bug#35454: 26.2.50; CC-Mode fontification fails inside macro

[Mauro Aranda <maurooaranda@gmail.com>]

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Hello.

Steps to reproduce:
1) emacs -Q
2) Open up a new .c file:
C-x C-f test.c
3) Type this text:
#define FOO        \
  /* Some comms.  */     \
  struct foobar my_foo; \
  struct foobar my_bar;

The first struct foobar after the comment is not fontified as the second
one.  That is, the second foobar has face font-lock-type-face, and
my_bar has face font-lock-variable-name-face, but the first foobar and
my_foo don't get those face values.

I actually bumped into this issue while visiting the emacs source file
src/editfns.c.  In that file, search for "#define EXTRA_CONTEXT_FIELDS"
and the problem should be evident.

I can reproduce it with the latest Emacs 26, as well as with the latest
master:
Repository revision: 8dc00b2f1e6523c634df3e24379afbe712a32b27
Repository branch: master

Best regards,
Mauro.


In GNU Emacs 26.2.50 (build 1, i686-pc-linux-gnu, GTK+ Version 3.18.9)
 of 2019-04-23 built on the-blackbeard
Repository revision: 9ec18fbd560526ab19c6171aff15995d1307233e
Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
System Description:    Ubuntu 16.04.6 LTS

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
(New file)
Auto-saving...done
Quit
Making completion list...

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS GLIB
NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM THREADS LCMS2

Important settings:
  value of $LANG: en_US.utf8
  value of $XMODIFIERS:
  locale-coding-system: utf-8-unix

Major mode: C/*l

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
  transient-mark-mode: t
  abbrev-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny seq byte-opt gv
bytecomp byte-compile cconv dired dired-loaddefs format-spec rfc822 mml
mml-sec password-cache epa derived epg epg-config 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 cc-mode cc-fonts easymenu cc-guess
cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs
cl-loaddefs cl-lib elec-pair time-date 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 charprop 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 threads dbusbind inotify lcms2 dynamic-setting
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 8 115795 11061)
 (symbols 24 22635 1)
 (miscs 20 58 184)
 (strings 16 34126 1595)
 (string-bytes 1 1031562)
 (vectors 12 17262)
 (vector-slots 4 561150 8896)
 (floats 8 51 121)
 (intervals 28 306 68)
 (buffers 536 13)
 (heap 1024 38012 1009))

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