Fix: (heading) Don't match strings as regexps

Reported-by: Alex Popescu <https://github.com/al3xandru>

README.org

@@ -555,7 +555,8 @@ Simple links may also be written manually in either sexp or non-sexp form, like:
 
 ** 0.8.5-pre
 
-Nothing new yet.
+*Fixes*
++ Predicate ~heading~ incorrectly matched strings as regular expressions, sometimes returning incorrect results.  (See [[https://github.com/alphapapa/org-ql/discussions/410][discussion]].  Thanks to [[https://github.com/al3xandru][Alex Popescu]] for reporting.)
 
 ** 0.8.4
 

org-ql.el

@@ -1461,40 +1461,16 @@ Org effort string, like \"5\" or \"0:05\"."
                (list :regexp (rx bol (0+ space) ":STYLE:" (1+ space) "habit" (0+ space) eol))))
   :body (org-is-habit-p))
 
-(org-ql-defpred (heading h) (&rest strings)
+(org-ql-defpred (heading h) (&rest _strings)
   "Return non-nil if current entry's heading matches all STRINGS.
 Matching is done case-insensitively."
   :coalesce t
   :normalizers ((`(,predicate-names . ,args)
-                 ;; "h" alias.
-                 `(heading ,@args)))
-  ;; TODO: Adjust regexp to avoid matching in tag list.
-  :preambles ((`(,predicate-names)
-               ;; This clause protects against the case in which the
-               ;; arguments are nil, which would cause an error in
-               ;; `rx-to-string' in other clauses.  This can happen
-               ;; with `org-ql-completing-read', e.g. when the input
-               ;; is "h:" while the user is typing.
-               (list :regexp (rx bol (1+ "*") (1+ blank) (0+ nonl))
-                     :case-fold t :query query))
-              (`(,predicate-names ,string)
-               ;; Only one string: match with preamble, then let predicate confirm (because
-               ;; the match could be in e.g. the tags rather than the heading text).
-               (list :regexp (rx-to-string `(seq bol (1+ "*") (1+ blank) (0+ nonl)
-                                                 ,string)
-                                           'no-group)
-                     :case-fold t :query query))
-              (`(,predicate-names . ,strings)
-               ;; Multiple strings: use preamble to match against first
-               ;; string, then let the predicate match the rest.
-               (list :regexp (rx-to-string `(seq bol (1+ "*") (1+ blank) (0+ nonl)
-                                                 ,(car strings))
-                                           'no-group)
-                     :case-fold t :query query)))
-  ;; TODO: In Org 9.2+, `org-get-heading' takes 2 more arguments.
-  :body (let ((heading (org-get-heading 'no-tags 'no-todo))
-              (case-fold-search t))
-          (--all? (string-match it heading) strings)))
+                 ;; NOTE: Each string argument must be converted to a regexp
+                 ;; for testing by the body, so we just normalize to the
+                 ;; `heading-regexp' predicate, leaving this predicate as
+                 ;; one that merely regexp-quotes its arguments.
+                 `(heading-regexp ,@(mapcar #'regexp-quote args)))))
 
 (org-ql-defpred (heading-regexp h*) (&rest regexps)
   "Return non-nil if current entry's heading matches all REGEXPS (regexp strings).

org-ql.info

@@ -1076,7 +1076,12 @@ File: README.info,  Node: 085-pre,  Next: 084,  Up: Changelog
 5.1 0.8.5-pre
 =============
 
-Nothing new yet.
+*Fixes*
+   • Predicate ‘heading’ incorrectly matched strings as regular
+     expressions, sometimes returning incorrect results.  (See
+     discussion (https://github.com/alphapapa/org-ql/discussions/410).
+     Thanks to Alex Popescu (https://github.com/al3xandru) for
+     reporting.)
 
 
 File: README.info,  Node: 084,  Next: 083,  Prev: 085-pre,  Up: Changelog
@@ -1979,45 +1984,45 @@ Node: Links38883
 Node: Tips39570
 Node: Changelog39894
 Node: 085-pre40788
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-Node: Comparison with Org Agenda searches73350
-Node: org-sidebar74239
-Node: License74518
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+Node: Comparison with Org Agenda searches73625
+Node: org-sidebar74514
+Node: License74793
 
 End Tag Table
 

tests/test-org-ql.el

@@ -218,7 +218,8 @@ with keyword arg NOW in PLIST."
       (it "coalesces a single AND clause that uses two predicates (and preserves predicate order)"
         (expect (org-ql--normalize-query '(and (rifle "foo") (rifle "bar")
                                                (heading "baz") (heading "buz")))
-                :to-equal '(and (rifle :regexps '("foo" "bar")) (heading "baz" "buz"))))
+                ;; NOTE: `heading' is normalized to `heading-regexp'.
+                :to-equal '(and (rifle :regexps '("foo" "bar")) (heading-regexp "baz" "buz"))))
       (it "preserves independent OR clauses"
         (expect (org-ql--normalize-query '(and (or (rifle "foo") (rifle "bar"))
                                                (or (rifle "baz") (rifle "buz"))))
@@ -1112,7 +1113,12 @@ with keyword arg NOW in PLIST."
           '("Take over the world")))
       (org-ql-it "with two arguments"
         (org-ql-expect ('(heading "Take over" "world"))
-          '("Take over the world"))))
+          '("Take over the world")))
+      (org-ql-it "does not match strings as regexps"
+        (org-ql-expect ('(heading "over"))
+          '("Take over the universe" "Take over the world" "Take over Mars" "Take over the moon"))
+        (org-ql-expect ('(heading "[over]"))
+          nil)))
 
     (describe "(heading-regexp)"
       (org-ql-it "with one argument"