Fix markdown-wiki-link-p overriding match data issue

CHANGES.md

@@ -39,6 +39,7 @@
     -   Fix too indended list face issue [GH-569][]
     -   Fix creating imenu index issue when there is no level-1 header too[GH-571][]
     -   Fix highlighting consecutive HTML comments[GH-584][]
+    -   Fix `markdown-follow-thing-at-point` failing on subdir search [GH-590][]
 
   [gh-290]: https://github.com/jrblevin/markdown-mode/issues/290
   [gh-311]: https://github.com/jrblevin/markdown-mode/issues/311
@@ -62,6 +63,7 @@
   [gh-571]: https://github.com/jrblevin/markdown-mode/issues/571
   [gh-584]: https://github.com/jrblevin/markdown-mode/issues/584
   [gh-587]: https://github.com/jrblevin/markdown-mode/issues/587
+  [gh-590]: https://github.com/jrblevin/markdown-mode/pull/590
 
 # Markdown Mode 2.4
 

markdown-mode.el

@@ -7839,35 +7839,37 @@ directory first, then in subdirectories if
 `markdown-wiki-link-search-subdirectories' is non-nil, and then
 in parent directories if
 `markdown-wiki-link-search-parent-directories' is non-nil."
-  (let* ((basename (replace-regexp-in-string
-                    "[[:space:]\n]" markdown-link-space-sub-char name))
-         (basename (if (derived-mode-p 'gfm-mode)
-                       (concat (upcase (substring basename 0 1))
-                               (downcase (substring basename 1 nil)))
-                     basename))
-         directory extension default candidates dir)
-    (when buffer-file-name
-      (setq directory (file-name-directory buffer-file-name)
-            extension (file-name-extension buffer-file-name)))
-    (setq default (concat basename
-                          (when extension (concat "." extension))))
-    (cond
-     ;; Look in current directory first.
-     ((or (null buffer-file-name)
-          (file-exists-p default))
-      default)
-     ;; Possibly search in subdirectories, next.
-     ((and markdown-wiki-link-search-subdirectories
-           (setq candidates
-                 (directory-files-recursively
-                  directory (concat "^" default "$"))))
-      (car candidates))
-     ;; Possibly search in parent directories as a last resort.
-     ((and markdown-wiki-link-search-parent-directories
-           (setq dir (locate-dominating-file directory default)))
-      (concat dir default))
-     ;; If nothing is found, return default in current directory.
-     (t default))))
+  (save-match-data
+    ;; This function must not overwrite match data(PR #590)
+    (let* ((basename (replace-regexp-in-string
+                      "[[:space:]\n]" markdown-link-space-sub-char name))
+           (basename (if (derived-mode-p 'gfm-mode)
+                         (concat (upcase (substring basename 0 1))
+                                 (downcase (substring basename 1 nil)))
+                       basename))
+           directory extension default candidates dir)
+      (when buffer-file-name
+        (setq directory (file-name-directory buffer-file-name)
+              extension (file-name-extension buffer-file-name)))
+      (setq default (concat basename
+                            (when extension (concat "." extension))))
+      (cond
+       ;; Look in current directory first.
+       ((or (null buffer-file-name)
+            (file-exists-p default))
+        default)
+       ;; Possibly search in subdirectories, next.
+       ((and markdown-wiki-link-search-subdirectories
+             (setq candidates
+                   (directory-files-recursively
+                    directory (concat "^" default "$"))))
+        (car candidates))
+       ;; Possibly search in parent directories as a last resort.
+       ((and markdown-wiki-link-search-parent-directories
+             (setq dir (locate-dominating-file directory default)))
+        (concat dir default))
+       ;; If nothing is found, return default in current directory.
+       (t default)))))
 
 (defun markdown-follow-wiki-link (name &optional other)
   "Follow the wiki link NAME.

tests/markdown-test.el

@@ -6352,6 +6352,23 @@ x|"
             (markdown-test-range-has-property 19 26 'font-lock-face 'markdown-link-face))
         (kill-buffer)))))
 
+(ert-deftest test-markdown-ext/wiki-link-keep-match-data ()
+  "Test that markdown-wiki-link-p keeps expected match data.
+Detail: https://github.com/jrblevin/markdown-mode/pull/590"
+  (let ((markdown-enable-wiki-links t)
+        (markdown-link-space-sub-char " ")
+        (markdown-wiki-link-search-subdirectories t))
+    (progn
+      (find-file "wiki/pr590/Guide.md")
+      (unwind-protect
+          (progn
+            (markdown-mode)
+            (re-search-forward "Zettel Markdown")
+            (goto-char (match-beginning 0))
+            (should (markdown-wiki-link-p))
+            (should (string= (markdown-wiki-link-link) "Zettel Markdown")))
+        (kill-buffer)))))
+
 (ert-deftest test-markdown-ext/wiki-link-major-mode ()
   "Test major-mode of linked page."
   (let ((markdown-enable-wiki-links t)

tests/wiki/pr590/Guide.md

@@ -0,0 +1 @@
+**Basics**: A neuron notebook is just a directory of [[Zettel Markdown]] files

tests/wiki/pr590/Guide/Zettel Markdown.md

@@ -0,0 +1,2 @@
+Zettel files are written in Markdown
+

tests/wiki/pr590/Guide/Zettel Markdown/math.md

@@ -0,0 +1 @@
+# Math support