-imenu-enable, erc-imenu-disable): Manage membership
of `erc-imenu--disable-which-func' in `which-function-mode-hook'.
(erc-imenu--disable-which-func): New function.  (Bug#74934)
---
 lisp/erc/erc-imenu.el | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/lisp/erc/erc-imenu.el b/lisp/erc/erc-imenu.el
index 4c9cbfc1580..68c7895e2dd 100644
--- a/lisp/erc/erc-imenu.el
+++ b/lisp/erc/erc-imenu.el
@@ -132,23 +132,36 @@ erc-create-imenu-index
 (defvar-local erc-imenu--create-index-function nil
   "Previous local value of `imenu-create-index-function', if any.")
 
-(defun erc-imenu-setup ()
-  "Wire up support for Imenu in an ERC buffer."
-  (when (and (local-variable-p 'imenu-create-index-function)
-             imenu-create-index-function)
-    (setq erc-imenu--create-index-function imenu-create-index-function))
-  (setq imenu-create-index-function #'erc-create-imenu-index))
-
 ;;;###autoload(autoload 'erc-imenu-mode "erc-imenu" nil t)
 (define-erc-module imenu nil
   "Simple Imenu integration for ERC."
   ((add-hook 'erc-mode-hook #'erc-imenu-setup)
+   (add-hook 'which-function-mode-hook #'erc-imenu--disable-which-func)
    (unless erc--updating-modules-p (erc-buffer-do #'erc-imenu-setup)))
   ((remove-hook 'erc-mode-hook #'erc-imenu-setup)
-   (erc-with-all-buffers-of-server nil nil
-     (when erc-imenu--create-index-function
-       (setq imenu-create-index-function erc-imenu--create-index-function)
-       (kill-local-variable 'erc-imenu--create-index-function)))))
+   (remove-hook 'which-function-mode-hook #'erc-imenu--disable-which-func)
+   (erc-buffer-do #'erc-imenu-setup)))
+
+(defun erc-imenu-setup ()
+  "Set up or tear down Imenu integration."
+  (if erc-imenu-mode
+      (progn
+        (when (and (local-variable-p 'imenu-create-index-function)
+                   imenu-create-index-function)
+          (setq erc-imenu--create-index-function imenu-create-index-function))
+        (setq imenu-create-index-function #'erc-create-imenu-index)
+        (when (boundp 'which-func-mode)
+          (setq which-func-mode nil)))
+    (when erc-imenu--create-index-function
+      (setq imenu-create-index-function erc-imenu--create-index-function))
+    (kill-local-variable 'erc-imenu--create-index-function)
+    (kill-local-variable 'which-func-mode)))
+
+(defun erc-imenu--disable-which-func ()
+  "Silence `which-function-mode' in ERC buffers."
+  (defvar which-func-mode)
+  (erc-with-all-buffers-of-server nil nil
+    (setq which-func-mode nil)))
 
 (provide 'erc-imenu)
 
-- 
2.47.1


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From 6b331f127a7c4f1c4085521ea74c68f644f93cce Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <jp@neverwas.me>
Date: Mon, 22 Apr 2024 18:11:24 -0700
Subject: [PATCH 2/2] [5.6.1] Add lisp-imenu-generic-expression for ERC hacking

* lisp/erc/erc-backend.el (define-erc-response-handler): Add
`doc-string' to `declare' specification.
* lisp/erc/erc-imenu.el (erc-imenu-add-devel-patterns(): Add locally
autoloaded function for defining `imenu' patterns when hacking on ERC.
---
 lisp/erc/erc-backend.el |  1 +
 lisp/erc/erc-imenu.el   | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/lisp/erc/erc-backend.el b/lisp/erc/erc-backend.el
index e72fa036f17..311e3a624e6 100644
--- a/lisp/erc/erc-backend.el
+++ b/lisp/erc/erc-backend.el
@@ -1662,6 +1662,7 @@ define-erc-response-handler
                                   ([&or integerp symbolp]
                                    &rest [&or integerp symbolp])]
                            &optional sexp sexp def-body))
+           (doc-string 2)
            (indent defun))
   (if (numberp name) (setq name (intern (format "%03i" name))))
   (setq aliases (mapcar (lambda (a)
diff --git a/lisp/erc/erc-imenu.el b/lisp/erc/erc-imenu.el
index 68c7895e2dd..c6cb5655e2d 100644
--- a/lisp/erc/erc-imenu.el
+++ b/lisp/erc/erc-imenu.el
@@ -163,6 +163,29 @@ erc-imenu--disable-which-func
   (erc-with-all-buffers-of-server nil nil
     (setq which-func-mode nil)))
 
+;;;###autoload
+(defun erc-imenu-add-devel-patterns ()
+  "Tell `imenu' about ERC-defined macros."
+  ;; This currently produces results like "ERC response FOO BAR".  I'd
+  ;; obviously be nicer to end up with "erc-response-FOO" and
+  ;; "erc-response-BAR", possibly as separate items.  Likewise for
+  ;; modules: "erc-foo-mode" instead of "ERC module foo".
+  (cl-pushnew `("ERC response"
+                ,(rx bol (* (syntax whitespace))
+                     "(define-erc-response-handler (" (group (+ nonl)) ")")
+                1)
+              lisp-imenu-generic-expression
+              :test #'equal)
+  (cl-pushnew `("ERC module"
+                ,(rx bol (* (syntax whitespace))
+                     ;; Lisp-mode-symbol.
+                     "(define-erc-module " (group (+ (| (syntax word)
+                                                        (syntax symbol)
+                                                        (: "\\" nonl)))))
+                1)
+              lisp-imenu-generic-expression
+              :test #'equal))
+
 (provide 'erc-imenu)
 
 ;;; erc-imenu.el ends here
-- 
2.47.1

bug#74934: 30.0.92; Unexpected behavior by which-function-mode in erc-mode buffers

[Eli Zaretskii]

> Cc: emacs-erc@gnu.org, 74934@debbugs.gnu.org
> From: "J.P." <jp@neverwas.me>
> Date: Tue, 17 Dec 2024 18:24:02 -0800
> 
> > steps to reproduce:
> > emacs --no-init
> > M-x erc
> > ;; join some channel.
> > M-x which-function-mode
> >
> > Current behavior:
> > In erc buffers, which-function-mode displays either "[n/a]" or a string based on
> > the chat history in the mode line.
> 
> FTR, I'm able to reproduce it.
> 
> > Expected behavior:
> > which-function-mode shouldn’t be adding any string to mode line in erc buffers
> 
> The first of the attached patches should hopefully address the issue.

Is this for the release branch?  That is, is this a recent regression?

And if so, what is the second patch for?

Thanks.

bug#74934: 30.0.92; Unexpected behavior by which-function-mode in erc-mode buffers

[J.P.]

Eli Zaretskii <eliz@gnu.org> writes:

>> Cc: emacs-erc@gnu.org, 74934@debbugs.gnu.org
>> From: "J.P." <jp@neverwas.me>
>> Date: Tue, 17 Dec 2024 18:24:02 -0800
>> 
>> > steps to reproduce:
>> > emacs --no-init
>> > M-x erc
>> > ;; join some channel.
>> > M-x which-function-mode
>> >
>> > Current behavior:
>> > In erc buffers, which-function-mode displays either "[n/a]" or a string based on
>> > the chat history in the mode line.
>> 
>> FTR, I'm able to reproduce it.
>> 
>> > Expected behavior:
>> > which-function-mode shouldn’t be adding any string to mode line in erc buffers
>> 
>> The first of the attached patches should hopefully address the issue.
>
> Is this for the release branch?  That is, is this a recent regression?

No, this is for Emacs master (and ERC 5.6.1). AFAICT, the bug has been
with us since at least Emacs 26.3, although "[n/a]" used to be "[???]".

>
> And if so, what is the second patch for?

For anyone wondering, the second patch is for contributors working on
ERC (I will add a news item). If you load ERC and invoke the function
`erc-imenu-add-devel-patterns' in your config, your next visit to
erc-backend.el should allow you to see something like

  ERC response 311 314
  ERC response 312
  ERC response 313
  ERC response 315 318 323 369
  ERC response 317
  ERC response 319
  ERC response 311

after typing

  M-x imenu <RET> 31 <TAB>

(whereas before you'd see nothing). Hitting RET on the first candidate
should take you to

  (define-erc-response-handler (311 314)
    "WHOIS/WHOWAS notices." nil ...)

As mentioned in the comment, I'd much rather it generate something like

  erc-server-311
  erc-server-314
  ...
  erc-server-311

but I don't know how to do that or if it's even possible. (If anyone out
there has any clues, please share. TIA.)