--text follows this line-- Starting in emacsc 26.1, the grep-regexp-alist stopped matching grep hits that have a colon in them, which breaks on windows for me, since the file paths always have a drive letter prepended. For example, the grep hit: c:/Users/my.name/src/project\src\kbhit.hpp:29:#include used to be matched by prior versions of emacs, but as of 26.1, the colon in the second character prevents this from being recognized as a grep match. I'm wondering if the regexp really needs to explicitly disallow colons here, since it did not before. In GNU Emacs 26.1 (build 1, x86_64-w64-mingw32) of 2018-05-29 built on TPW550S Windowing system distributor 'Microsoft Corp.', version 6.1.7601 Recent messages: Grep finished with matches found compilation-next-error: No grep hit here Searched 1 buffer; 3 matches for "bits" Quit Mark saved where search started 3 matches for "\_" Pattern: Quit previous-line: Beginning of buffer Grep finished with matches found Configured using: 'configure --without-compress-install --without-dbus --with-modules 'CFLAGS= -O2 -g3'' Configured features: XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS MODULES THREADS LCMS2 Important settings: value of $LANG: ENU locale-coding-system: cp1252 Major mode: Grep Minor modes in effect: ace-popup-menu-mode: t global-magit-file-mode: t global-git-commit-mode: t lisp-extra-font-lock-global-mode: t yas-global-mode: t yas-minor-mode: t workgroups-mode: t diff-hl-flydiff-mode: t global-diff-hl-mode: t 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