Fix describe function arglist for native compiled lisp/d (bug#42572)

	* lisp/help.el (help-function-arglist): Handle the case of native
	compiled lisp/d.

	* src/data.c (syms_of_data): Register new subrs.
	(Fsubr_native_dyn_p, Fsubr_native_lambda_list): New primitives.

	* test/src/comp-tests.el (comp-tests-dynamic-help-arglist): New test.

1 files changed, 7 insertions, 0 deletions

diff --git a/test/src/comp-tests.el b/test/src/comp-tests.el
index 2a078be8cb0..b147bd6789c 100644
--- a/test/src/comp-tests.el
+++ b/test/src/comp-tests.el
@@ -582,6 +582,13 @@ https://lists.gnu.org/archive/html/bug-gnu-emacs/2020-03/msg00914.html."
   (should (equal '(2 . many)
                  (func-arity #'comp-tests-ffuncall-callee-opt-rest-dyn-f))))
 
+(ert-deftest comp-tests-dynamic-help-arglist ()
+  "Test `help-function-arglist' works on lisp/d (bug#42572)."
+  (should (equal (help-function-arglist
+                  (symbol-function #'comp-tests-ffuncall-callee-opt-rest-dyn-f)
+                  t)
+                 '(a b &optional c &rest d))))
+
 (ert-deftest comp-tests-cl-macro-exp ()
   "Verify CL macro expansion (bug#42088)."
   (should (equal (comp-tests-cl-macro-exp-f) '(a b))))