* doc/lispref/variables.texi (Scope): Mention the availability of lexbind.

(Lexical Binding): New node.
* doc/lispref/eval.texi (Eval): Add `eval's new `lexical' arg.
* lisp/emacs-lisp/cconv.el (cconv-liftwhen): Increase threshold.
(cconv-closure-convert-rec): Convert interactive spec in empty lexenv.
(cconv-analyse-use): Improve unused vars warnings.
(cconv-analyse-form): Analyze interactive spec in empty lexenv.
* lisp/emacs-lisp/bytecomp.el (byte-compile-lambda): Always byte-compile
the interactive spec in lexical-binding mode.
(byte-compile-refresh-preloaded): Don't reload byte-compiler files.
* lisp/custom.el (custom-initialize-default): Use defvar.
(custom-declare-variable): Set the special-variable-p flag.
* lisp/help-fns.el (help-make-usage): Drop leading underscores.
* lisp/dired.el (dired-revert, dired-make-relative): Mark unused args.
(dired-unmark-all-files): Remove unused var `query'.
(dired-overwrite-confirmed): Declare.
(dired-restore-desktop-buffer): Don't use dynamically scoped arg names.
* lisp/mpc.el: Mark unused args.
(mpc--faster-toggle): Remove unused var `songnb'.
* lisp/server.el (server-kill-buffer-running): Move before first use.
* lisp/minibuffer.el: Mark unused args.
* src/callint.c (quotify_arg): Simplify the logic.
(Fcall_interactively): Use lexical binding when evaluating the
interactive spec of a lexically bound function.

lisp/emacs-lisp/byte-opt.el

@@ -308,6 +308,10 @@
 
 ;; ((lambda ...) ...)
 (defun byte-compile-unfold-lambda (form &optional name)
+  ;; In lexical-binding mode, let and functions don't bind vars in the same way
+  ;; (let obey special-variable-p, but functions don't).  This doesn't matter
+  ;; here, because function's behavior is underspecified so it can safely be
+  ;; turned into a `let', even though the reverse is not true.
   (or name (setq name "anonymous lambda"))
   (let ((lambda (car form))
 	(values (cdr form)))