1. From emacs -Q, open this file: https://github.com/zephyrproject-rtos/zephyr/blob/2de59023dc726e61244eb7cca17252294016c65a/subsys/net/lib/http/http_client.c 2. Observe incorrect syntax highlighting at beginning of file. Screenshot: https://postimg.org/image/tzy8qgjjz/ (Note that loading a C file with just the #ifdefs and initial comment which fail to highlight above doesn't reproduce the issue.) In GNU Emacs 26.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.11) of 2017-08-10 built on plop Repository revision: 81656add8117e8d1b7faab18b330d0706462b433 Windowing system distributor 'The X.Org Foundation', version 11.0.11903000 System Description: Ubuntu 17.04 Recent messages: For information about GNU Emacs and the GNU system, type C-h C-a. Making completion list... mwheel-scroll: Beginning of buffer [21 times] Making completion list... Configured using: 'configure --without-pop' Configured features: XPM JPEG TIFF GIF PNG SOUND DBUS GSETTINGS NOTIFY GNUTLS FREETYPE XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 Important settings: value of $LANG: en_US.UTF-8 value of $XMODIFIERS: @im=ibus locale-coding-system: utf-8-unix Major mode: C/*l Minor modes in effect: diff-auto-refine-mode: t 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 subr-x 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 vc-git diff-mode easy-mmode 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 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 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 123261 11555) (symbols 48 22839 1) (miscs 40 60 140) (strings 32 35859 1155) (string-bytes 1 1079093) (vectors 16 17814) (vector-slots 8 527552 12359) (floats 8 52 134) (intervals 56 1378 3) (buffers 992 13))