bug#26406: 26.0.50; 'function' fails as variable name inside lexical-let

[David Bremner]

0) Put the following elisp in a file called e.g. test.el
(eval-when-compile (require 'cl))
(defun my-fun (function)
  (lexical-let ((x 1))
    (funcall function)))

1) run "emacs -Q --batch -f batch-byte-compile test.el"

2) Observe the following unhelpful error message

In toplevel form:
test.el:2:1:Error: Wrong type argument: listp, cl--function-convert

This is minimally a behaviour change since emacs 25.1.

I tested against current master branch (hash 5f319eb3a)

In GNU Emacs 26.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, Xaw3d scroll 
bars)
 of 2017-04-08 built on zancas
Repository revision: c5f319eb3a2e0ad97867c8dc61bfc140333fb11d
System Description:     Debian GNU/Linux 9.0 (stretch)

Recent messages:
Loading /home/bremner/.emacs.d/custom.el (source)...done
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure --without-pop'

Configured features:
XAW3D XPM JPEG TIFF GIF PNG RSVG SOUND GPM DBUS GCONF GSETTINGS NOTIFY
ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS LUCID X11

Important settings:
  value of $LANG: en_CA.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message puny dired dired-loaddefs
format-spec rfc822 mml mml-sec epa derived epg gnus-util rmail
rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils term/rxvt term/xterm xterm time-date
warnings finder-inf package epg-config url-handlers url-parse
auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs
password-cache url-vars seq byte-opt subr-x gv bytecomp byte-compile
cl-extra help-mode easymenu cconv cl-loaddefs pcase cl-lib mule-util
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode
lisp-mode prog-mode register page menu-bar rfn-eshadow isearch timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript case-table epa-hook jka-cmpr-hook help
simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs button
faces cus-face macroexp files text-properties overlay sha1 md5 base64
format env code-pages mule custom widget hashtable-print-readable
backquote dbusbind inotify dynamic-setting x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 125804 6927)
 (symbols 48 22946 1)
 (miscs 40 86 116)
 (strings 32 25338 4515)
 (string-bytes 1 791650)
 (vectors 16 16167)
 (vector-slots 8 484127 2556)
 (floats 8 58 351)
 (intervals 56 200 0)
 (buffers 976 14))

-- 
David Bremner                                  Professor, UNB Computer Science
bremner@unb.ca                             
http://www.cs.unb.ca/~bremner               Cross Appointment, UNB Mathematics