Fix Edebug's handling of dotted specs (bug#6415)

* lisp/emacs-lisp/cl-macs.el (cl-destructuring-bind): Use
cl-macro-list1 instead of cl-macro-list in Edebug spec.

* lisp/emacs-lisp/edebug.el (edebug-after-dotted-spec): Delete
unused variable.
(edebug-dotted-spec): Add docstring.
(edebug-match-specs): Allow &optional and &rest specs to
match nothing at the tail of a dotted form. Handle matches of
dotted form tails which return non-lists.

* test/lisp/emacs-lisp/edebug-tests.el (edebug-tests-dotted-forms):
New test.

* test/lisp/emacs-lisp/edebug-resources/edebug-test-code.el:
(edebug-test-code-use-destructuring-bind): New function.

2 files changed, 18 insertions, 0 deletions

diff --git a/test/lisp/emacs-lisp/edebug-resources/edebug-test-code.el b/test/lisp/emacs-lisp/edebug-resources/edebug-test-code.el
index f52a2b1896c..ca49dcd213d 100644
--- a/test/lisp/emacs-lisp/edebug-resources/edebug-test-code.el
+++ b/test/lisp/emacs-lisp/edebug-resources/edebug-test-code.el
@@ -126,5 +126,9 @@
   !start!(with-current-buffer (get-buffer-create "*edebug-test-code-buffer*")
     !body!(format "current-buffer: %s" (current-buffer))))
 
+(defun edebug-test-code-use-destructuring-bind ()
+  (let ((two 2) (three 3))
+    (cl-destructuring-bind (x . y) (cons two three) (+ x!x! y!y!))))
+
 (provide 'edebug-test-code)
 ;;; edebug-test-code.el ends here
diff --git a/test/lisp/emacs-lisp/edebug-tests.el b/test/lisp/emacs-lisp/edebug-tests.el
index 02f4d1c5abe..f6c016cdf80 100644
--- a/test/lisp/emacs-lisp/edebug-tests.el
+++ b/test/lisp/emacs-lisp/edebug-tests.el
@@ -899,5 +899,19 @@ test and possibly others should be updated."
     "@g"  (should (equal edebug-tests-@-result
                          '(#("abcd" 1 3 (face italic)) 511))))))
 
+(ert-deftest edebug-tests-dotted-forms ()
+  "Edebug can instrument code matching the tail of a dotted spec (Bug#6415)."
+  (edebug-tests-with-normal-env
+   (edebug-tests-setup-@ "use-destructuring-bind" nil t)
+   (edebug-tests-run-kbd-macro
+    "@ SPC SPC SPC SPC SPC SPC"
+    (edebug-tests-should-be-at "use-destructuring-bind" "x")
+    (edebug-tests-should-match-result-in-messages "2 (#o2, #x2, ?\\C-b)")
+    "SPC"
+    (edebug-tests-should-be-at "use-destructuring-bind" "y")
+    (edebug-tests-should-match-result-in-messages "3 (#o3, #x3, ?\\C-c)")
+    "g"
+    (should (equal edebug-tests-@-result 5)))))
+
 (provide 'edebug-tests)
 ;;; edebug-tests.el ends here