bug#20144: 25.0.50; Functions using fboundp not known to be defined

[Philipp Stephani <p.stephani2@gmail.com>]

Byte-compiling the following file:

(if (fboundp 'car)
    (defalias 'mycar 'car)
  (defun mycar (_l) (error "what")))

(defun foo ()
  (mycar nil))

results in the byte compiler warning

  Warning: the function `mycar' is not known to be defined.

However, the function is clearly always defined.  Since this trick is
rather common, the byte compiler should know about it.



In GNU Emacs 25.0.50.1 (x86_64-pc-linux-gnu, GTK+ Version 3.10.8)
 of 2014-12-01 on *hidden*, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11501000
System Description:	Ubuntu 14.04 LTS

Configured using:
 `configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
 --enable-locallisppath=/etc/emacs-snapshot:/etc/emacs:/usr/local/share/emacs/25.0.50/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/25.0.50/site-lisp:/usr/share/emacs/site-lisp
 --with-crt-dir=/usr/lib/x86_64-linux-gnu --build x86_64-linux-gnu
 --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
 --enable-locallisppath=/etc/emacs-snapshot:/etc/emacs:/usr/local/share/emacs/25.0.50/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/25.0.50/site-lisp:/usr/share/emacs/site-lisp
 --with-crt-dir=/usr/lib/x86_64-linux-gnu --with-x=yes
 --with-x-toolkit=gtk3 --with-toolkit-scroll-bars 'CFLAGS=-g -O2
 -fstack-protector --param=ssp-buffer-size=4 -Wformat
 -Werror=format-security -Wall' CPPFLAGS=-D_FORTIFY_SOURCE=2
 'LDFLAGS=-Wl,-Bsymbolic-functions -Wl,-z,relro''

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GCONF GSETTINGS
NOTIFY LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB

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

Major mode: Emacs-Lisp

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
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Making completion list...
You can run the command `emacs-lisp-mode' with M-x e-li-mo RET
next-line: End of buffer
Quit
Saving file /tmp/bytetest.el...
Wrote /tmp/bytetest.el
Compiling /tmp/bytetest.el...done
Wrote /tmp/bytetest.elc

Load-path shadows:
None found.

Features:
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Memory information:
((conses 16 88229 4854)
 (symbols 48 19489 0)
 (miscs 40 57 185)
 (strings 32 15003 4186)
 (string-bytes 1 456733)
 (vectors 16 11046)
 (vector-slots 8 406209 3506)
 (floats 8 77 239)
 (intervals 56 295 16)
 (buffers 976 14)
 (heap 1024 36642 863))