* lisp/emacs-lisp/bytecomp.el (byte-compile-force-lexical-warnings): New var.

(byte-compile-preprocess): Use it.
(byte-compile-file-form-defalias): Try a bit harder to use macros we
can't quite recognize.
(byte-compile-add-to-list): Remove.
* lisp/emacs-lisp/cconv.el (cconv-warnings-only): New function.
(cconv-closure-convert): Add assertion.

* lisp/emacs-lisp/map-ynp.el: Use lexical-binding.
(map-y-or-n-p): Remove unused vars `tail' and `object'.
Factor out some repeated code.
* etc/NEWS (utf-8 for el): Move to the incompatible section.

1 files changed, 13 insertions, 1 deletions

diff --git a/lisp/emacs-lisp/cconv.el b/lisp/emacs-lisp/cconv.el
index 761e33c059d..70fa71a0da4 100644
--- a/lisp/emacs-lisp/cconv.el
+++ b/lisp/emacs-lisp/cconv.el
@@ -143,7 +143,19 @@ Returns a form where all lambdas don't have any free variables."
     ;; Analyze form - fill these variables with new information.
     (cconv-analyse-form form '())
     (setq cconv-freevars-alist (nreverse cconv-freevars-alist))
-    (cconv-convert form nil nil))) ; Env initially empty.
+    (prog1 (cconv-convert form nil nil) ; Env initially empty.
+      (cl-assert (null cconv-freevars-alist)))))
+
+;;;###autoload
+(defun cconv-warnings-only (form)
+  "Add the warnings that closure conversion would encounter."
+  (let ((cconv-freevars-alist '())
+	(cconv-lambda-candidates '())
+	(cconv-captured+mutated '()))
+    ;; Analyze form - fill these variables with new information.
+    (cconv-analyse-form form '())
+    ;; But don't perform the closure conversion.
+    form))
 
 (defconst cconv--dummy-var (make-symbol "ignored"))