bug#36317: [PATCH] Correct the name part of defun-prompt-regex in sh-script-mode

[Ola Nilsson]

POSIX.1-2017 defines that functions should have a name that
'consisting solely of underscores, digits, and alphabetics from the
portable character set'.  Make sure the name part of
defun-prompt-regexp starts with a letter and allows underscores.

* lisp/progmodes/sh-script.el (defun-prompt-regexp):
Correct the function name part of the regexp.
---
 lisp/progmodes/sh-script.el | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lisp/progmodes/sh-script.el b/lisp/progmodes/sh-script.el
index 853a3500ee..24f242572f 100644
--- a/lisp/progmodes/sh-script.el
+++ b/lisp/progmodes/sh-script.el
@@ -1619,9 +1619,9 @@ sh-mode
   (setq-local defun-prompt-regexp
               (concat
                "^\\("
-               "\\(function[ \t]\\)?[ \t]*[[:alnum:]]+[ \t]*([ \t]*)"
+               "\\(function[ \t]\\)?[ \t]*[[:alpha:]][[:alnum:]_]+[ \t]*([ 
\t]*)"
                "\\|"
-               "function[ \t]+[[:alnum:]]+[ \t]*\\(([ \t]*)\\)?"
+               "function[ \t]+[[:alpha:]][[:alnum:]_]+[ \t]*\\(([ \t]*)\\)?"
                "\\)[ \t]*"))
   (setq-local add-log-current-defun-function #'sh-current-defun-name)
   (add-hook 'completion-at-point-functions
-- 
2.11.0