Fix hangs caused by unbalanced braces in Python f-strings

* lisp/progmodes/python.el (python--font-lock-f-strings):
Temporarily bind forward-sexp-function to nil when calling
'up-list'.  (Bug#74738)

(cherry picked from commit 3c247f86b7639995c8ce2627049bcc91452d2cca)

diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index 477200b57207de10a89eb0c4d59c274b34519b39..47fb818c78e9b9c781edea9630343e805577775a 100644 (file)
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -617,7 +617,8 @@ the {...} holes that appear within f-strings."
               (forward-char 1)          ;Just skip over {{
             (let ((beg (match-beginning 0))
                   (end (condition-case nil
               (forward-char 1)          ;Just skip over {{
             (let ((beg (match-beginning 0))
                   (end (condition-case nil

-                           (let ((parse-sexp-ignore-comments))
+                           (let ((forward-sexp-function)
+                                 (parse-sexp-ignore-comments))

                              (up-list 1)
                              (min send (point)))
                          (scan-error send))))
                              (up-list 1)
                              (min send (point)))
                          (scan-error send))))