Propertize only perl prototype chars `][$%&*;+@\' as punctuation

This prevents variables in signatures such as `sub add ($a, $b)' from
being treated as punctuation.
* lisp/progmodes/perl-mode.el (perl-syntax-propertize-function):
Strictly match only prototype characters as punctuation.  (Bug#26037)

Copyright-paperwork-exempt: yes

1 files changed, 5 insertions, 3 deletions

diff --git a/lisp/progmodes/perl-mode.el b/lisp/progmodes/perl-mode.el
index a516f07e72f..b75f32ee200 100644
--- a/lisp/progmodes/perl-mode.el
+++ b/lisp/progmodes/perl-mode.el
@@ -255,9 +255,11 @@
       ;; format statements
       ("^[ \t]*format.*=[ \t]*\\(\n\\)"
        (1 (prog1 "\"" (perl-syntax-propertize-special-constructs end))))
-      ;; Funny things in `sub' arg-specs like `sub myfun ($)' or `sub ($)'.
-      ;; Be careful not to match "sub { (...) ... }".
-      ("\\<sub\\(?:[\s\t\n]+\\(?:\\sw\\|\\s_\\)+\\)?[\s\t\n]*(\\([^)]+\\))"
+      ;; Propertize perl prototype chars `$%&*;+@\[]' as punctuation
+      ;; in `sub' arg-specs like `sub myfun ($)' and `sub ($)'.  But
+      ;; don't match subroutine signatures like `sub add ($a, $b)', or
+      ;; anonymous subs like "sub { (...) ... }".
+      ("\\<sub\\(?:[\s\t\n]+\\(?:\\sw\\|\\s_\\)+\\)?[\s\t\n]*(\\([][$%&*;+@\\]+\\))"
        (1 "."))
       ;; Turn __DATA__ trailer into a comment.
       ("^\\(_\\)_\\(?:DATA\\|END\\)__[ \t]*\\(?:\\(\n\\)#.-\\*-.*perl.*-\\*-\\|\n.*\\)"