Implement 'func-arity'

* src/eval.c (Ffunc_arity, lambda_arity): New functions.
* src/bytecode.c (get_byte_code_arity): New function.
* src/lisp.h (get_byte_code_arity): Add prototype.

* doc/lispref/functions.texi (What Is a Function): Document
'func-arity'.

* etc/NEWS: Mention 'func-arity'.

* test/src/fns-tests.el (fns-tests-func-arity): New test set.

1 files changed, 11 insertions, 0 deletions

diff --git a/test/src/fns-tests.el b/test/src/fns-tests.el
index 861736995f4..688ff1f6bd9 100644
--- a/test/src/fns-tests.el
+++ b/test/src/fns-tests.el
@@ -208,3 +208,14 @@
   (should (string-version-lessp "foo1.25.5.png" "foo1.125.5"))
   (should (string-version-lessp "2" "1245"))
   (should (not (string-version-lessp "1245" "2"))))
+
+(ert-deftest fns-tests-func-arity ()
+  (should (equal (func-arity 'car) '(1 . 1)))
+  (should (equal (func-arity 'caar) '(1 . 1)))
+  (should (equal (func-arity 'format) '(1 . many)))
+  (require 'info)
+  (should (equal (func-arity 'Info-goto-node) '(1 . 3)))
+  (should (equal (func-arity (lambda (&rest x))) '(0 . many)))
+  (should (equal (func-arity (eval (lambda (x &optional y)) nil)) '(1 . 2)))
+  (should (equal (func-arity (eval (lambda (x &optional y)) t)) '(1 . 2)))
+  (should (equal (func-arity 'let) '(1 . unevalled))))