master 34e7617 1/2: Respect :must-match for file types in customization buffers

[Lars Ingebrigtsen]

branch: master
commit 34e7617365f16f9dfa6f31f968a0b5dee6d7d54b
Author: Mauro Aranda <maurooaranda@gmail.com>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Respect :must-match for file types in customization buffers
    
    * lisp/wid-edit.el (file widget): Add a :match and a :validate
    function to the 'file widget, to be able to check if the widget
    value is an existent file, when required (bug#25678).
---
 lisp/wid-edit.el | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lisp/wid-edit.el b/lisp/wid-edit.el
index ea7e266..f58a0fb 100644
--- a/lisp/wid-edit.el
+++ b/lisp/wid-edit.el
@@ -3161,6 +3161,15 @@ It reads a file name from an editable text field."
   :completions (completion-table-case-fold
                 #'completion-file-name-table
                 (not read-file-name-completion-ignore-case))
+  :match (lambda (widget value)
+           (or (not (widget-get widget :must-match))
+               (file-exists-p value)))
+  :validate (lambda (widget)
+              (let ((value (widget-value widget)))
+                (unless (widget-apply widget :match value)
+                  (widget-put widget
+                              :error (format "File %s does not exist" value))
+                  widget)))
   :prompt-value 'widget-file-prompt-value
   :format "%{%t%}: %v"
   ;; Doesn't work well with terminating newline.