Switch to an empty buffer and enable c++-mode. Add the following content
to the buffer:

struct foo : public bar {
  foo() {}

  ~foo() {}
};

Everything is fine. Then add the keyword `override' to the destructor.

struct foo : public bar {
  foo() {}

  ~foo() override {}
};

Now ~foo is no more fontified...


In GNU Emacs 25.1.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.20.9)
 of 2016-08-19 built on carbon
Repository revision: 4a80c8bb276de0fdb1f9ddb8f1c1cf7d57d30918
Windowing system distributor 'The X.Org Foundation', version 
11.0.11804000
System Description:	Arch Linux

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GCONF GSETTINGS
NOTIFY ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 LIBSYSTEMD

Important settings:
  value of $LANG: fr_FR.UTF-8
  value of $XMODIFIERS: @im=ibus
  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
  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 cl-macs subr-x puny seq byte-opt
bytecomp byte-compile cl-extra help-mode 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 gv cl-loaddefs pcase cl-lib 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 newcomment elisp-mode lisp-mode prog-mode register page
menu-bar rfn-eshadow 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 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
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 16 118451 10206)
 (symbols 48 23038 0)
 (miscs 40 114 154)
 (strings 32 23517 3887)
 (string-bytes 1 842104)
 (vectors 16 16887)
 (vector-slots 8 475279 3482)
 (floats 8 193 121)
 (intervals 56 354 97)
 (buffers 976 12))