Don't forget to analyze args of lambda lifted functions (Bug#30872)

* lisp/emacs-lisp/cconv.el (cconv--convert-funcbody): New function.
(cconv--convert-function): Extracted from here.
(cconv-convert): Also use it here, in the lambda lifted case, so that
mutated args are properly accounted for.
* test/lisp/emacs-lisp/cconv-tests.el: New test.

test/lisp/emacs-lisp/cconv-tests.el

@@ -0,0 +1,40 @@
+;;; cconv-tests.el -*- lexical-binding: t -*-
+
+;; Copyright (C) 2018 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+(require 'ert)
+
+(ert-deftest cconv-convert-lambda-lifted ()
+  "Bug#30872."
+  (should
+   (equal (funcall
+           (byte-compile
+            '#'(lambda (handle-fun arg)
+                 (let* ((subfun
+                         #'(lambda (params)
+                             (ignore handle-fun)
+                             (funcall #'(lambda () (setq params 42)))
+                             params)))
+                   (funcall subfun arg))))
+           nil 99)
+          42)))
+
+(provide 'cconv-tests)
+;; cconv-tests.el ends here.