Starting with Emacs 28, I have been seeing font-lock issues when editing C and C++ code. The situation where I see this the most (though I'm not sure if it's the only situation) is when I am writing a comment and currently have a space at the end of the comment line: in this situation, the fontification of a variable name or function name on the next line becomes broken until I type a non-space character to end the current line. The attached screen shots illustrate the problem: nospaces.png shows the correct fontification; space_before_var.png and space_before_function.png show that variable and function names lose their fontification when there is a space at the end of the previous comment line. Running M-x font-lock-fontify-buffer temporarily fixes the issue. The problem occurs even when using emacs -Q. I have tried the latest emacs28 pretest and the latest nightly build available from emacsformacosx (though with my customizations – NOT with emacs -Q) and those also exhibit the problem. The latest emacs27 from emacsformacosx does NOT have this issue. (I have also been seeing slightly similar font-lock issues when editing python code with Emacs 28. There, I get inconsistent fontification of variables: variables sometimes are not fontified with font-lock-variable-name-face when I initially load a file, but then if I edit a line – e.g., by adding a space at the end of the line – then the variable defined on that line will become properly fontified. I realize that this may be a separate issue that may warrant its own bug report, but I thought I'd mention it in case it's related.) Thank you, Bill In GNU Emacs 28.1 (build 2, aarch64-apple-darwin21.5.0, NS appkit-2113.50 Version 12.4 (Build 21F79)) of 2022-07-19 built on cgdm-green Windowing system distributor 'Apple', version 10.3.2113 System Description: macOS 12.4 Configured using: 'configure --disable-dependency-tracking --disable-silent-rules --enable-locallisppath=/opt/homebrew/share/emacs/site-lisp --infodir=/opt/homebrew/Cellar/emacs-plus@28/28.1/share/info/emacs --prefix=/opt/homebrew/Cellar/emacs-plus@28/28.1 --with-xml2 --with-gnutls --with-native-compilation --without-dbus --without-imagemagick --with-modules --with-rsvg --with-ns --disable-ns-self-contained 'CFLAGS=-Os -w -pipe -mmacosx-version-min=12 -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX12.sdk' 'CPPFLAGS=-I/opt/homebrew/opt/zlib/include -I/opt/homebrew/opt/icu4c/include -I/opt/homebrew/opt/sqlite/include -I/opt/homebrew/opt/openssl@1.1/include -I/opt/homebrew/opt/readline/include -I/opt/homebrew/opt/libffi/include -isystem/opt/homebrew/include -F/opt/homebrew/Frameworks -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX12.sdk' 'LDFLAGS=-L/opt/homebrew/opt/zlib/lib -L/opt/homebrew/opt/icu4c/lib -L/opt/homebrew/opt/sqlite/lib -L/opt/homebrew/opt/openssl@1.1/lib -L/opt/homebrew/opt/readline/lib -L/opt/homebrew/opt/libffi/lib -L/opt/homebrew/lib -F/opt/homebrew/Frameworks -Wl,-headerpad_max_install_names -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX12.sdk'' Configured features: ACL GLIB GMP GNUTLS JPEG JSON LCMS2 LIBXML2 MODULES NATIVE_COMP NOTIFY KQUEUE NS PDUMPER PNG RSVG THREADS TIFF TOOLKIT_SCROLL_BARS XIM ZLIB Important settings: value of $LANG: en_US.UTF-8 locale-coding-system: utf-8-unix Major mode: C/*l Minor modes in effect: tooltip-mode: t global-eldoc-mode: t show-paren-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 indent-tabs-mode: t transient-mark-mode: t abbrev-mode: t Load-path shadows: None found. Features: (shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs rfc822 mml mml-sec epa derived epg rfc6068 epg-config gnus-util rmail rmail-loaddefs auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs password-cache json map text-property-search seq byte-opt gv bytecomp byte-compile cconv mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils time-date subr-x jka-compr info vc-dispatcher vc-svn cc-mode cc-fonts cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs cl-loaddefs cl-lib iso-transl tooltip eldoc paren electric uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel term/ns-win ns-win ucs-normalize mule-util term/common-win tool-bar dnd fontset image regexp-opt fringe tabulated-list replace newcomment text-mode lisp-mode prog-mode register page tab-bar menu-bar rfn-eshadow isearch easymenu timer select scroll-bar mouse jit-lock font-lock syntax font-core term/tty-colors frame minibuffer 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 emoji-zwj charscript charprop case-table epa-hook jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice button loaddefs faces cus-face macroexp files window text-properties overlay sha1 md5 base64 format env code-pages mule custom widget hashtable-print-readable backquote threads kqueue cocoa ns lcms2 multi-tty make-network-process native-compile emacs) Memory information: ((conses 16 107172 9071) (symbols 48 8698 0) (strings 32 28953 1830) (string-bytes 1 1020321) (vectors 16 16903) (vector-slots 8 352351 17895) (floats 8 29 38) (intervals 56 546 0) (buffers 992 13))