Subject: bug#62620: 30.0.50; Unused unwind-protect in verilog-mode

From: Basil Contovounesios <[email-masked]>
Date: Sun, 02 Apr 2023 17:39:47 +0100

Severity: minor
Tags: patch

As Mattias pointed out in https://bugs.gnu.org/62599#14, byte-compiling
verilog-mode currently emits the following warning:

  In verilog-diff-file-with-buffer:
  progmodes/verilog-mode.el:11894:26: Warning: ‘unwind-protect’ without unwind forms

The following patch tries to address that:

>From 619aad44b8877ff3e2def7cd42660f5c4fe0b5f3 Mon Sep 17 00:00:00 2001
From: "Basil L. Contovounesios" <[email-masked]>
Date: Sun, 2 Apr 2023 16:46:33 +0100
Subject: [PATCH] Fix verilog-diff-file-with-buffer

* lisp/progmodes/verilog-mode.el: Fix commentary to avoid implying
XEmacs defines diff-command.
(verilog-diff-file-with-buffer): Claim compatibility with Emacs 21
rather than XEmacs in commentary, since the latter does not seem to
define diff-command.  Use get-buffer in place of likely thinko
with-temp-buffer + BUFNAME + current-buffer.  Fix unused
unwind-protect: move temporary file deletion to its unwind forms.
Avoid race condition between file existence check and deletion.
Handle list-valued diff-switches.  Avoid passing empty argument to
diff-command.
---
 lisp/progmodes/verilog-mode.el | 54 ++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 25 deletions(-)

diff --git a/lisp/progmodes/verilog-mode.el b/lisp/progmodes/verilog-mode.el
index ac6fd382a46..9199119b602 100644
--- a/lisp/progmodes/verilog-mode.el
+++ b/lisp/progmodes/verilog-mode.el
@@ -356,7 +356,9 @@ verilog--suppressed-warnings
 (eval-and-compile
   ;; Both xemacs and emacs
   (condition-case nil
-      (require 'diff)  ; diff-command and diff-switches
+      ;; `diff-command' and `diff-switches',
+      ;; although XEmacs lacks the former.
+      (require 'diff)
     (error nil))
   (condition-case nil
       (require 'compile)  ; compilation-error-regexp-alist-alist
@@ -11883,31 +11885,33 @@ verilog-diff-file-with-buffer
 This requires the external program `diff-command' to be in your `exec-path',
 and uses `diff-switches' in which you may want to have \"-u\" flag.
 Ignores WHITESPACE if t, and writes output to stdout if SHOW."
-  ;; Similar to `diff-buffer-with-file' but works on XEmacs, and doesn't
-  ;; call `diff' as `diff' has different calling semantics on different
-  ;; versions of Emacs.
+  ;; Similar to `diff-buffer-with-file' but works on Emacs 21, and
+  ;; doesn't call `diff' as `diff' has different calling semantics on
+  ;; different versions of Emacs.
   (if (not (file-exists-p f1))
-      (message "Buffer `%s' has no associated file on disk" (buffer-name b2))
-    (with-temp-buffer "*Verilog-Diff*"
-                      (let ((outbuf (current-buffer))
-                            (f2 (make-temp-file "vm-diff-auto-")))
-                        (unwind-protect
-                            (progn
-                              (with-current-buffer b2
-                                (save-restriction
-                                  (widen)
-                                  (write-region (point-min) (point-max) f2 nil 'nomessage)))
-                              (call-process diff-command nil outbuf t
-                                            diff-switches  ; User may want -u in diff-switches
-                                            (if whitespace "-b" "")
-                                            f1 f2)
-                              ;; Print out results.  Alternatively we could have call-processed
-                              ;; ourself, but this way we can reuse diff switches
-                              (when show
-                                (with-current-buffer outbuf (message "%s" (buffer-string))))))
-                        (sit-for 0)
-                        (when (file-exists-p f2)
-                          (delete-file f2))))))
+      (message "Buffer `%s' has no associated file on disk" b2)
+    (let ((outbuf (get-buffer "*Verilog-Diff*"))
+          (f2 (make-temp-file "vm-diff-auto-")))
+      (unwind-protect
+          ;; User may want -u in `diff-switches'.
+          (let ((args `(,@(if (listp diff-switches)
+                              diff-switches
+                            (list diff-switches))
+                        ,@(and whitespace '("-b"))
+                        ,f1 ,f2)))
+            (with-current-buffer b2
+              (save-restriction
+                (widen)
+                (write-region (point-min) (point-max) f2 nil 'nomessage)))
+            (apply #'call-process diff-command nil outbuf t args)
+            ;; Print out results.  Alternatively we could have call-processed
+            ;; ourself, but this way we can reuse diff switches.
+            (when show
+              (with-current-buffer outbuf (message "%s" (buffer-string)))))
+        (sit-for 0)
+        (condition-case nil
+            (delete-file f2)
+          (error nil))))))
 
 (defun verilog-diff-report (b1 b2 diffpt)
   "Report differences detected with `verilog-diff-auto'.
-- 
2.34.1

Note that this function may have never worked in XEmacs, at least
judging from the diff.el in the following version I have locally:

  C-u M-x version
  XEmacs 21.4 (patch 24) "Standard C" [Lucid] (x86_64-linux-gnu, Mule)
  of Mon Jun 21 2021 on lgw01-amd64-053

It might be easy to avoid Emacs-isms in verilog-diff-file-with-buffer,
but considering verilog-diff-file-with-buffer probably never worked in
XEmacs, and XEmacs support is on its way out[0], I made no such changes.

[0]: https://github.com/veripool/verilog-mode/issues/1822#issuecomment-1422508926

Note also that verilog-diff-file-with-buffer until now called
with-temp-buffer with the name of a buffer previously created in
verilog-diff-auto.  I assume the intention was to instead call
with-current-buffer, so I made an analogous change.

The patch lists some further fixes.  WDYT?

Thanks,

-- 
Basil

In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.16.0, Xaw3d scroll bars) of 2023-04-02 built on blc
Repository revision: 97e35b149874a105a9975853a7fcd6f0034ddeab
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101003
System Description: Ubuntu 22.04.2 LTS

Configured using:
 'configure CC=gcc-12 'CFLAGS=-Og -ggdb3' --prefix=/home/blc/.local
 --with-file-notification=yes --with-x --with-x-toolkit=lucid
 PKG_CONFIG_PATH=/home/blc/.local/lib/pkgconfig:'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NOTIFY
INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11 XAW3D XDBE XIM XINPUT2 XPM
LUCID ZLIB

Important settings:
  value of $LC_MONETARY: en_IE.UTF-8
  value of $LC_NUMERIC: en_IE.UTF-8
  value of $LC_TIME: en_IE.UTF-8
  value of $LANG: en_GB.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-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

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny dired
dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg rfc6068
epg-config gnus-util text-property-search time-date subr-x mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
cl-loaddefs cl-lib sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils rmc iso-transl tooltip cconv eldoc paren electric
uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
term/x-win x-win term/common-win x-dnd 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 dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting cairo x-toolkit
xinput2 x multi-tty make-network-process emacs)

Memory information:
((conses 16 36607 9341)
 (symbols 48 5171 0)
 (strings 32 13873 1627)
 (string-bytes 1 377563)
 (vectors 16 9294)
 (vector-slots 8 148577 11610)
 (floats 8 23 25)
 (intervals 56 248 0)
 (buffers 984 10))