bug#49906: perl-mode: variables that conflict with keywords aren't fontified properly

[Tomasz Konojacki <me@xenu.pl>]

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On Sat, 07 Aug 2021 11:10:43 +0200
Lars Ingebrigtsen <larsi@gnus.org> wrote:

> You can concatenate any number of lists with append, so I don't quite
> understand what you mean here.

You're right, I was confused. I was under the wrong impression that
append takes only two arguments. It was probably caused by the combination
of reading a tutorial[1] instead of the real documentation and
struggling with unrelated syntax errors. Obviously, I'm an elisp
beginner.

A revised patch is attached.

[1] - https://www.gnu.org/software/emacs/manual/html_node/eintr/append.html

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From 79e3adb5d2958fbe76a5f03e6fd8fa9e78cb8a42 Mon Sep 17 00:00:00 2001
From: Tomasz Konojacki <me@xenu.pl>
Date: Sat, 7 Aug 2021 11:23:37 +0200
Subject: [PATCH] perl-mode: fix variable fontification

* lisp/progmodes/perl-mode.el: handle variables first to avoid
conflicting with keywords. This fixes cases like "$package".
(bug#49906)
---
 lisp/progmodes/perl-mode.el | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/lisp/progmodes/perl-mode.el b/lisp/progmodes/perl-mode.el
index f49ee4cb2b..4e14c30bc5 100644
--- a/lisp/progmodes/perl-mode.el
+++ b/lisp/progmodes/perl-mode.el
@@ -178,6 +178,14 @@
 
 (defconst perl-font-lock-keywords-2
   (append
+   '(;; Fontify function, variable and file name references. They have to be
+     ;; handled first because they might conflict with keywords.
+     ("&\\(\\sw+\\(::\\sw+\\)*\\)" 1 font-lock-function-name-face)
+     ;; Additionally fontify non-scalar variables.  `perl-non-scalar-variable'
+     ;; will underline them by default.
+     ("[$*]{?\\(\\sw+\\(::\\sw+\\)*\\)" 1 font-lock-variable-name-face)
+     ("\\([@%]\\|\\$#\\)\\(\\sw+\\(::\\sw+\\)*\\)"
+      (2 'perl-non-scalar-variable)))
    perl-font-lock-keywords-1
    `( ;; Fontify keywords, except those fontified otherwise.
      ,(concat "\\<"
@@ -188,15 +196,6 @@
      ;;
      ;; Fontify declarators and prefixes as types.
      ("\\<\\(has\\|local\\|my\\|our\\|state\\)\\>" . font-lock-keyword-face) ; declarators
-          ;;
-     ;; Fontify function, variable and file name references.
-     ("&\\(\\sw+\\(::\\sw+\\)*\\)" 1 font-lock-function-name-face)
-     ;; Additionally fontify non-scalar variables.  `perl-non-scalar-variable'
-     ;; will underline them by default.
-     ;;'("[$@%*][#{]?\\(\\sw+\\)" 1 font-lock-variable-name-face)
-     ("[$*]{?\\(\\sw+\\(::\\sw+\\)*\\)" 1 font-lock-variable-name-face)
-     ("\\([@%]\\|\\$#\\)\\(\\sw+\\(::\\sw+\\)*\\)"
-      (2 'perl-non-scalar-variable))
      ("<\\(\\sw+\\)>" 1 font-lock-constant-face)
      ;;
      ;; Fontify keywords with/and labels as we do in `c++-font-lock-keywords'.
-- 
2.27.0.windows.1