Allow the newline character in the character widget (Bug#15925)

* lisp/wid-edit.el (widget-specify-field): Extend check for adding the
boundary overlay.  Plus, a minor comment indentation fix.
(character widget): Tweak the valid-regexp to allow the newline
character.

* test/lisp/wid-edit-tests.el (widget-test-character-widget-value)
(widget-test-editable-field-widget-value): New tests (bug#15925).

2 files changed, 23 insertions, 4 deletions

diff --git a/lisp/wid-edit.el b/lisp/wid-edit.el
index 13d850a57f5..8ad99f49aa1 100644
--- a/lisp/wid-edit.el
+++ b/lisp/wid-edit.el
@@ -303,12 +303,15 @@ the :notify function can't know the new value.")
          (or (not widget-field-add-space) (widget-get widget :size))))
     (if (functionp help-echo)
       (setq help-echo 'widget-mouse-help))
-    (when (= (char-before to) ?\n)
+    (when (and (or (> to (1+ from)) (null (widget-get widget :size)))
+               (= (char-before to) ?\n))
       ;; When the last character in the field is a newline, we want to
       ;; give it a `field' char-property of `boundary', which helps the
       ;; C-n/C-p act more naturally when entering/leaving the field.  We
-     ;; do this by making a small secondary overlay to contain just that
-      ;; one character.
+      ;; do this by making a small secondary overlay to contain just that
+      ;; one character.  BUT we only do this if there is more than one
+      ;; character (so we don't do this for the character widget),
+      ;; or if the size of the editable field isn't specified.
       (let ((overlay (make-overlay (1- to) to nil t nil)))
         (overlay-put overlay 'field 'boundary)
         ;; We need the real field for tabbing.
@@ -3524,7 +3527,7 @@ To use this type, you must define :match or :match-alternatives."
   :value 0
   :size 1
   :format "%{%t%}: %v\n"
-  :valid-regexp "\\`.\\'"
+  :valid-regexp "\\`\\(.\\|\n\\)\\'"
   :error "This field should contain a single character"
   :value-get (lambda (w) (widget-field-value-get w t))
   :value-to-internal (lambda (_widget value)
diff --git a/test/lisp/wid-edit-tests.el b/test/lisp/wid-edit-tests.el
index 2ddb656fa9e..df49ffc8224 100644
--- a/test/lisp/wid-edit-tests.el
+++ b/test/lisp/wid-edit-tests.el
@@ -113,4 +113,20 @@
         (should (eq (current-column)
                     (widget-get grandchild :indent)))))))
 
+(ert-deftest widget-test-character-widget-value ()
+  "Check that we get the character widget's value correctly."
+  (with-temp-buffer
+    (let ((wid (widget-create '(character :value ?\n))))
+      (goto-char (widget-get wid :from))
+      (should (string= (widget-apply wid :value-get) "\n"))
+      (should (char-equal (widget-value wid) ?\n))
+      (should-not (widget-apply wid :validate)))))
+
+(ert-deftest widget-test-editable-field-widget-value ()
+  "Test that we get the editable field widget's value correctly."
+  (with-temp-buffer
+    (let ((wid (widget-create '(editable-field :value ""))))
+      (widget-insert "And some non-widget text.")
+      (should (string= (widget-apply wid :value-get) "")))))
+
 ;;; wid-edit-tests.el ends here