Fix: (link) Allow brackets in description

Org 9.3 stopped replacing brackets in link descriptions with braces
and started escaping them instead.

Fixes #283.  Thanks to Daniel Borchmann (@exot) for reporting.

README.org

@@ -560,6 +560,7 @@ Simple links may also be written manually in either sexp or non-sexp form, like:
 +  Command ~org-ql-sparse-tree~ accepts both string and sexp queries.  (Thanks to [[https://github.com/akirak][Akira Komamura]].)
 
 *Fixed*
++  Predicate ~link~ matches links whose descriptions contain escaped brackets (changed in Org 9.3).  (Thanks to [[https://github.com/exot][Daniel Borchmann]] for reporting.)
 +  Predicate ~src~'s matching of begin/end block lines, normalization of arguments, and handling in non-sexp queries.  (Thanks to [[https://github.com/akirak][Akira Komamura]] for reporting.)
 +  Predicate ~src~'s behavior with various arguments.
 +  Various compilation warnings.

org-ql.el

@@ -794,28 +794,33 @@ DESCRIPTION-OR-TARGET, match it in either description or target.
 If DESCRIPTION, match it in the description.  If TARGET, match it
 in the target.  If both DESCRIPTION and TARGET, match both,
 respectively."
+  ;; This `rx' part is borrowed from `org-make-link-regexps'.  It matches the interior of an
+  ;; Org link target (i.e. the parts between the brackets, including any escaped brackets).
+  (let ((link-target-part '(0+ (or (not (any "[]\\"))
+			           (and "\\" (0+ "\\\\") (any "[]"))
+			           (and (1+ "\\") (not (any "[]")))))))
     (cl-labels
         ((no-desc
           (match) (rx-to-string `(seq (or bol (1+ blank))
-                                    "[[" (0+ (not (any "]"))) (regexp ,match) (0+ (not (any "]")))
+                                      "[[" ,link-target-part (regexp ,match) ,link-target-part
                                       "]]")))
          (match-both
           (description target)
           (rx-to-string `(seq (or bol (1+ blank))
-                            "[[" (0+ (not (any "]"))) (regexp ,target) (0+ (not (any "]")))
+                              "[[" ,link-target-part (regexp ,target) ,link-target-part
-                            "][" (0+ (not (any "]"))) (regexp ,description) (0+ (not (any "]")))
+                              "][" (*? anything) (regexp ,description) (*? anything)
                               "]]")))
          ;; Note that these actually allow empty descriptions
          ;; or targets, depending on what they are matching.
          (match-desc
           (match) (rx-to-string `(seq (or bol (1+ blank))
-                                    "[[" (0+ (not (any "]")))
+                                      "[[" ,link-target-part
-                                    "][" (0+ (not (any "]"))) (regexp ,match) (0+ (not (any "]")))
+                                      "][" (*? anything) (regexp ,match) (*? anything)
                                       "]]")))
          (match-target
           (match) (rx-to-string `(seq (or bol (1+ blank))
-                                    "[[" (0+ (not (any "]"))) (regexp ,match) (0+ (not (any "]")))
+                                      "[[" ,link-target-part (regexp ,match) ,link-target-part
-                                    "][" (0+ (not (any "]")))
+                                      "][" (*? anything)
                                       "]]"))))
       (cond (description-or-target
              (rx-to-string `(or (regexp ,(no-desc description-or-target))
@@ -825,7 +830,7 @@ respectively."
              (match-both description target))
             (description (match-desc description))
             (target (rx-to-string `(or (regexp ,(no-desc target))
-                                     (regexp ,(match-target target))))))))
+                                       (regexp ,(match-target target)))))))))
 
 (defun org-ql--format-src-block-regexp (&optional lang)
   "Return regexp equivalent to `org-babel-src-block-regexp' with LANG filled in."
@@ -1563,12 +1568,8 @@ any link is found."
   ;; enabled nearly all of the time, in which case this function won't be called anyway, it's
   ;; probably not worth rewriting code all over the place to fix this.
   :preambles ((`(,predicate-names)
-               (list :regexp ;; Match a link with a target and optionally a description.
+               ;; Match a link with a target and optionally a description.
-                     (rx (or bol (1+ blank))
+               (list :regexp (org-ql--link-regexp :target ".*")))
-                         "[[" (1+ (not (any "]"))) "]"
-                         (optional (seq "[" (0+ (not (any "]"))) "]"))
-                         "]"
-                         (or eol blank))))
               (`(,predicate-names ,(and description-or-target
                                         (guard (not (keywordp description-or-target))))
                                   . ,plist)

org-ql.info

@@ -1055,6 +1055,9 @@ File: README.info,  Node: 07-pre,  Next: 063,  Up: Changelog
      (Thanks to Akira Komamura (https://github.com/akirak).)
 
    *Fixed*
+   • Predicate ‘link’ matches links whose descriptions contain escaped
+     brackets (changed in Org 9.3).  (Thanks to Daniel Borchmann
+     (https://github.com/exot) for reporting.)
    • Predicate ‘src’’s matching of begin/end block lines, normalization
      of arguments, and handling in non-sexp queries.  (Thanks to Akira
      Komamura (https://github.com/akirak) for reporting.)
@@ -1735,35 +1738,35 @@ Node: Links37255
 Node: Tips37942
 Node: Changelog38266
 Node: 07-pre39049
-Node: 06341784
+Node: 06341973
-Node: 06242319
+Node: 06242508
-Node: 06142624
+Node: 06142813
-Node: 0643192
+Node: 0643381
-Node: 05246246
+Node: 05246435
-Node: 05146546
+Node: 05146735
-Node: 0546969
+Node: 0547158
-Node: 04948498
+Node: 04948687
-Node: 04848778
+Node: 04848967
-Node: 04749127
+Node: 04749316
-Node: 04649536
+Node: 04649725
-Node: 04549944
+Node: 04550133
-Node: 04450305
+Node: 04450494
-Node: 04350664
+Node: 04350853
-Node: 04250867
+Node: 04251056
-Node: 04151028
+Node: 04151217
-Node: 0451275
+Node: 0451464
-Node: 03255376
+Node: 03255565
-Node: 03155779
+Node: 03155968
-Node: 0355976
+Node: 0356165
-Node: 02359276
+Node: 02359465
-Node: 02259510
+Node: 02259699
-Node: 02159790
+Node: 02159979
-Node: 0259995
+Node: 0260184
-Node: 0164073
+Node: 0164262
-Node: Notes64174
+Node: Notes64363
-Node: Comparison with Org Agenda searches64336
+Node: Comparison with Org Agenda searches64525
-Node: org-sidebar65225
+Node: org-sidebar65414
-Node: License65504
+Node: License65693
 
 End Tag Table
 

tests/data-links.org

@@ -0,0 +1,10 @@
+* Alpha
+
+Let us link to: [[id:74d357ac-fb9c-40d1-a63f-eca8a227321d][Bravo [a phrase in brackets]​]].
+
+* Bravo [a phrase in brackets]
+:PROPERTIES:
+:ID:       74d357ac-fb9c-40d1-a63f-eca8a227321d
+:END:
+
+* Charlie

tests/test-org-ql.el

@@ -1141,7 +1141,39 @@ with keyword arg NOW in PLIST."
           '("/r/emacs")))
       (org-ql-it "with :description and :target regexp"
         (org-ql-expect ('(link :description "em.cs" :target "em.cs" :regexp-p t))
-          '("/r/emacs"))))
+          '("/r/emacs")))
+
+      (describe "matches links whose descriptions contain brackets"
+        (before-each
+          (setq org-ql-test-buffer (org-ql-test-data-buffer "data-links.org")))
+
+        (org-ql-it "without arguments"
+          (org-ql-expect ('(link))
+            '("Alpha")))
+        (org-ql-it "with description-or-target"
+          (org-ql-expect ('(link "phrase"))
+            '("Alpha")))
+        (org-ql-it "with :description"
+          (org-ql-expect ('(link :description "phrase"))
+            '("Alpha")))
+        (org-ql-it "with :target"
+          (org-ql-expect ('(link :target "id:"))
+            '("Alpha")))
+        (org-ql-it "with :description and :target"
+          (org-ql-expect ('(link :description "phrase" :target "id"))
+            '("Alpha")))
+        (org-ql-it "with description-or-target regexp"
+          (org-ql-expect ('(link "id:.*" :regexp-p t))
+            '("Alpha")))
+        (org-ql-it "with :description regexp"
+          (org-ql-expect ('(link :description "phr.se" :regexp-p t))
+            '("Alpha")))
+        (org-ql-it "with :target regexp"
+          (org-ql-expect ('(link :target "id:.*" :regexp-p t))
+            '("Alpha")))
+        (org-ql-it "with :description and :target regexp"
+          (org-ql-expect ('(link :description "phr.se" :target "id:.*" :regexp-p t))
+            '("Alpha")))))
 
     (describe "(outline-path)"
       (org-ql-it "with one argument"