Fix query-replace-regexp undo feature

Ensure that non-regexp strings used with `looking-at' are quoted.
* lisp/replace.el (perform-replace): Quote regexp (Bug#37073).
* test/lisp/replace-tests.el (replace-tests-perform-replace-regexp-flag):
New variable.
(replace-tests-with-undo): Use it.
(query-replace-undo-bug37073): Add tests.

2 files changed, 30 insertions, 3 deletions

diff --git a/lisp/replace.el b/lisp/replace.el
index 08feb8eae7e..0ddebb12704 100644
--- a/lisp/replace.el
+++ b/lisp/replace.el
@@ -2614,7 +2614,8 @@ It must return a string."
                                    (setq real-match-data
                                          (save-excursion
                                            (goto-char (match-beginning 0))
-                                           (looking-at search-string)
+                                           ;; We must quote the string (Bug#37073)
+                                           (looking-at (regexp-quote search-string))
                                            (match-data t (nth 2 elt)))
                                          noedit
                                          (replace-match-maybe-edit
@@ -2624,7 +2625,9 @@ It must return a string."
                                          real-match-data
                                          (save-excursion
                                            (goto-char (match-beginning 0))
-                                           (looking-at next-replacement)
+                                           (if regexp-flag
+                                               (looking-at next-replacement)
+                                             (looking-at (regexp-quote next-replacement)))
                                            (match-data t (nth 2 elt))))
                                    ;; Set replaced nil to keep in loop
                                    (when (eq def 'undo-all)
diff --git a/test/lisp/replace-tests.el b/test/lisp/replace-tests.el
index cd30633e377..cd08a522e39 100644
--- a/test/lisp/replace-tests.el
+++ b/test/lisp/replace-tests.el
@@ -365,6 +365,9 @@ Each element has the format:
 (defvar replace-tests-bind-read-string nil
   "A string to bind `read-string' and avoid the prompt.")
 
+(defvar replace-tests-perform-replace-regexp-flag t
+  "Value for regexp-flag argument passed to `perform-replace' in undo tests.")
+
 (defmacro replace-tests-with-undo (input from to char-nums def-chr &rest body)
   "Helper to test `query-replace' undo feature.
 INPUT is a string to insert in a temporary buffer.
@@ -412,7 +415,7 @@ Return the last evalled form in BODY."
                     (if replace-tests-bind-read-string
                         (lambda (&rest args) replace-tests-bind-read-string)
                       (symbol-function 'read-string))))
-           (perform-replace ,from ,to t t nil))
+           (perform-replace ,from ,to t replace-tests-perform-replace-regexp-flag nil))
          ,@body))))
 
 (defun replace-tests--query-replace-undo (&optional comma)
@@ -454,5 +457,26 @@ Return the last evalled form in BODY."
       input "a" "B" ((?\s . (1 2 3)) (?E . (4)) (?U . (5))) ?q
       (string= input (buffer-string))))))
 
+(ert-deftest query-replace-undo-bug37073 ()
+  "Test for https://debbugs.gnu.org/37073 ."
+  (let ((input "theorem 1\ntheorem 2\ntheorem 3"))
+    (should
+     (replace-tests-with-undo
+         input "theorem \\([0-9]+\\)"
+         "theorem \\\\ref{theo_\\1}"
+         ((?\s . (1 2)) (?U . (3)))
+         ?q
+       (string= input (buffer-string)))))
+  ;; Now run a test with regexp-flag arg in `perform-replace' set to nil
+  (let ((input " ^theorem$ 1\n ^theorem$ 2\n ^theorem$ 3")
+        (replace-tests-perform-replace-regexp-flag nil)
+        (expected " theo 1\n ^theorem$ 2\n ^theorem$ 3"))
+    (should
+     (replace-tests-with-undo
+         input "^theorem$"
+         "theo"
+         ((?\s . (1 2 4)) (?U . (3)))
+         ?q
+       (string= expected (buffer-string))))))
 
 ;;; replace-tests.el ends here