Emacs NEWS.27

Table of Contents

GNU Emacs NEWS – history of user-visible changes.

Copyright (C) 2017-2023 Free Software Foundation, Inc. See the end of the file for license conditions.

Please send Emacs bug reports to 'bug-gnu-emacs@gnu.org'. If possible, use 'M-x report-emacs-bug'.

This file is about changes in Emacs version 27.

See file HISTORY for a list of GNU Emacs versions and release dates. See files NEWS.26, NEWS.25, …, NEWS.18, and NEWS.1-17 for changes in older Emacs versions.

You can narrow news to a specific version by calling view-emacs-news with a prefix argument or by typing 'C-u C-h C-n'.

1. Changes in Emacs 27.2

This is a bug-fix release with no new features.

2. Lisp Changes in Emacs 27.2

2.1. The behavior of the user option resize-mini-frames has changed.

If set to a non-nil value which isn't a function, resize the mini frame using the new function fit-mini-frame-to-buffer which won't skip leading or trailing empty lines of the buffer.


2.2. Update IRC-related references to point to Libera.Chat.

In June 2021, the Free Software Foundation and the GNU Project moved their official IRC channels from the Freenode network to Libera.Chat in the aftermath of the changes in Freenode's governance structure and policies in May and June 2021. The decision-making process took into account the feedback received from the community against a set of criteria devised by a working group drawn from both GNU and the FSF to gauge a chat network's acceptability to software freedom activists.

For the original announcement and the follow-up update, including more details, see:

https://lists.gnu.org/archive/html/info-gnu/2021-06/msg00005.html https://lists.gnu.org/archive/html/info-gnu/2021-06/msg00007.html

Given the relocation of GNU and FSF's official IRC channels, as well as #emacs and various other Emacs-themed channels (see the link below) to Libera.Chat, IRC-related references in the Emacs repository have now been updated to point to Libera.Chat.


3. Changes in Specialized Modes and Packages in Emacs 27.2

3.1. Tramp

3.1.1. The user option 「tramp-completion-reread-directory-timeout」 is now obsolete.

4. Changes in Emacs 27.2 on Non-Free Operating Systems

4.1. Emacs now ignores modifier keys when IME input is used.

By default, pressing Ctrl, Shift, and Alt keys while using IME input will no longer apply the modifiers to the produced characters, as there are IMEs which use keys with modifiers to input some characters. Customize the variable w32-ignore-modifiers-on-IME-input to nil to get back the old behavior.

5. Installation Changes in Emacs 27.1

5.1. Emacs now uses GMP, the GNU Multiple Precision library.

By default, if 'configure' does not find a suitable libgmp, it arranges for the included mini-gmp library to be built and used. The new configure option '–without-libgmp' uses mini-gmp even if a suitable libgmp is available.

5.2. Emacs can now use HarfBuzz as its shaping engine.

The new configure option '–with-harfbuzz' adds support for the HarfBuzz text shaping engine. It is on by default; use './configure –without-harfbuzz' to build without it. The HarfBuzz text shaping is available via new font backend drivers 'xfthb' and 'ftcrhb' for Xft and Cairo drawings, respectively, and via the 'harfbuzz' backend on MS-Windows. The HarfBuzz text shaping is preferred to the previously supported ones, so the font backends that use older shaping engines (FLT on GNU and Unix systems and Uniscribe on MS-Windows) are not enabled by default; they can be enabled via the 「font-backend」 frame parameter or via X resources.

5.3. The new configure option '–with-json' adds native support for JSON.

This uses the Jansson library. The option is on by default; use './configure –with-json=no' to build without Jansson support. The new JSON functions json-serialize, json-insert, json-parse-string, and json-parse-buffer are typically much faster than their Lisp counterparts from json.el.

5.4. The configure option '–with-cairo' is no longer experimental.

This builds Emacs with Cairo drawing, and supports built-in printing when Emacs is built with GTK+. Some severe bugs in this build were fixed, and we can therefore offer this to users without caveats. Note that building with Cairo enabled results in using Pango instead of libXft for font support, and that Pango 1.44 has removed support for bitmapped fonts.

5.5. Emacs now uses a "portable dumper" instead of unexec.

This improves compatibility with memory allocation on modern systems, and in particular better supports the Address Space Layout Randomization (ASLR) feature, a security technique used by most modern operating systems.

When built with the portable dumping support (which is the default), Emacs looks for the "emacs.pdmp" file, generated during the build, in its data directory at startup, and loads the dumped state from there. The new command-line argument '–dump-file=FILE' allows specifying a non-default ".pdmp" file to load the state from; see the node "(emacs) Initial Options" in the Emacs manual for more information.

An Emacs started via a dump file can create a new dump file only if it was invoked with the '-batch' option. (This is a temporary limitation; we plan on lifting it in a future release.)

Although the portable dumper has been tested, it may have a bug on unusual platforms. If you require traditional unexec dumping you can use the configure-time option '–with-dumping=unexec'; however, please file a bug report describing the situation, as unexec dumping is deprecated, and we plan on removing it in some future release.

5.6. The new configure option '–enable-checking=structs' attempts to

check that the portable dumper code has been updated to match the last change to one of the data structures that it relies on.

5.7. The configure options '–enable-checking=conslist' and

'–enable-checking=xmallocoverrun' have been withdrawn. The former made Emacs irredeemably slow, and the latter made it crash. Neither option was useful with modern debugging tools such as AddressSanitizer. (See "etc/DEBUG" for the details of using the modern replacements of the removed configure options.)

5.8. Emacs no longer defaults to using ImageMagick to display images.

This is due to security and stability concerns with ImageMagick. To override the default, use 'configure –with-imagemagick'.

5.9. Several configure options now accept an option-argument 'ifavailable'.

For example, './configure –with-xpm=ifavailable' now configures Emacs to attempt to use libxpm but to continue building even if libxpm is absent. The other affected options are '–with-gif', '–with-gnutls', '–with-jpeg', '–with-png', and '–with-tiff'.

5.10. The 'etags' program now uses the C library's regular expression matcher.

If it's possible, 'etags' will use the regexp matcher from the system's standard C library, otherwise it will be linked with a compatible regex substitute. This lets developers maintain Emacs's own regex code without having to also support other programs. The new configure option '–without-included-regex' forces 'etags' to use the C library's regex matcher even if the regex substitute ordinarily would be used to work around compatibility problems.

5.11. Emacs has been ported to the '-fcheck-pointer-bounds' option of GCC.

This causes Emacs to check bounds of some arrays addressed by its internal pointers, which can be helpful when debugging the Emacs interpreter or modules that it uses. If your platform supports it you can enable it when configuring, e.g., './configure CFLAGS="-g3 -O2 -mmpx -fcheck-pointer-bounds"' on Intel MPX platforms.

5.12. Emacs now normally uses a C pointer type instead of a C integer

type to implement LispObject, which is the fundamental machine word type internal to the Emacs Lisp interpreter. This change aims to catch typos and supports '-fcheck-pointer-bounds'. The configure option '–enable-check-lisp-object-type' is therefore no longer as useful and so is no longer enabled by default in developer builds, to reduce differences between developer and production builds.

5.13. The distribution tarball now has test cases; 'make check' runs them.

This is intended mostly to help developers.

5.14. Emacs now requires GTK 2.24 and GTK 3.10 for the GTK 2 and GTK 3

builds respectively.

5.15. New make target 'help' shows a summary of common make targets.

5.16. Emacs now builds with dynamic module support by default.

Pass '–without-modules' to 'configure' to disable dynamic module support.

5.17. The ftx font backend driver is now obsolete and will be removed in

Emacs 28.

6. Startup Changes in Emacs 27.1

6.1. Emacs can now use the XDG convention for init files.

The 'XDGCONFIGHOME' environment variable (which defaults to "~/.config") specifies the XDG configuration parent directory. Emacs checks for "init.el" and other configuration files inside the "emacs" subdirectory of 'XDGCONFIGHOME', i.e. "$XDGCONFIGHOME/emacs/init.el"

However, Emacs will still initially look for init files in their traditional locations if "~/.emacs.d" or "~/.emacs" exist, even if "$XDGCONFIGHOME/emacs" also exists. This means that you must delete or rename any existing "~/.emacs.d" and "~/.emacs" to enable use of the XDG directory.

If "~/.emacs.d" does not exist, and Emacs has decided to use it (i.e. "$XDGCONFIGHOME/emacs" does not exist), Emacs will create it. Emacs will never create "$XDGCONFIGHOME/emacs".

Whichever directory Emacs decides to use, it will set user-emacs-directory to point to it.

6.2. Emacs can now be configured using an early init file.

The file is called "early-init.el", in user-emacs-directory. It is loaded very early in the startup process: before graphical elements such as the tool bar are initialized, and before the package manager is initialized. The primary purpose is to allow customizing how the package system is initialized given that initialization now happens before loading the regular init file (see below).

We recommend against putting any customizations in this file that don't need to be set up before initializing installed add-on packages, because the early init file is read too early into the startup process, and some important parts of the Emacs session, such as window-system and other GUI features, are not yet set up, which could make some customization fail to work.

6.3. Installed packages are now activated before loading the init file.

As a result of this change, it is no longer necessary to call package-initialize in your init file.

Previously, a call to package-initialize was automatically inserted into the init file when Emacs was started. This call can now safely be removed. Alternatively, if you want to ensure that your init file is still compatible with earlier versions of Emacs, change it to:

(when (< emacs-major-version 27) (package-initialize))

However, if your init file changes the values of package-load-list or package-user-dir, or sets package-enable-at-startup to nil then it won't work right without some adjustment:

  • You can move that code to the early init file (see above), so those settings apply before Emacs tries to activate the packages.
  • You can use the new package-quickstart so activation of packages does not need to pay attention to package-load-list or package-user-dir any more.

6.4. Emacs now notifies systemd when startup finishes or shutdown begins.

Units that are ordered after 'emacs.service' will only be started after Emacs has finished initialization and is ready for use, and Emacs needs to be built with systemd support. (If your Emacs is installed in a non-standard location and you copied the "emacs.service" file to e.g. "~/.config/systemd/user/", you will need to copy the new version of the file again.)

7. Changes in Emacs 27.1

7.1. Emacs now supports Unicode Standard version 13.0.

7.2. Emacs now supports resizing and rotating images without ImageMagick.

All modern systems support this feature. (On GNU and Unix systems, Cairo drawing or the XRender extension to X11 is required for this to be available; the configure script will test for it and, if found, enable scaling.)

The new function image-transforms-p can be used to test whether any given frame supports these capabilities.

7.3. The Network Security Manager now allows more fine-grained control

of what checks to run via the 「network-security-protocol-checks」 user option.

7.4. TLS connections have their security tightened by default.

Most of the checks for outdated, believed-to-be-weak TLS algorithms and ciphers are now switched on by default. (In addition, several new TLS weaknesses are now warned about.) By default, the NSM will flag connections using these weak algorithms and ask users whether to allow them. To get the old behavior back (where certificates are checked for validity, but no warnings about weak cryptography are issued), you can either set 「network-security-protocol-checks」 to nil, or adjust the elements in that user option to only happen on the 'high' security level (assuming you use the 'medium' level).

7.5. New user option 「nsm-trust-local-network」.

Allows skipping Network Security Manager checks for hosts on your local subnet(s). It defaults to nil. Usually, there should be no need to set this non-nil, and doing that risks opening your local network connections to attacks. So be sure you know what you are doing before changing the value.

7.6. Native GnuTLS connections can now use client certificates.

Previously, this support was only available when using the external 「gnutls-cli」 or 'starttls' command. Call open-network-stream with ':client-certificate t' to trigger looking up of per-server certificates via 「auth-source」.

7.7. New user option 「network-stream-use-client-certificates」.

When non-nil, open-network-stream performs lookups of client certificates using 「auth-source」 as if ':client-certificate t' were specified if there is no explicit ':client-certificate' parameter. Defaults to nil.

7.8. 'next/previous-multiframe-window' have been renamed.

The new names are as follows:

next-multiframe-window -> next-window-any-frame previous-multiframe-window -> previous-window-any-frame

The old function names are maintained as aliases for backward compatibility.

7.9. emacsclient

7.9.1. emacsclient now supports the 'EMACSSOCKETNAME' environment variable.

The command-line argument '–socket-name' overrides it. (The same behavior as for the pre-existing 'EMACSSERVERFILE' variable.)

7.9.2. Emacs and emacsclient now default to "$XDGRUNTIMEDIR/emacs".

This is used as the directory for client/server sockets, if Emacs is running on a platform or environment that sets the 'XDGRUNTIMEDIR' environment variable to indicate where session sockets should go. To get the old, less-secure behavior, you can set the 'EMACSSOCKETNAME' environment variable to an appropriate value.

7.9.3. When run by root, emacsclient no longer connects to non-root sockets.

(Instead you can use Tramp methods to run root commands in a non-root Emacs.)

7.10. xft-ignore-color-fonts now ignores even more color fonts.

There are color fonts that managed to bypass the existing checks, causing XFT crashes, they are now filtered out. Setting xft-ignore-color-fonts to nil removes those checks, which might require setting face-ignored-fonts to filter out problematic fonts. Known problematic fonts are "Noto Color Emoji" and "Emoji One".

7.11. The GTK+ font chooser now respects face-ignored-fonts.

When using menu-set-font under GTK3, the available fonts are now matched against face-ignored-fonts.

7.12. The GTK+ font chooser now remembers the previously selected settings.

It now remembers the name, size, style, etc.

7.13. New user option what-cursor-show-names.

When non-nil, what-cursor-position will show the name of the character in addition to the decimal/hex/octal representation. Default nil.

7.14. New function network-lookup-address-info.

This does IPv4 and/or IPv6 address lookups on hostnames.

7.15. network-interface-list can now return IPv4 and IPv6 addresses.

IPv4 and IPv6 addresses are now returned by default if available, optionally including netmask/broadcast address information.

7.16. Control of the threshold for using the 「distant-foreground」 color.

The threshold for color distance below which the 「distant-foreground」 color of the face will be used instead of the foreground color can now be controlled via the new variable face-near-same-color-threshold. The default value is 30000, as the previously hard-coded threshold.

7.17. The function read-passwd uses "*" as default character to hide passwords.

7.18. The function read-answer now accepts not only single character

answers, but also function keys like 'F1', character events such as 'C-M-h', and control characters like 【C-h】.

7.19. Lexical binding is now used by default when evaluating interactive Elisp.

More specifically, lexical-binding is now used by default for 'M-:' and '–eval' (including in evaluations invoked from 'emacsclient' via its '–eval' command-line option), as well as in lisp-interaction-mode and 「ielm-mode」, used in the "scratch" and "ielm" buffers.

We envision that most Lisp code is already either written with lexical-binding in mind, or will work unchanged under lexical-binding. If, for some reason, your code used in 'M-:' or '–eval' doesn't work as result of this change, either modify the code to work with lexical binding, or wrap it in an extra level of 'eval'. For example, –eval "FORM" becomes –eval "(eval 'FORM)" (note the extra quote in 'FORM).

7.20. The new user option tooltip-resize-echo-area avoids truncating

tooltip text on GUI frames when tooltips are displayed in the echo area. Instead, it resizes the echo area as needed to accommodate the full tool-tip text.

7.21. Show mode line tooltips only if the corresponding action applies.

Customize the user option mode-line-default-help-echo to restore the old behavior where the tooltip text is also shown when the corresponding action does not apply.

7.22. New hook 「server-after-make-frame-hook」.

This hook is a convenient place to perform initializations in daemon mode which require GUI features to be available. One example is restoration of the previous session using the desktop.el package: put the call to desktop-read in this hook, if you want the GUI settings to be restored, or if desktop.el needs to interact with you during restoration of the session.

7.23. The functions set-frame-height and set-frame-width are now

commands, and will set the currently selected frame to the height/ width specified by the numeric prefix.

7.24. New function 'logcount' calculates an integer's Hamming weight.

7.25. New function libxml-available-p.

This function returns non-nil if libxml support is both compiled in and available at run time. Lisp programs should use this function to detect built-in libxml support, instead of testing for that indirectly, e.g., by checking that functions like libxml-parse-html-region return nil.

7.26. libxml-parse-xml-region and libxml-parse-html-region take

a parameter that's called DISCARD-COMMENTS, but it really only discards the top-level comment. Therefore this parameter is now obsolete, and the new utility function xml-remove-comments can be used to remove comments before calling the libxml functions to parse the data.

7.27. A new DOM (the XML/HTML document structure returned by functions

such as libxml-parse-html-region) traversal function has been added: dom-search, which takes a DOM and a predicate and returns all nodes that match.

7.28. New function fill-polish-nobreak-p, to be used in fill-nobreak-predicate.

It blocks line breaking after a one-letter word, also in the case when this word is preceded by a non-space, but non-alphanumeric character.

7.29. The limit on repetitions in regexps has been raised to 216-1.

It was previously limited to 215-1. For example, the following regular expression was previously invalid, but is now accepted:


7.30. The German prefix and postfix input methods now support Capital sharp S.

7.31. New input methods 「hawaiian-postfix」 and 「hawaiian-prefix」.

7.32. New input methods 「georgian-qwerty」 and 「georgian-nuskhuri」.

7.33. New input methods for several variants of the Sami language.

The Sami input methods include: 「norwegian-sami-prefix」, 「bergsland-hasselbrink-sami-prefix」, 「southern-sami-prefix」, 「ume-sami-prefix」, 「northern-sami-prefix」, 「inari-sami-prefix」, 「skolt-sami-prefix」, and 「kildin-sami-prefix」.

7.34. Japanese environments use UTF-8 by default.

In Japanese environments that do not specify encodings and are not based on MS-Windows, the default encoding is now utf-8 instead of japanese-iso-8bit.

7.35. New function exec-path.

This function by default returns the value of the corresponding user option, but can optionally return the equivalent of exec-path from a remote host.

7.36. The function executable-find supports an optional argument REMOTE.

This triggers searching for the program on the remote host as indicated by default-directory.

7.37. New user option auto-save-no-message.

When set to t, no message will be shown when auto-saving (default value: nil).

7.38. The value of make-cursor-line-fully-visible can now be a function.

In addition to nil or non-nil, the value can now be a predicate function. Follow mode uses this to control scrolling of its windows when the last screen line in a window is not fully visible.

7.39. New variable emacs-repository-branch.

It reports the git branch from which Emacs was built.

7.40. New user option switch-to-buffer-obey-display-actions.

When non-nil, switch-to-buffer uses pop-to-buffer-same-window that respects display actions specified by display-buffer-alist and display-buffer-overriding-action.

7.41. The user option switch-to-visible-buffer is now obsolete.

Customize switch-to-prev-buffer-skip instead.

7.42. New user option switch-to-prev-buffer-skip.

This user option allows specifying the set of buffers that may be shown by switch-to-prev-buffer and switch-to-next-buffer more stringently than the now obsolete switch-to-visible-buffer.

7.43. New 'flex' completion style.

An implementation of popular "flex/fuzzy/scatter" completion which matches strings where the pattern appears as a subsequence. Put simply, makes "foo" complete to both "barfoo" and "frodo". Add 'flex' to completion-styles or completion-category-overrides to use it.

7.44. The 「completion-common-part」 face is now visible by default.

7.45. New face attribute ':extend' to control face extension at EOL.

The new face attribute ':extend' controls whether to use the face for displaying the empty space beyond end of line (EOL) till the edge of the window. By default, this attribute is non-nil only for a small number of faces, notably, 'region'; any other face that crosses end of line will not affect the display of the empty space at EOL. This is to make Emacs behave more like other GUI applications with respect to displaying faces that cross line boundaries.

This attribute behaves specially when theme definitions are applied: if the theme doesn't specify an explicit value of this attribute for a face, the value from the original face definition is inherited. Consequently, a theme generally shouldn't specify this attribute unless it has a good reason to do so.

7.46. Connection-local variables

7.46.1. Connection-local variables are applied by default like file-local

and directory-local variables.

7.46.2. The macro with-connection-local-variables has been renamed from

「with-connection-local-profiles」. No argument PROFILES needed any longer.

7.47. New user option next-error-verbose controls when next-error

outputs a message about the error locus.

7.48. New user option 「grep-search-path」 defines the directories searched for

grep hits (this used to be controlled by compilation-search-path).

7.49. New user option emacs-lisp-compilation-search-path defines the

directories searched for byte-compiler error messages (this used to be controlled by compilation-search-path).

7.50. Multicolor fonts such as "Noto Color Emoji" can be displayed on

Emacs configured with Cairo drawing and linked with cairo >= 1.16.0.

7.51. Emacs now optionally displays a fill column indicator.

This is similar to what 「fill-column-indicator」 package provides, but much faster and compatible with show-trailing-whitespace.

Customize the buffer-local user options display-fill-column-indicator and display-fill-column-indicator-character to activate the indicator.

The indicator is not displayed at all in minibuffer windows and in tooltips, as it is not useful there.

There are 2 new buffer local variables and 1 face to customize this mode, they are described in the manual "(emacs) Display".

7.52. progress-reporter-update now accepts an optional suffix string to display.

7.53. New user option 「xref-file-name-display」 controls the display of

file names in xref buffers.

7.54. New user option byte-count-to-string-function.

It is used for displaying file sizes and disk space in some cases.

7.55. Emacs now interprets RGB triplets like HTML, SVG, and CSS do.

The X convention previously used differed slightly, particularly for RGB triplets with a single hexadecimal digit per component.

7.56. The toolbar now shows the equivalent key binding in its tooltips.

7.57. The File menu-bar menu was re-arranged.

Print menu items moved to submenu, and also added the new entries for tabs.

7.58. scroll-lock-mode is now bound to the 'ScrollLock' key globally.

Note that this key binding will not work on MS-Windows systems if w32-scroll-lock-modifier is non-nil.

7.59. global-set-key, called interactively, now no longer downcases a

key binding with an upper case letter - if you can type it, you can bind it.

7.60. read-from-minibuffer now works with buffer-local history variables.

The HIST argument of read-from-minibuffer now works correctly with buffer-local variables. This means that different buffers can have their own separated input history list if desired.

7.61. backup-by-copying-when-privileged-mismatch applies to file gid, too.

In addition to checking the file owner uid, Emacs also checks that the group gid is not greater than backup-by-copying-when-privileged-mismatch; if so, backup-by-copying-when-mismatch will be forced on.

8. Editing Changes in Emacs 27.1

8.1. When asked to visit a large file, Emacs now offers to visit it literally.

Previously, Emacs would only ask for confirmation before visiting large files. Now it also offers a third alternative: to visit the file literally, as in find-file-literally, which speeds up navigation and editing of large files.

8.2. zap-to-char now uses the history of characters you used to zap to.

zap-to-char uses the new read-char-from-minibuffer function to allow navigating through the history of characters that have been input. This is mostly useful for characters that have complex input methods where inputting the character again may involve many keystrokes.

8.3. save-some-buffers now has a new action in the prompt: 【C-f】 will

exit the command and switch to the buffer currently being asked about.

8.4. More commands support noncontiguous rectangular regions, namely

upcase-dwim, downcase-dwim, capitalize-dwim, capitalize-region, upcase-initials-region, replace-string, replace-regexp, and delimit-columns-region.

8.5. The new amalgamating-undo-limit variable can be used to control

how many changes should be amalgamated when using the 'undo' command.

8.6. The newline-and-indent command (commonly bound to 'RET' in many

modes) now takes an optional numeric argument to specify how many times is should insert newlines (and indent).

8.7. New command make-empty-file.

8.8. New variable 'x-wait-for-event-timeout'.

This controls how long Emacs will wait for updates to the graphical state to take effect (making a frame visible, for example).

8.9. New user option electric-quote-replace-double.

This option controls whether '"' is replaced in electric-quote-mode, in addition to other quote characters. If non-nil, ASCII double-quote characters that quote text "like this" are replaced by double typographic quotes, “like this”, in text modes, and in comments in non-text modes.

8.10. New user option 「flyspell-case-fold-duplications」.

This option controls whether Flyspell mode considers consecutive words to be duplicates if they are not in the same case. If non-nil, the default, words are considered to be duplicates even if their letters' case does not match.

8.11. write-abbrev-file now includes special properties.

write-abbrev-file now writes special properties like ':case-fixed' for abbrevs that have them.

8.12. write-abbrev-file skips empty tables.

write-abbrev-file now skips inserting a define-abbrev-table form for tables which do not have any non-system abbrevs to save.

8.13. The new functions and commands text-property-search-forward and

text-property-search-backward have been added. These provide an interface that's more like functions like search-forward.

8.14. add-dir-local-variable now uses dotted pair notation syntax to

write alists of variables to ".dir-locals.el". This is the same syntax that you can see in the example of a ".dir-locals.el" file in the node "(emacs) Directory Variables" of the user manual.

8.15. Network connections using 'local' can now use IPv6.

make-network-process now uses the correct loopback address when asked to use ":host 'local" and ":family 'ipv6".

8.16. The new function replace-region-contents replaces the current

region using a given replacement-function in a non-destructive manner (in terms of replace-buffer-contents).

8.17. The command replace-buffer-contents now has two optional

arguments mitigating performance issues when operating on huge buffers.

8.18. Dragging 'C-M-mouse-1' now marks rectangular regions.

8.19. The command delete-indentation now operates on the active region.

If the region is active, the command joins all the lines in the region. When there's no active region, the command works on the current and the previous or the next line, as before.

8.20. You can now change the font size with the mouse wheel.

Scrolling the mouse wheel with the Ctrl key pressed will now act the same as the 'C-x C-+' and 'C-x C–' commands.

9. Changes in Specialized Modes and Packages in Emacs 27.1

9.1. New HTML mode skeleton html-id-anchor.

This new command (which inserts an <a id="foo">_</a> skeleton) is bound to 'C-c C-c #'.

9.2. New command font-lock-debug-fontify.

This is an interactive convenience function to be used when developing font locking for a mode. It recomputes the font locking data and then re-fontifies the buffer.

9.3. Font Lock is smarter about fontifying unterminated strings and comments.

When you type a quote that starts a string, or a comment delimiter that starts a comment, font-lock will not immediately refontify the following characters in font-lock-string-face or font-lock-comment-face. Instead, it will delay the fontification beyond the current line to give you a chance to close the string or comment. This is controlled by the new user option jit-lock-antiblink-grace, which specifies the delay in seconds. The default is 2 seconds; set to nil to get back the old behavior.

9.4. The 'C' command in tar-mode will now preserve the timestamp of

the extracted file if the new user option 「tar-copy-preserve-time」 is non-nil.

9.5. autoconf-mode is now used instead of m4-mode for the

"acinclude.m4" / "aclocal.m4" / "acsite.m4" files.

9.6. On GNU/Linux, 【M-x battery】 will now list all batteries, no matter

what they're named, and the 「battery-linux-sysfs-regexp」 variable has been removed.

9.7. The list-processes command now includes port numbers in the

network connection information (in addition to the host name).

9.8. The 'cl' package is now officially deprecated in favor of 「cl-lib」.

9.9. desktop

9.9.1. When called interactively with a prefix arg 【C-u】, desktop-read

now prompts the user for the directory containing the desktop file.

9.10. display-line-numbers-mode

9.10.1. New faces 「line-number-major-tick」 and 「line-number-minor-tick」,

and user options display-line-numbers-major-tick and display-line-numbers-minor-tick can be used to highlight the line numbers of lines multiple of certain numbers.

9.10.2. New variable display-line-numbers-offset, when non-zero, adds

an offset to absolute line numbers.

9.11. winner

9.11.1. A new user option, 「winner-boring-buffers-regexp」, has been added.

9.12. table

9.12.1. table-generate-source now supports wiki and mediawiki.

This command can now output wiki and mediawiki format tables.

9.13. telnet-mode

9.13.1. Reverting a buffer in 「telnet-mode」 will restart a closed connection.

9.14. goto-addr

9.14.1. A way to more conveniently specify what URI address schemes should

be ignored has been added via the 「goto-address-uri-schemes-ignored」 variable.

9.15. tex-mode

9.15.1. 「latex-noindent-commands」 controls indentation of certain commands.

You can use this new user option to control indentation of arguments of \emph, \footnote, and similar commands.

9.16. byte compiler

9.16.1. byte-compile-dynamic is now obsolete.

This is because on the one hand it suffers from misbehavior in corner cases that have plagued it for years, and on the other hand experience indicates that it doesn't bring any measurable benefit.

9.16.2. The 'g' keystroke in "Compile-Log" buffers has been bound to a

new command that will recompile the file previously compiled with 'M-x byte-compile-file' and the like.

9.17. compile.el

9.17.1. In 「compilation-error-regexp-alist」, 'line' (and 「end-line」) can

be functions.

9.17.2. 「compilation-context-lines」 can now take the value t; this is like

nil, but instead of scrolling the current line to the top of the screen when there is no left fringe, it inserts a visible arrow before column zero.

9.17.3. The new 「compilation-transform-file-match-alist」 user option can

be used to transform file name matches compilation output, and remove known false positives being recognized as warnings/errors.

9.18. cl-lib.el

9.18.1. cl-defstruct has a new ':noinline' argument to prevent inlining

its functions.

9.18.2. cl-defstruct slots accept a ':documentation' property.

9.18.3. cl-values-list will now signal an error if its argument isn't a list.

9.19. doc-view.el

9.19.1. New commands 「doc-view-presentation」 and 「doc-view-fit-window-to-page」.

9.19.2. Added support for password-protected PDF files.

9.19.3. A new user option 「doc-view-pdftotext-program-args」 has been added

to allow controlling how the conversion to text is done.

9.19.4. The prefix key 's' was changed to 'c' for slicing commands

to avoid conflicts with image-mode key 's'. The new key 'c' still has good mnemonics of "cut", "clip", "crop".

9.20. Ido

9.20.1. New user option 「ido-big-directories」 to mark directories whose

names match certain regular expressions as big. Ido won't attempt to list the contents of such directories when completing file names.

9.21. Minibuffer

9.21.1. New user option minibuffer-beginning-of-buffer-movement.

This option allows control of how the 'M-<' command works in the minibuffer. If non-nil, point will move to the end of the prompt (if point is after the end of the prompt). The default is nil, which preserves the original behavior of 'M-<' moving to the beginning of the prompt.

9.21.2. When the minibuffer is active, echo-area messages are displayed at

the end of the minibuffer instead of hiding the minibuffer by the echo area display. The new user option minibuffer-message-clear-timeout controls how messages displayed in this situation are removed from the minibuffer. To revert to previous behavior, where echo-area messages temporarily overwrote the minibuffer contents until the user typed something, set set-message-function and clear-message-function to nil.

9.21.3. Minibuffer now uses minibuffer-message to display error messages

at the end of the active minibuffer. To disable this, remove minibuffer-error-initialize from minibuffer-setup-hook.

9.21.4. 'y-or-n-p' now uses the minibuffer to read 'y' or 'n' answer.

9.21.5. Some commands that previously used read-char-choice now read

a character using the minibuffer by read-char-from-minibuffer.

9.22. map.el

9.22.1. Now also understands plists.

9.22.2. Now defined via generic functions that can be extended via cl-defmethod.

9.22.3. Deprecate the map-put macro in favor of a new 'map-put!' function.

9.22.4. map-contains-key now returns a boolean rather than the key.

9.22.5. Deprecate the 'testfn' args of map-elt and map-contains-key.

9.22.6. New generic function map-insert.

9.22.7. The 'type' arg can be a list '(hash-table :key1 VAL1 :key2 VAL2 …)'.

9.23. seq.el

New convenience functions seq-first and seq-rest give easy access to respectively the first and all but the first elements of sequences.

The new predicate function seq-contains-p should be used instead of the now obsolete seq-contains.

9.24. Follow mode

In the current follow group of windows, "ghost" cursors are no longer displayed in the non-selected follow windows. To get the old behavior back, customize 「follow-hide-ghost-cursors」 to nil.

9.25. New variable 「warning-fill-column」 for display-warning.

9.26. Windmove

9.26.1. 「windmove-create-window」 when non-nil makes a new window.

This happens upon moving off the edge of the frame.

9.26.2. Windmove supports directional window display and selection.

The new command windmove-display-default-keybindings binds default keys with provided modifiers (by default, Shift-Meta) to the commands that display the next buffer in the window at the specified direction. This is like windmove-default-keybindings that binds keys to commands that select the window in the specified direction, but additionally it displays the buffer from the next command in that window. For example, 'S-M-right C-h i' displays the "Info" buffer in the right window, creating the window if necessary. A special key can be customized to display the buffer in the same window, for example, 'S-M-0 C-h e' displays the "Messages" buffer in the same window. 'S-M-t C-h r' displays the Emacs manual in a new tab.

9.26.3. Windmove also supports directional window deletion.

The new command windmove-delete-default-keybindings binds default keys with provided prefix (by default, 【C-x】) and modifiers (by default, 'Shift') to the commands that delete the window in the specified direction. For example, 'C-x S-down' deletes the window below. With a prefix arg 【C-u】, also kills the buffer in that window. With 【M-0】, deletes the selected window and selects the window that was in the specified direction.

9.26.4. New command 「windmove-swap-states-in-direction」 binds default keys

to the commands that swap the states of the selected window with the window in the specified direction.

9.26.5. Windmove code no longer used is now obsolete.

That includes the user option 「windmove-window-distance-delta」 and the functions 「windmove-coord-add」, 「windmove-constrain-to-range」, 「windmove-constrain-around-range」, 「windmove-frame-edges」, 「windmove-constrain-loc-for-movement」, 「windmove-wrap-loc-for-movement」, 「windmove-reference-loc」 and 「windmove-other-window-loc」.

9.27. Octave mode

The mode is automatically enabled in files that start with the 'function' keyword.

9.28. project.el

9.28.1. New commands project-search and project-query-replace-regexp.

9.28.2. New user option 「project-read-file-name-function」.

9.29. Etags

9.29.1. next-file is now an obsolete alias of tags-next-file.

9.29.2. 「tags-loop-revert-buffers」 is an obsolete alias of


9.29.3. The tags-loop-continue function along with the

「tags-loop-operate」 and 「tags-loop-scan」 variables are now obsolete; use the new fileloop-initialize and 「fileloop-continue」 functions instead.

9.29.4. etags is now able to read Zstandard-compressed files.

9.30. bibtex

9.30.1. New commands 「bibtex-next-entry」 and 「bibtex-previous-entry」.

In 「bibtex-mode-map」, forward-paragraph and backward-paragraph are remapped to these, respectively.

9.31. Dired

9.31.1. New command dired-create-empty-file.

9.31.2. New command dired-number-of-marked-files.

It is by default bound to '* N'.

9.31.3. The marking commands now report how many files were marked by the

command itself, not how many files are marked in total.

9.31.4. The new user option dired-create-destination-dirs controls whether

dired-do-copy and dired-rename-file should create non-existent directories in the destination.

9.31.5. dired-dwim-target can be customized to prefer either the next window,

or one of the most recently visited windows with a Dired buffer.

9.31.6. When the new user option dired-vc-rename-file is non-nil,

Dired performs file renaming using underlying version control system.

9.31.7. Zstandard compression is now supported for dired-do-compress and


9.31.8. On systems that support suid/guid files, Dired now fontifies the

permissions of such files with a special face 「dired-set-id」.

9.31.9. A new face, 「dired-special」, is used to highlight sockets, named

pipes, block devices and character devices.

9.32. Find-Dired

9.32.1. New user option 「find-dired-refine-function」.

The default value is 「find-dired-sort-by-filename」.

9.32.2. New sorting options for the user option 「find-ls-option」.

9.33. Change Logs and VC

9.33.1. New user option vc-tor.

When non-nil, this user option causes the VC commands to communicate with the repository via Tor's proxy, using the 'torsocks' wrapper script. The default is nil.

9.33.2. New command 「log-edit-generate-changelog-from-diff」, bound to 'C-c C-w'.

This generates ChangeLog entries from the VC fileset diff.

9.33.3. Recording ChangeLog entries doesn't require an actual file.

If a ChangeLog file doesn't exist, and if the new user option 「add-log-dont-create-changelog-file」 is non-nil (which is the default), commands such as 【C-x 4 a】 will add log entries to a suitable named temporary buffer. (An existing ChangeLog file will still be used if it exists.) Set the user option to nil to get the previous behavior of always creating a buffer that visits a ChangeLog file.

9.33.4. The new 'd' command (「vc-dir-clean-files」) in 「vc-dir-mode」

buffers will delete the marked files (or if no files are marked, the file under point). This command does not notify the VC backend, and is mostly useful for unregistered files.

9.33.5. 「vc-dir-ignore」 now takes a prefix argument to ignore all marked files.

9.33.6. New user option vc-git-grep-template.

This new user option allows customizing the default arguments passed to 「git-grep」 when vc-git-grep is used.

9.33.7. Command vc-git-stash now respects marks in the "vc-dir" buffer.

When some files are marked, only those are stashed. When no files are marked, all modified files are stashed, as before.

9.33.8. vc-dir now shows a button allowing you to hide the stash list.

Controlled by user option vc-git-show-stash. Default t means show the entire list as before. An integer value limits the list length (but still allows you to show the entire list via the button).

9.33.9. vc-git-stash is now bound to 'C' in the stash headers.

9.33.10. Some stash keybindings are now available in the stash button.

vc-git-stash and vc-git-stash-snapshot can now be run using 'C' and 'S' respectively, including when there are no stashes.

9.33.11. The new hook 「vc-retrieve-tag-hook」 runs after retrieving a tag.

9.33.12. 「vc-hg」 now invokes smerge-mode when visiting files.

Code that attempted to invoke smerge-mode when visiting an Hg file with conflicts existed in earlier versions of Emacs, but incorrectly never detected a conflict due to invalid assumptions about cached values.

9.33.13. The Hg (Mercurial) back-end now supports vc-region-history.

The 【C-x v h】 command now works in buffers that visit files controlled by Hg.

9.33.14. The Hg (Mercurial) back-end now prompts for revision to merge when

you invoke 【C-x v m】 (vc-merge).

9.33.15. The Hg (Mercurial) back-end now uses tags, branches and bookmarks

instead of revision numbers as completion candidates when it prompts for a revision.

9.33.16. New user option 「vc-hg-revert-switches」.

It specifies switches to pass to Hg's 'revert' command.

9.33.17. 'C-u C-x v D' (vc-root-version-diff) prompts for two revisions

and compares their entire trees.

9.33.18. 【C-x v M D】 (vc-diff-mergebase) and 【C-x v M L】 (vc-log-mergebase)

print diffs and logs between the merge base (common ancestor) of two given revisions.

9.33.19. New command vc-log-search asks for a pattern, searches it

in the revision log, and displays matched log entries in the log buffer. For example, 'M-x vc-log-search RET bug#36644 RET' displays all entries whose log messages match the bug number. With a prefix argument asks for a command, so for example, 'C-u M-x vc-log-search RET git log -1 f302475 RET' will display just one log entry found by its revision number.

9.33.20. It is now possible to display a specific revision given by its ID.

If you invoke 【C-x v L】 (vc-print-root-log) with a numeric argument of 1, as in 'C-1 C-x v L' or 'C-u 1 C-x v L', it asks for a revision ID, and shows its log entry together with the diffs introduced by the revision's commit. (For some less capable VCSes, only the log entry is shown.)

9.33.21. New user option vc-find-revision-no-save.

With non-nil, vc-find-revision doesn't write the created buffer to file.

9.33.22. 'C-x v =' can now mimic Magit's diff format.

Set the new user option diff-font-lock-prettify to t for that, see below under "Diff mode".

9.33.23. The 'diff' function arguments OLD and NEW may each be a buffer

rather than a file, in non-interactive calls. This change was made in Emacs 24.1, but wasn't documented until now.

9.33.24. New command diff-buffers interactively diffs two buffers.

9.34. Diff mode

9.34.1. Hunks are now automatically refined by font-lock.

To disable refinement, set the new user option diff-refine to nil. To get back the old behavior where hunks are refined as you navigate through a diff, set diff-refine to the symbol 'navigate'.

9.34.2. diff-auto-refine-mode is deprecated in favor of diff-refine.

It is no longer enabled by default and binding it no longer has any effect.

9.34.3. Better syntax highlighting of Diff hunks.

Fragments of source in Diff hunks are now by default highlighted according to the appropriate major mode. Customize the new user option diff-font-lock-syntax to nil to disable this.

9.34.4. File headers can be shortened, mimicking Magit's diff format.

To enable it, set the new user option diff-font-lock-prettify to t. On GUI frames, this option also displays the insertion and deletion indicators on the left fringe.

9.34.5. Prefix arg of diff-goto-source means jump to the old revision

of the file under version control if point is on an old changed line, or to the new revision of the file otherwise.

9.35. Texinfo

9.35.1. New function for inserting '@pxref', '@xref', or '@ref' commands.

The function 'texinfo-insert-dwim-@ref', bound to 'C-c C-c r' by default, inserts one of three types of references based on the text surrounding point, namely '@pxref' near a parenthesis, '@xref' at the start of a sentence or at '(point-min)', else '@ref'.

9.36. Browse-url

9.36.1. The function browse-url-emacs can now visit a URL in selected window.

It now treats the optional 2nd argument to mean that the URL should be shown in the currently selected window.

9.36.2. A new function, browse-url-add-buttons can be used to add clickable

links to most ordinary special-mode buffers that display text that have URLs embedded. browse-url-button-regexp controls what's considered a button.

9.36.3. New user option browse-url-secondary-browser-function.

It can be set to a function that invokes an alternative browser.

9.37. Comint

9.37.1. send-invisible is now an obsolete alias for comint-send-invisible.

Also, shell-strip-ctrl-m is declared obsolete.

9.37.2. 'C-c .' (comint-insert-previous-argument) no longer interprets '&'.

This feature caused problems when '&&' was present in the previous command. Since this command emulates 'M-.' in Bash and zsh, neither of which treats '&' specially, the feature was removed for compatibility with these shells.

9.37.3. comint-insert-previous-argument can now count arguments from the end.

By default, invoking 'C-c .' with a numeric argument N would copy the Nth argument, counting from the first one. But if the new user option comint-insert-previous-argument-from-end is non-nil, it will copy the Nth argument counting from the last one. Thus 'C-c .' can now better emulate 'M-.' in both Bash and zsh, since the former counts from the beginning of the arguments, while the latter counts from the end.

9.37.4. comint-run can now accept a list of switches to pass to the program.

'C-u M-x comint-run' will prompt for the switches interactively.

9.37.5. Abnormal hook comint-password-function has been added.

This hook permits a derived mode to supply a password for the underlying command interpreter without prompting the user. For example, in sql-mode, the password for connecting to the database may be stored in the connection wallet and may be passed on the command line to start the SQL interpreter. This is a potential security flaw that could expose user's database passwords on the command line through the use of a process list (Bug#8427). With this hook, it is possible to not pass the password on the command line and wait for the program to prompt for the password. When it does so, the password can be supplied to the SQL interpreter without involving the user just as if it had been supplied on the command line.

9.38. SQL

9.38.1. SQL Indent Minor Mode

SQL Mode now supports the ELPA 「sql-indent」 package for assisting sophisticated SQL indenting rules. Note, however, that SQL is not like other programming languages like C, Java, or Python where code is sparse and rules for formatting are fairly well established. Instead SQL is more like COBOL (from which it came) and code tends to be very dense and line ending decisions driven by syntax and line length considerations to make readable code. Experienced SQL developers may prefer to rely upon existing Emacs facilities for formatting code but the 「sql-indent」 package provides facilities to aid more casual SQL developers layout queries and complex expressions.

  1. 「sql-use-indent-support」 (default t) enables SQL indentation support.

    The 「sql-indent」 package from ELPA must be installed to get the indentation support in sql-mode and 「sql-interactive-mode」.

  2. 「sql-mode-hook」 and 「sql-interactive-mode-hook」 changed.

    Both hook variables have had 「sql-indent-enable」 added to their default values. If you have existing customizations to these variables, you should make sure that the new default entry is included.

9.38.2. Connection Wallet

Database passwords can now by stored in NETRC or JSON data files that may optionally be encrypted. When establishing an interactive session with the database via sql-connect or a product specific function, like sql-mysql or sql-postgres, the password wallet will be searched for the password. The 「sql-product」, 「sql-server」, 「sql-database」, and the 「sql-username」 will be used to identify the appropriate authorization. This eliminates the discouraged practice of embedding database passwords in your Emacs initialization.

See the 「auth-source」 module for complete documentation on the file formats. By default, the wallet file is expected to be in the user-emacs-directory, named "sql-wallet" or ".sql-wallet", with ".json" (JSON) or no (NETRC) suffix. Both file formats can optionally be encrypted with GPG by adding an additional ".gpg" suffix.

9.39. Term

9.39.1. 「term-read-noecho」 is now obsolete, use read-passwd instead.

9.39.2. serial-term now takes an optional parameter to leave the

emulator in line mode.

9.40. Flymake

9.40.1. The variable 「flymake-diagnostic-types-alist」 is obsolete.

You should instead set properties on known diagnostic symbols, like ':error' and ':warning', as demonstrated in the Flymake manual.

9.40.2. New user option 「flymake-start-on-save-buffer」.

Control whether Flymake starts checking the buffer on save.

9.40.3. Flymake and backend functions may exchange hints about buffer changes.

This enables more efficient backends. See the docstring of 「flymake-diagnostic-functions」 or the Flymake manual for details.

9.40.4. 「flymake-start-syntax-check-on-newline」 is now obsolete,

use post-self-insert-hook to check on newline.

9.41. Ruby

9.41.1. The Rubocop Flymake diagnostic function will only run Lint cops if

it can't find the config file.

9.41.2. Rubocop is called with 'bundle exec' if Gemfile mentions it.

9.41.3. New command 「ruby-find-library-file」 bound to 'C-c C-f'.

9.42. Package

9.42.1. Warn if "footer line" is missing, but still install package.

package.el used to refuse to install a package without the so-called "footer line", which appears at the very end of the file:

;;; FILENAME ends here

package.el will now install packages without this line, but it will issue a warning. To avoid this warning, packages should keep the "footer line".

Note that versions of Emacs older than 27.1 will not only refuse to install packages without such a line – they will be unable to parse package data. It is therefore recommended to keep this line.

9.42.2. Change of package-check-signature for packages with multiple sigs.

In previous Emacsen, t checked that all signatures are valid. Now t only checks that at least one signature is valid and the new 'all' value needs to be used if you want to enforce that all signatures are valid. This only affects packages with multiple signatures.

9.42.3. The meaning of 「allow-unsigned」 in package-check-signature has

changed slightly: If a usable OpenPGP configuration can't be found (for instance, if gpg isn't installed), it now has the same meaning as nil.

9.42.4. New function package-get-version lets packages query their own version.

Example use in auctex.el: '(defconst auctex-version (package-get-version))'

9.42.5. New package-quickstart feature.

When package-quickstart is non-nil, package.el precomputes a big autoloads file so that activation of packages can be done much faster, which can speed up your startup significantly. It also causes user options like package-user-dir and package-load-list to be consulted when package-quickstart-refresh is run rather than at startup so you don't need to set them in your early init file.

9.42.6. New function package-activate-all.

9.42.7. New functions for filtering packages list.

A new function has been added which allows users to filter the packages list by name: package-menu-filter-by-name. By default, it is bound to '/ n'. Additionally, the function package-menu-filter-by-keyword has been renamed from package-menu-filter. Its keybinding has also been changed to '/ k' (from 'f'). To clear any of the two filters, the user can now call the package-menu-clear-filter function, bound to '/ /' by default.

9.42.8. Imenu support has been added to package-menu-mode.

9.42.9. The package list can now be sorted by version or description.

9.42.10. In Package Menu, 'g' now updates package data from archives.

Previously, 'g' invoked tabulated-list-revert which did not update the cached archive data. It is now bound to revert-buffer, which will update the data.

package-menu-refresh is an obsolete alias for revert-buffer.

9.43. Info

9.43.1. Clicking on the left/right arrow icon in the Info tool-bar while

holding down the Ctrl key pops up a menu of previously visited Info nodes where you can select a node to go back (like in browsers).

9.43.2. Info can now follow 'file://' protocol URLs.

The 'file://' URLs in Info documents can now be followed by passing them to the browse-url function, like the other protocols: 'ftp', 'http', and 'https'. This allows having references to local HTML files, for example.

9.44. Display of man pages now limits the width for formatting pages.

The new user option 'Man-width-max' (80 by default) limits the number of columns passed to the 'man' program for formatting man pages. This is to enhance readability when man pages are displayed in very wide windows (which are customary with today's large displays).

9.45. Xref

9.45.1. New command xref-find-definitions-at-mouse.

This command finds definitions of the identifier at the place of a mouse click event, and is intended to be bound to a mouse event.

9.45.2. Changing 「xref-marker-ring-length」 works after xref.el is loaded.

Previously, setting 「xref-marker-ring-length」 would only take effect if set before xref.el was loaded.

9.45.3. xref-find-definitions now sets the mark at the buffer position

where it was invoked.

9.45.4. New xref faces 「xref-file-header」, 「xref-line-number」, 「xref-match」.

9.45.5. New user option 「xref-show-definitions-function」.

It encapsulates the logic pertinent to showing the result of xref-find-definitions. The user can change it to customize its behavior and the display of results.

9.45.6. Search results show the buffer even for one hit.

The search-type Xref commands (e.g. xref-find-references or project-find-regexp) now show the results buffer even when there is only one hit. This can be altered by changing 「xref-show-xrefs-function」.

9.45.7. Xref buffers support refreshing the search results.

A new command 「xref-revert-buffer」 is bound to 'g'.

9.45.8. Imenu support has been added to 'xref–xref-buffer-mode'.

9.45.9. New generic method 「xref-backend-identifier-completion-ignore-case」.

Using it, the etags backend now honors tags-case-fold-search during identifier completion.

9.46. Checkdoc

9.46.1. Checkdoc can now optionally spell-check doc strings.

Invoking 「checkdoc-buffer」 with a non-nil TAKE-NOTES argument (interactively, with a prefix arg) will now spell-check the doc strings and report all the spelling mistakes.

9.47. Icomplete

9.47.1. New minor mode Fido mode.

This mode is based on Icomplete, and its name stands for "Fake Ido". The point of this mode is to be an ido-mode workalike, providing most of the functionality present in ido-mode that is not in Icomplete, which is much more compatible with all of Emacs's completion facilities.

9.48. Ecomplete

9.48.1. The Ecomplete sorting has changed to a decay-based algorithm.

This can be controlled by the new 「ecomplete-sort-predicate」 user option.

9.48.2. The 「ecomplete-database-file」 file is now placed in

"~/.emacs.d/ecompleterc" by default. Of course it will still find it if you have it in "~/.ecompleterc".

9.49. Gnus

9.49.1. 「mm-uu-diff-groups-regexp」 now defaults to matching all groups,

which means that "git am" diffs are recognized everywhere.

9.49.2. Two new Gnus summary mode navigation commands have been added,

bound to the '[' and ']' keys: 「gnus-summary-prev-unseen-article」 and 「gnus-summary-next-unseen-article」. These take you (respectively) to the previous unseen or next unseen article. (These are the ones that are marked with "." in the summary mode lines.)

9.49.3. The Gnus user variable 「nnimap-expunge」 supports three new values:

'never' for never expunging messages, 'immediately' for immediately expunging deleted messages, and 「on-exit」 to expunge deleted articles when exiting the group's summary buffer. Setting 「nnimap-expunge」 to nil or t is still supported but not recommended, since it may result in Gnus expunging all messages that have been flagged as deleted by any IMAP client (rather than just those that have been deleted by Gnus).

9.49.4. New user option 「gnus-use-atomic-windows」 makes Gnus window layouts atomic.

See the "(elisp) Atomic Windows" node of the Elisp manual for details.

9.49.5. There's a new value for 「gnus-article-date-headers」,

「combined-local-lapsed」, which will show both the time (in the local timezone) and the lapsed time.

9.49.6. Gnus now maps imaps to 993 only on old MS-Windows versions.

The nnimap backend used to do this unconditionally to work around problems on old versions of MS-Windows. This is now done only for Windows XP and older.

9.49.7. The nnimap backend now has support for IMAP namespaces.

This feature can be enabled by setting the new 「nnimap-use-namespaces」 server variable to non-nil.

9.49.8. A prefix argument to 「gnus-summary-limit-to-score」 will limit in reverse.

Limit to articles with score "at or below" the SCORE argument rather than "at or above".

9.49.9. The function 「gnus-score-find-favorite-words」 has been renamed

from 「gnus-score-find-favourite-words」.

9.49.10. Gmane has been removed as an nnir backend, since Gmane no longer

has a search engine.

9.49.11. Splitting mail on common mailing list headers has been added.

See the concept index in the Gnus manual for the 「match-list」 entry.

9.49.12. nil is no longer an allowed value for 「mm-text-html-renderer」.

9.49.13. The default value of 「mm-inline-large-images」 has changed from nil

to 'resize', which means that large images will be resized instead of displayed with an external program by default.

9.49.14. A new Gnus summary mode command, 'S A' (「gnus-summary-attach-article」)

can be used to attach the current article(s) to a pre-existing Message buffer, or create a new Message buffer with the article(s) attached.

9.49.15. A new Gnus summary mode command, 'w' (「gnus-summary-browse-url」)

scans the article buffer for URLs, and offers them to the user to open with browse-url.

9.49.16. New user option 「nnir-notmuch-filter-group-names-function」.

This option controls whether and how to use Gnus search groups as 'path:' search terms to 'notmuch'.

9.49.17. The buttons in the Gnus article buffer were formerly widgets

(i.e., buttons from widget.el). This has now changed, and they are now buttons (from button.el), and commands like 'TAB' now search for buttons instead of widgets. There should be no user-visible changes, but out-of-tree code that relied on widgets being present might now fail.

9.50. erc

9.50.1. New hook 「erc-insert-done-hook」.

This hook is called after strings have been inserted into the buffer, and is free to alter point and window configurations, as it's not called from inside a save-excursion, as opposed to 「erc-insert-post-hook」.

9.50.2. 「erc-button-google-url」 has been renamed to 「erc-button-search-url」

and its value has been changed to Duck Duck Go.

9.50.3. 「erc-send-pre-hook」 and 「erc-send-this」 have been obsoleted.

The user option to use instead to alter text to be sent is now 「erc-pre-send-functions」.

9.50.4. Improve matching/highlighting of nicknames.

Open and close parenthesis and apostrophe are not considered valid nick characters anymore, matching the given grammar in RFC 2812 section 2.3.1. This enables correct matching and highlighting of nicks when they are surrounded by parentheses, like "(nick)", and when adjacent to an apostrophe, like "nick's".

9.50.5. Set 「erc-button-url-regexp」 to browse-url-button-regexp

which better handles surrounding pair of parentheses.

9.50.6. New function 「erc-switch-to-buffer-other-window」

which is like 「erc-switch-to-buffer」, but opens the buffer in another window.

9.50.7. New function 「erc-track-switch-buffer-other-window」

which is like 「erc-track-switch-buffer」, but opens the buffer in another window.

9.51. EUDC

9.51.1. XEmacs support has been removed.

9.52. eww/shr

9.52.1. The new user option 「shr-cookie-policy」 can be used to control

when to use cookies when fetching embedded images. The default is to use them when the images are from the same domain as the main HTML document.

9.52.2. The 'eww' command can now create a new EWW buffer.

Invoking the command with a prefix argument will cause it to create a new EWW buffer for the URL instead of reusing the default one.

9.52.3. Clicking with the Ctrl key or 【C-u RET】 on a link opens a new tab

when tab-bar-mode is enabled.

9.52.4. The 'd' (「eww-download」) command now falls back to current page's URL.

If this command is invoked with no URL at point, it now downloads the current page instead of signaling an error.

9.52.5. When opening external links in eww/shr (typically with the

【C-u RET】 keystroke on a link), the link will be flashed with the new 「shr-selected-link」 face to give the user feedback that the command has been executed.

9.52.6. New user option 「shr-discard-aria-hidden」.

If set, shr will not render tags with attribute 'aria-hidden="true"'. This attribute is meant to tell screen readers to ignore a tag.

9.52.7. 「shr-external-browser」 has been made into an obsolete alias

of browse-url-secondary-browser-function.

9.52.8. 「shr-tag-ol」 now respects the ordered list 'start' attribute.

9.52.9. The following tags are now handled: '<code>', '<abbr>', and '<acronym>'.

9.53. Htmlfontify

9.53.1. The functions 「hfy-color」, 「hfy-color-vals」 and

hfy-fallback-color-values and the variables 「hfy-fallback-color-map」 and 「hfy-rgb-txt-color-map」 have been renamed from names that used 'colour' instead of 'color'.

9.54. Enriched mode supports the 'charset' text property.

You can add or modify the 'charset' text properties of text using the 'Edit->Text Properties->Special Properties' menu, or by invoking the facemenu-set-charset command. Documents in Enriched mode will be saved with the charset properties, and those properties will be restored when the file is visited.

9.55. Smtpmail

9.55.1. Authentication mechanisms can be added via external packages, by

defining new cl-defmethod of 「smtpmail-try-auth-method」.

9.55.2. To always force smtpmail to send credentials over on the first

attempt when communicating with the SMTP server(s), the 「smtpmail-servers-requiring-authorization」 user option can be used.

9.55.3. smtpmail will now try resending mail when getting a transient "4xx"

error message from the SMTP server. The new 「smtpmail-retries」 user option says how many times to retry.

9.56. Footnote mode

9.56.1. Support Hebrew-style footnotes.

9.56.2. Footnote text lines are now aligned.

Can be controlled via the new user option 「footnote-align-to-fn-text」.

9.57. CSS mode

9.57.1. A new command 「css-cycle-color-format」 for cycling between color

formats (e.g. "black" => "#000000" => "rgb(0, 0, 0)") has been added, bound to 'C-c C-f'.

9.57.2. CSS mode, SCSS mode, and Less CSS mode now have support for Imenu.

9.58. SGML mode

9.58.1. sgml-quote now handles double quotes and apostrophes

when escaping text and in addition all numeric entities when unescaping text.

9.59. Python mode

9.59.1. Python mode supports three different font lock decoration levels.

The maximum level is used by default; customize font-lock-maximum-decoration to tone down the decoration.

9.59.2. New user option 「python-pdbtrack-kill-buffers」.

If non-nil, the default, buffers opened during pdbtracking session are killed when pdbtracking session is finished.

9.59.3. New function 'python-shell-send-statement.

It sends the statement delimited by 「python-nav-beginning-of-statement」 and 「python-nav-end-of-statement」 to the inferior Python process.

9.60. Help

9.60.1. Descriptions of variables and functions give an estimated first release

where the variable or function appeared in Emacs.

9.60.2. Output format of 【C-h l】 (view-lossage) has changed.

For convenience, view-lossage now displays the last keystrokes and commands in the same format as the edit buffer of edit-last-kbd-macro. This makes it possible to copy the lines from the buffer generated by view-lossage to the "Edit Macro" buffer created by edit-last-kbd-macro, and to save the macro by 'C-c C-c'.

9.60.3. The list of help commands produced by 'C-h C-h' (help-for-help)

can now be searched via 【C-s】.

9.61. Ibuffer

9.61.1. New filter 「ibuffer-filter-by-process」; bound to '/ E'.

9.61.2. All mode filters can now accept a list of symbols.

This means you can now easily filter several major modes, as well as a single mode.

9.62. Search and Replace

9.62.1. Isearch supports a prefix argument for 【C-s】 (isearch-repeat-forward)

and 【C-r】 (isearch-repeat-backward). With a prefix argument, these commands repeat the search for the specified occurrence of the search string. A negative argument repeats the search in the opposite direction. This makes possible also to use a prefix argument for 'M-s .' (isearch-forward-symbol-at-point) to find the next Nth symbol. Also a prefix argument is supported for isearch-yank-until-char, isearch-yank-word-or-char, isearch-yank-symbol-or-char.

9.62.2. To go to the first/last occurrence of the current search string

is possible now with new commands isearch-beginning-of-buffer and isearch-end-of-buffer bound to 'M-s M-<' and 'M-s M->' in Isearch. With a numeric argument, they go to the Nth absolute occurrence counting from the beginning/end of the buffer. This complements 【C-s】/【C-r】 that searches for the next Nth relative occurrence with a numeric argument.

9.62.3. isearch-lazy-count shows the current match number and total number

of matches in the Isearch prompt. User options lazy-count-prefix-format and lazy-count-suffix-format define the format of the current and the total number of matches in the prompt's prefix and suffix, respectively.

9.62.4. lazy-highlight-buffer highlights matches in the full buffer.

It is useful in combination with lazy-highlight-cleanup customized to nil to leave matches highlighted in the whole buffer after exiting isearch. Also when lazy-highlight-buffer prepares highlighting in the buffer, navigation through the matches without flickering is more smooth. lazy-highlight-buffer-max-at-a-time controls the number of matches to highlight in one iteration while processing the full buffer.

9.62.5. New isearch bindings.

'C-M-z' invokes new function isearch-yank-until-char, which yanks everything from point up to but not including the specified character into the search string. This is especially useful for keyboard macros.

'C-M-w' in isearch changed from isearch-del-char to the new function isearch-yank-symbol-or-char. isearch-del-char is now bound to 'C-M-d'.

【M-s h l】 invokes highlight-lines-matching-regexp using the search string to highlight lines matching the search string. This is similar to the existing binding 【M-s h r】 (highlight-regexp) that highlights JUST the search string.

9.62.6. New user option isearch-yank-on-move provides options t and 'shift'

to extend the search string by yanking text that ends at the new position after moving point in the current buffer. 'shift' extends the search string by motion commands while holding down the shift key.

9.62.7. isearch-allow-scroll provides a new option 'unlimited' to allow

scrolling any distance off screen.

9.62.8. Isearch now remembers the regexp-based search mode for words/symbols

and case-sensitivity together with search strings in the search ring.

9.62.9. Isearch now has its own tool-bar and menu-bar menu.

9.62.10. flush-lines prints and returns the number of deleted matching lines.

9.62.11. char-fold-to-regexp now matches more variants of a base character.

The table used to check for equivalence of characters is now built using the complete chain of unicode decompositions of a character, rather than stopping after one level, such that searching for e.g. "GREEK SMALL LETTER IOTA" will now also find "GREEK SMALL LETTER IOTA WITH OXIA".

9.62.12. New char-folding options: 「char-fold-include」 lets you add ad hoc

foldings, 「char-fold-exclude」 to remove foldings from default decomposition, and 「char-fold-symmetric」 to search for any of an equivalence class of characters. For example, with a nil value of 「char-fold-symmetric」 you can search for "e" to find "é", but not vice versa. With a non-nil value you can search for either, for example, you can search for "é" to find "e".

9.63. Debugger

9.63.1. The Lisp Debugger is now based on 「backtrace-mode」.

Backtrace mode adds fontification and commands for changing the appearance of backtrace frames. See the node "(elisp) Backtraces" in the Elisp manual for documentation of the new mode and its commands.

9.64. Edebug

9.64.1. 「edebug-eval-last-sexp」 and 「edebug-eval-print-last-sexp」 interactively

now take a zero prefix analogously to the non-Edebug counterparts.

9.64.2. New faces 「edebug-enabled-breakpoint」 and 「edebug-disabled-breakpoint」.

When setting breakpoints in Edebug, an overlay with these faces are placed over the point in question, depending on whether they are enabled or not.

9.64.3. New command 「edebug-toggle-disable-breakpoint」.

This command allows you to disable a breakpoint temporarily. This is mainly useful with breakpoints that are conditional and would take some time to recreate.

9.64.4. New command 「edebug-unset-breakpoints」.

To clear all breakpoints in the current form, the 'U' command in 「edebug-mode」, or 'M-x edebug-unset-breakpoints' can be used.

9.64.5. Re-instrumenting a function with Edebug will now try to preserve

previously-set breakpoints. However, if the code has changed substantially, this may not be possible.

9.64.6. New command 「edebug-remove-instrumentation」.

This command removes Edebug instrumentation from all functions that have been instrumented.

9.64.7. The runtime behavior of Edebug's instrumentation can be changed

using the new variables 「edebug-behavior-alist」, 「edebug-after-instrumentation-function」 and 「edebug-new-definition-function」. Edebug's behavior can be changed globally or for individual definitions.

9.64.8. Edebug's backtrace buffer now uses 「backtrace-mode」.

Backtrace mode adds fontification, links and commands for changing the appearance of backtrace frames. See the node "(elisp) Backtraces" in the Elisp manual for documentation of the new mode and its commands.

The binding of 'd' in Edebug's keymap is now 「edebug-pop-to-backtrace」 which replaces 「edebug-backtrace」. Consequently Edebug's backtrace windows now behave like those of the Lisp Debugger and of ERT, in that when they appear they will be the selected window.

The new 「backtrace-goto-source」 command, bound to 's', works in Edebug's backtraces on backtrace frames whose source code has been instrumented by Edebug.

9.65. Enhanced xterm support

9.65.1. New user option 「xterm-set-window-title」 controls whether Emacs sets

the XTerm window title. This feature is experimental and is disabled by default.

9.66. Grep

9.66.1. 'rgrep', 'lgrep' and 'zrgrep' now hide part of the command line

that contains a list of ignored directories and files. Clicking on the button with ellipsis unhides it. The abbreviation can be disabled by the new user option 「grep-find-abbreviate」. The new command 「grep-find-toggle-abbreviation」 toggles it interactively.

9.66.2. grep-find-use-xargs is now customizable with sorting options.

9.67. ERT

9.67.1. New variable 「ert-quiet」 allows making ERT output in batch mode

less verbose by removing non-essential information.

9.67.2. ERT's backtrace buffer now uses 「backtrace-mode」.

Backtrace mode adds fontification and commands for changing the appearance of backtrace frames. See the node "(elisp) Backtraces" in the Elisp manual for documentation of the new mode and its commands.

9.68. Gamegrid

9.68.1. Gamegrid now determines its default glyph size based on display

dimensions, instead of always using 16 pixels. As a result, Tetris, Snake and Pong are better playable on HiDPI displays.

9.68.2. 「gamegrid-add-score」 can now sort scores from lower to higher.

This is useful for games where lower scores are better, like time-based games.

9.69. Filecache

9.69.1. Completing file names in the minibuffer via 【C-TAB】 now uses the

styles as configured by the user option completion-styles.

9.70. New macros 「thunk-let」 and 'thunk-let*'.

These macros are analogue to 'let' and 'let*', but create bindings that are evaluated lazily.

9.71. next-error

9.71.1. New user option next-error-find-buffer-function.

The value should be a function that determines how to find the next buffer to be used by next-error and previous-error. The default is to use the last buffer that navigated to the current error.

9.71.2. New command next-error-select-buffer.

It can be used to set any buffer as the next one to be used by next-error and previous-error.

9.72. nxml-mode

9.72.1. The default value of nxml-sexp-element-flag is now t.

This means that pressing 'C-M-SPACE' now selects the entire tree by default, and not just the opening element.

9.73. Eshell

9.73.1. TAB completion uses the standard completion-at-point rather than

'pcomplete'. Its UI is slightly different but can be customized to behave similarly, e.g. Pcomplete's default cycling can be obtained with '(setq completion-cycle-threshold 5)'.

9.73.2. Expansion of history event designators is disabled by default.

To restore the old behavior, use

(add-hook 'eshell-expand-input-functions #'eshell-expand-history-references)

9.73.3. The function 「eshell-uniquify-list」 has been renamed from


9.73.4. The function 'eshell/kill' is now able to handle signal switches.

Previously 'eshell/kill' would fail if provided a kill signal to send to the process. It now accepts signals specified either by name or by its number.

9.73.5. Emacs now follows symlinks in history-related files.

The files specified by 「eshell-history-file-name」 and 「eshell-last-dir-ring-file-name」 can include symlinks; these are now followed when Emacs writes the relevant history variables to the disk.

9.74. Shell

9.74.1. Program name completion inside remote shells works now as expected.

9.74.2. The user option shell-file-name can be set now as connection-local

variable for remote shells. It still defaults to "/bin/sh".

9.75. Single shell commands

9.75.1. New values of shell-command-dont-erase-buffer.

This user option can now have the value 'erase' to force to erase the output buffer before execution of the command, even if the output goes to the current buffer. Additional values 「beg-last-out」, 「end-last-out」, and 「save-point」 control where to put point in the output buffer after inserting the shell-command output.

9.75.2. The new functions shell-command-save-pos-or-erase and

shell-command-set-point-after-cmd control how point is handled between two consecutive shell commands in the same output buffer.

9.75.3. async-shell-command-width defines the number of display columns

available for output of asynchronous shell commands.

9.75.4. Prompt for shell commands can now show the current directory.

Customize the new user option shell-command-prompt-show-cwd to enable it.

9.76. Pcomplete

9.76.1. The 'pcomplete' command is now obsolete.

The Pcomplete functionality can be obtained via completion-at-point instead, by adding 「pcomplete-completions-at-point」 to completion-at-point-functions.

9.76.2. The function 「pcomplete-uniquify-list」 has been renamed from


9.76.3. 'pcomplete/make' now completes on targets in included files, recursively.

To recover the previous behavior, set new user option 「pcmpl-gnu-makefile-includes」 to nil.

9.77. Auth-source

9.77.1. The Secret Service backend supports the ':create' key now.

9.77.2. ".authinfo" and ".netrc" files now use a new mode: authinfo-mode.

This is just like fundamental-mode, except that it hides passwords under a "**" display property. When the cursor moves to this text, the real password is revealed (via reveal-mode). The new authinfo-hidden user option can be used to control what to hide.

9.78. Tramp

9.78.1. New connection method "nextcloud", which allows accessing OwnCloud

or NextCloud hosted files and directories.

9.78.2. New connection method "rclone", which allows accessing system

storages via the 'rclone' program. This feature is experimental.

9.78.3. New connection method "sudoedit", which allows editing local files

with different user credentials. Contrary to the "sudo" method, no session is run permanently in the background. This is for security reasons.

9.78.4. Connection methods "obex" and "synce" have been removed, because they

are obsoleted in GVFS.

9.78.5. Validated passwords are saved by auth-source backends which support this.

9.78.6. During user and host name completion in the minibuffer, results

from auth-source search are taken into account. This can be disabled by setting the user option 「tramp-completion-use-auth-sources」 to nil.

9.78.7. The user option tramp-ignored-file-name-regexp allows disabling

Tramp for some look-alike remote file names.

9.78.8. For some connection methods, like "su" or "sudo", the host name in

multi-hop file names must match the previous hop. Default host names are adjusted to the host name from the previous hop.

9.78.9. A timeout has been added for the connection methods "sudo" and "doas".

The underlying session is disabled when the timeout expires. This is for security reasons.

9.78.10. For some connection methods, like "sshx" or "plink", it is

possible to configure the remote login shell. This avoids problems with remote hosts, where "/bin/sh" is a link to a shell which cooperates badly with Tramp.

9.78.11. New commands 「tramp-rename-files」 and 「tramp-rename-these-files」.

They allow saving remote files somewhere else when the corresponding host is not reachable anymore.

9.79. Rcirc

9.79.1. New user option 「rcirc-url-max-length」.

Setting this option to an integer causes URLs displayed in Rcirc buffers to be truncated to that many characters.

9.79.2. The default '/quit' and '/part' reasons are now configurable.

Two new user options are provided for this: 「rcirc-default-part-reason」 and 「rcirc-default-quit-reason」.

9.80. Register

9.80.1. The return value of method register-val-describe includes the

names of buffers shown by the windows of a window configuration.

9.81. Message

9.81.1. Completion of email addresses can use the standard completion UI.

This is controlled by 「message-expand-name-standard-ui」. With the standard UI the different sources (ecomplete, bbdb, and eudc) are matched together and try to obey completion-styles. It should work for other completion front ends like Company.

9.81.2. message-mode now supports highlighting citations of different depths.

This can be customized via the new user option 「message-cite-level-function」 and the new 'message-cited-text-*' faces.

9.81.3. Messages can now be systematically encrypted

when the PGP keyring contains a public key for every recipient. To achieve this, add 「message-sign-encrypt-if-all-keys-available」 to 「message-send-hook」.

9.81.4. When replying a message that have addresses on the form

'"foo@bar.com" <foo@bar.com>', Message will elide the repeated "name" from the address field in the response.

9.81.5. The default of 「message-forward-as-mime」 has changed from t to nil

as it has been reported that many recipients can't read forwards that are formatted as MIME digests.

9.81.6. 「message-forward-included-headers」 has changed its default to

exclude most headers when forwarding.

9.81.7. 「mml-secure-openpgp-sign-with-sender」 sets also "gpg –sender".

When 「mml-secure-openpgp-sign-with-sender」 is non-nil, message sender's email address (in addition to its old behavior) will also be used to set gpg's "–sender email@domain" option.

The option is useful for two reasons when verifying the signature:

  1. GnuPG's TOFU statistics are updated for the specific user id (email) only. See gpg(1) man page about "–sender".
  2. GnuPG's "–auto-key-retrieve" functionality can use WKD (web key directory) method for finding the signer's key. You need GnuPG 2.2.17 to fully benefit from this feature. See gpg(1) man page for "–auto-key-retrieve".

9.81.8. The mail-from-style variable is now obsolete.

According to RFC 5322, only the 'angles' value is valid.

9.82. EasyPG

9.82.1. 「epa-pinentry-mode」 is renamed to 「epg-pinentry-mode」.

It now applies to epg functions as well as epa functions.

9.82.2. The alias functions 'epa–encode-coding-string',

'epa–decode-coding-string', and 'epa–select-safe-coding-system' have been removed. Use encode-coding-string, decode-coding-string, and select-safe-coding-system instead.

9.82.3. 「epg-context」 structure supports now 'sender' slot.

The value of the new 'sender' slot (if a string) is used to set gpg's "–sender" option. This feature is used by 「mml-secure-openpgp-sign-with-sender」. See gpg(1) manual page about "–sender" for more information.

9.82.4. epg-find-configuration no longer finds GnuPG 2.0 through 2.1.5.

Previously, it found these versions by mistake. The intent was to find GnuPG 2.1.6 or later, or find GnuPG 1.4.3 or later within the GnuPG 1 series.

9.83. Rmail

9.83.1. New user option 「rmail-output-reset-deleted-flag」.

If this option is non-nil, messages appended to an output file by the rmail-output command have their Deleted flag reset.

9.83.2. The command rmail-summary-by-senders with an empty argument

selects the messages to summarize with a regexp that matches the sender of the current message.

9.84. Threads

9.84.1. New variable main-thread holds Emacs's main thread.

This is handy in Lisp programs that run on a non-main thread and want to signal the main thread, e.g., when they encounter an error.

9.84.2. thread-join now returns the result of the finished thread.

9.84.3. thread-signal does not propagate errors to the main thread.

Instead, error messages are just printed in the main thread.

9.84.4. 「thread-alive-p」 is now obsolete, use thread-live-p instead.

9.84.5. New command list-threads shows Lisp threads.

See the current list of live threads in a tabulated-list buffer which automatically updates. In the buffer, you can use 's q' or 's e' to signal a thread with quit or error respectively, or get a snapshot backtrace with 'b'.

9.85. thingatpt.el

9.85.1. thing-at-point supports a new "thing" called 'uuid'.

A symbol 'uuid' can be passed to thing-at-point and it returns the UUID at point.

9.85.2. number-at-point will now recognize hex numbers like 0xAb09 and #xAb09

and return them as numbers.

9.85.3. word-at-point and sentence-at-point accept NO-PROPERTIES.

Just like thing-at-point itself.

9.86. Interactive automatic highlighting

9.86.1. highlight-regexp can now highlight subexpressions.

The new command accepts a prefix numeric argument to choose the subexpression.

9.87. Mouse display of minor mode menu

9.87.1. minor-mode-menu-from-indicator now displays full minor mode name.

When there is no menu for a mode, display the mode name after the indicator instead of just the indicator (which is sometimes cryptic).

9.88. rx

9.88.1. rx now handles raw bytes in character alternatives correctly,

when given in a string. Previously, '(any "\x80-\xff")' would match characters U+0080…U+00FF. Now the expression matches raw bytes in the 128…255 range, as expected.

9.88.2. The rx 'or' and 'seq' forms no longer require any arguments.

'(or)' produces a regexp that never matches anything, while '(seq)' matches the empty string, each being an identity for the operation. This also works for their aliases: '|' for 'or'; ':', 'and' and 'sequence' for 'seq'. The symbol 'unmatchable' can be used as an alternative to '(or)'.

9.88.3. 'regexp' and new 'literal' accept arbitrary lisp as arguments.

In this case, 'rx' will generate code which produces a regexp string at run time, instead of a constant string.

9.88.4. New rx extension mechanism: rx-define, rx-let, rx-let-eval.

These macros add new forms to the rx notation.

9.88.5. 'anychar' is now an alias for 'anything'.

Both match any single character; 'anychar' is more descriptive.

9.88.6. New 'intersection' form for character sets.

With 'or' and 'not', it can be used to compose character-matching expressions from simpler parts.

9.88.7. 'not' now accepts more argument types.

The argument can now also be a character, a single-character string, an 'intersection' form, or an 'or' form whose arguments each match a single character.

9.88.8. Nested 'or' forms of strings guarantee a longest match.

For example, '(or (or "IN" "OUT") (or "INPUT" "OUTPUT"))' now matches the whole string "INPUT" if present, not just "IN". Previously, this was only guaranteed inside a single 'or' form of string literals.

9.89. Frames

9.89.1. New command make-frame-on-monitor makes a frame on the specified monitor.

9.89.2. New value of 'minibuffer' frame parameter 「child-frame」.

This allows creating and immediately parenting a minibuffer-only child frame when making a frame.

9.89.3. New predicates display-blink-cursor-p and display-symbol-keys-p.

These predicates are to be preferred over display-graphic-p when testing for blinking cursor capability and the capability to have symbols (e.g., '[return]', '[tab]', '[backspace]') as keys respectively.

9.90. Tabulated List mode

9.90.1. New user options for tabulated list sort indicators.

You can now customize which sorting indicator character to display near the current column in Tabulated Lists (see user options tabulated-list-gui-sort-indicator-asc, tabulated-list-gui-sort-indicator-desc, tabulated-list-tty-sort-indicator-asc, and tabulated-list-tty-sort-indicator-desc).

9.90.2. Two new commands and keystrokes have been added to the tabulated

list mode: 'w' (which widens the current column) and 'c' which makes the current column contract.

9.90.3. New function tabulated-list-clear-all-tags.

This function clears all tags from the padding area in the current buffer. Tags are typically added by calling tabulated-list-put-tag.

9.91. Text mode

9.91.1. text-mode-variant is now obsolete, use derived-mode-p instead.

9.92. CUA mode

9.92.1. New user option 「cua-rectangle-terminal-modifier-key」.

This user option allows for the customization of the modifier key used in a terminal frame.

9.93. JS mode

9.93.1. JSX syntax is now automatically detected and enabled.

If a file imports Facebook's 'React' library, or if the file uses the extension ".jsx", then various features supporting XML-like syntax will be supported in js-mode and derivative modes. (js-jsx-mode no longer needs to be enabled.)

9.93.2. New user option js-jsx-detect-syntax disables automatic detection.

This is turned on by default.

9.93.3. New user option js-jsx-syntax enables JSX syntax unconditionally.

This is off by default.

9.93.4. New variable js-jsx-regexps controls JSX detection.

9.93.5. JSX syntax is now highlighted like SGML.

9.93.6. JSX code is properly indented in many more scenarios.

Previously, JSX indentation usually only worked when an element was wrapped in parenthesis (e.g. in a 'return' statement or a function call). It would also fail in many intricate cases. Now, indentation should work anywhere without parenthesis; many more intricacies are supported; and, indentation conventions align more closely with those of the React developer community (see 'js-jsx-align->-with-<'), otherwise still adhering to SGML conventions.

9.93.7. New user option 'js-jsx-align->-with-<' controls '>' indents.

Commonly in JSX code, a '>' on its own line is indented at the same level as its opening '<'. This is the new default for JSX. This behavior is slightly different than that used by SGML in Emacs, where '>' is indented at the same level as attributes, which was also the old default for JSX.

This is turned on by default. To get back the old default indentation behavior of aligning '>' with attributes, set 'js-jsx-align->-with-<' to nil.

9.93.8. Indentation uses js-indent-level instead of sgml-basic-offset.

Since JSX is a syntax extension of JavaScript, it makes the most sense for JSX expressions to be indented the same number of spaces as other JS expressions. This is a breaking change, but it probably aligns with how you'd expect this indentation to behave. If you want JSX to be indented like JS, you won't need to change your config.

The old behavior can be emulated by controlling JSX indentation independently of JS, by setting js-jsx-indent-level.

9.93.9. New user option js-jsx-indent-level for different JSX indentation.

If you wish to indent JSX by a different number of spaces than JS, set this user option to the desired number.

9.93.10. New user option js-jsx-attribute-offset for JSX attribute indents.

9.93.11. New variable js-syntactic-mode-name controls mode name display.

Previously, the mode name was simply 'JavaScript'. Now, when a syntax extension like JSX is enabled, the mode name is 'JavaScript[JSX]'. Set this variable to nil to disable the new behavior.

9.93.12. New function js-use-syntactic-mode-name for deriving modes.

Packages deriving from js-mode with define-derived-mode should call this function to add enabled syntax extensions to their mode name, too.

9.94. Autorevert

9.94.1. New user option auto-revert-avoid-polling for saving power.

When set to a non-nil value, buffers in Auto Revert mode are no longer polled for changes periodically. This reduces the power consumption of an idle Emacs, but may fail on some network file systems; set auto-revert-notify-exclude-dir-regexp to match files where notification is not supported. The default value is nil.

9.94.2. New variable buffer-auto-revert-by-notification.

A major mode can declare that notification on the buffer's default directory is sufficient to know when updates are required, by setting the new variable buffer-auto-revert-by-notification to a non-nil value. Auto Revert mode can use this information to avoid polling the buffer periodically when auto-revert-avoid-polling is non-nil.

9.94.3. global-auto-revert-ignore-buffer can now also be a predicate

function that can be used for more fine-grained control of which buffers to auto-revert.

9.95. auth-source-pass

9.95.1. New user option 「auth-source-pass-filename」.

Allows setting the path to the password-store, defaults to "~/.password-store".

9.95.2. New user option 「auth-source-pass-port-separator」.

Specifies separator between host and port, defaults to colon ":".

9.95.3. Minimize the number of decryptions during password lookup.

This makes the package usable with physical tokens requiring touching a sensor for every decryption.

9.95.4. auth-source-pass-get is now autoloaded.


9.96.1. bookmark-file and bookmark-old-default-file are now obsolete

aliases of bookmark-default-file.

9.96.2. New user option bookmark-watch-bookmark-file.

When non-nil, watch whether the bookmark file has changed on disk.

9.96.3. The old bookmark file format is no longer supported.

This bookmark file format has not been used in Emacs since at least version 19.34, released in 1996, and will no longer be automatically converted to the new bookmark file format.

The following functions are now declared obsolete: bookmark-grok-file-format-version, bookmark-maybe-upgrade-file-format, bookmark-upgrade-file-format-from-0, and bookmark-upgrade-version-0-alist.

9.97. The mantemp.el library is now marked obsolete.

This library generates manual C++ template instantiations. It should no longer be useful on modern compilers, which do this automatically.

9.98. Ispell

9.98.1. New hook 「ispell-change-dictionary-hook」.

This runs after changing the dictionary and could be used to automatically spellcheck a buffer when changing language without needing to advice ispell-change-dictionary.

9.99. scroll-lock

9.99.1. New command 「scroll-lock-next-line-always-scroll」.

This command is bound to 「S-down」 and scrolls the buffer up in particular when the end of the buffer is visible in the window.

9.100. mwheel.el

9.100.1. mwheel-install is now obsolete.

Use mouse-wheel-mode instead. Note that mouse-wheel-mode is already enabled by default on most graphical displays.

9.101. Gravatar

9.101.1. 「gravatar-cache-ttl」 is now a number of seconds.

The previously used timestamp format of a list of integers is still supported, but is deprecated. The default value has not changed.

9.101.2. 「gravatar-size」 can now be nil.

This results in the use of Gravatar's default size of 80 pixels.

9.101.3. The default fallback gravatar is now configurable.

This is possible using the new user options 「gravatar-default-image」 and 「gravatar-force-default」.

9.102. ada-mode

9.102.1. The built-in ada-mode is now deleted. The GNU ELPA package is a

good replacement, even in very large source files.

9.103. time-stamp

9.103.1. New '%5z' conversion for 「time-stamp-format」 gives time zone offset.

Specifying '%5z' in 「time-stamp-format」 or 「time-stamp-pattern」 expands to the time zone offset, e.g., '+0100'. The time zone used is specified by 「time-stamp-time-zone」.

Because this feature is new in Emacs 27.1, do not use it in the local variables section of any file that might be edited by an older version of Emacs.

9.103.2. Some conversions recommended for 「time-stamp-format」 have changed.

The new documented/recommended %-conversions are closer to those used by format-time-string and are compatible at least as far back as Emacs 22.1 (released in 2007).

Uppercase abbreviated day name of week: was %3A, now %#a Full day name of week: was %:a, now %:A Uppercase abbreviated month name: was %3B, now %#b Full month name: was %:b, now %:B Four-digit year: was %:y, now %Y Lowercase timezone name: was %z, now %#Z Fully-qualified host name: was %s, now %Q Unqualified host name: (was none), now %q Login name: was %u, now %l User's full name: was %U, now %L

Merely having '(add-hook 'before-save-hook #'time-stamp)' in your Emacs init file does not expose you to this change. However, if you set 「time-stamp-format」 or 「time-stamp-pattern」 with a file-local variable, you may need to update the value.

9.104. mode-local

9.104.1. Declare 「define-overload」 and 「define-child-mode」 as obsolete.

9.104.2. Rename several internal functions to use a 'mode-local-' prefix.

9.105. CC Mode

9.105.1. You can now flag "wrong style" comments with font-lock-warning-face.

To do this, use 'c-toggle-comment-style', if needed, to set the desired default comment style (block or line); then set the user option 'c-mark-wrong-style-of-comment' to non-nil.

9.106. Mailcap

9.106.1. The new function mailcap-file-name-to-mime-type has been added.

It's a simple convenience function for looking up MIME types based on file name extensions.

9.106.2. The default way the list of possible external viewers for MIME

types is sorted and chosen has changed. Earlier, the most specific viewer was chosen, even if there was a general override in "~/.mailcap". For instance, if "etc/mailcap" has an entry for "image/gif", that one will be chosen even if you have an entry for "image/*" in your "~.mailcap" file. But with the new method, entries from "~/.mailcap" overrides all system and Emacs-provided defaults. To get the old method back, set mailcap-prefer-mailcap-viewers to nil.

9.107. MH-E

9.107.1. The hook 「mh-show-mode-hook」 is now called before the message is inserted.

Functions that want to affect the message text (e.g. to change highlighting) can no longer use 「mh-show-mode-hook」, because the message contents will not yet have been inserted when the hook is called. Such functions should now be attached to 「mh-show-hook」.

9.108. URL

9.108.1. The 'file:' handler no longer looks for "index.html" in

directories if you ask it for a "file:///dir" URL. Since this is a low-level library, such decisions (if they are to be made at all) are left to higher-level functions.

10. New Modes and Packages in Emacs 27.1

10.1. Tab Bars

10.1.1. Tab Bar mode

The new command tab-bar-mode enables the tab bar at the top of each frame (including TTY frames), where you can use tabs to switch between named persistent window configurations.

The 【C-x t】 sequence is the new prefix key for tab-related commands: 【C-x t 2】 creates a new tab; 【C-x t 0】 deletes the current tab; 【C-x t b】 switches to buffer in another tab; 【C-x t f】 and 'C-x t C-f' edit file in another tab; and 【C-TAB】 and 'S-C-TAB' switch to the next or previous tab. You can also switch between tabs and create/delete tabs with a mouse.

Tab-related commands are available even when tab-bar-mode is disabled: by default, they enable tab-bar-mode in that case.

The X resource "tabBar", class "TabBar" enables the tab bar when its value is "on", "yes" or "1".

The user option tab-bar-position specifies where to show the tab bar.

Tab-related commands can be used even without the tab bar when tab-bar-mode is disabled by a nil value of the user option tab-bar-show. Without the tab bar you can switch between tabs using completion on tab names, or using tab-switcher.

Read the new Info node "(emacs) Tab Bars" for full description of all related features.

10.1.2. Tab Line mode

The new command global-tab-line-mode enables the tab line above each window, which you can use to switch buffers in the window. Selecting the previous window-local tab is the same as typing 'C-x <LEFT>' (previous-buffer), selecting the next tab is the same as 'C-x <RIGHT>' (next-buffer). Both commands support a numeric prefix argument as a repeat count. Clicking on the plus icon adds a new buffer to the window-local tab line of buffers. Using the mouse wheel on the tab line scrolls tabs.

Read the new Info node "(emacs) Tab Line" for full description of all related features.

10.2. fileloop.el lets one setup multifile operations like search&replace.

10.3. Emacs can now visit files in archives as if they were directories.

This feature uses Tramp and works only on systems which support GVFS, i.e. GNU/Linux, roughly spoken. See the node "(tramp) Archive file names" in the Tramp manual for full documentation of these facilities.

10.4. New library for writing JSONRPC applications (https://jsonrpc.org).

The 'jsonrpc' library enables writing Emacs Lisp applications that rely on this protocol. Since the protocol is designed to be transport-agnostic, the library provides an API to implement new transport strategies as well as a separate API to use them. A transport implementation for process-based communication, such as is used by the Language Server Protocol (LSP), is readily available.

10.5. Backtrace mode improves viewing of Elisp backtraces.

Backtrace mode adds pretty printing, fontification and ellipsis expansion to backtrace buffers produced by the Lisp debugger, Edebug and ERT. See the node "(elisp) Backtraces" in the Elisp manual for documentation of the new mode and its commands.

10.6. so-long helps to mitigate performance problems with long lines.

When global-so-long-mode has been enabled, visiting a file with very long lines will (subject to configuration) cause the user's preferred 「so-long-action」 to be automatically invoked (by default, the buffer's major mode is replaced by so-long-mode). In extreme cases this can prevent delays of several minutes, and make Emacs responsive almost immediately. Type 'M-x so-long-commentary' for full documentation.

11. Incompatible Lisp Changes in Emacs 27.1

11.1. Incomplete destructive splicing support has been removed.

Support for Common Lisp style destructive splicing (",.") was incomplete and broken for a long time. It has now been removed.

This means that backquote substitution now works for identifiers starting with a period ("."). Consider the following example:

(let ((.foo 42)) `,.foo)

In the past, this would have incorrectly evaluated to '(\,\. foo)', but will now instead evaluate to '42'.

11.2. The REGEXP in magic-mode-alist is now matched case-sensitively.

Likewise for magic-fallback-mode-alist.

11.3. add-hook does not always add to the front or the end any more.

The replacement of 'append' with 'depth' implies that the function is not always added to the very front (when append/depth is nil) or the very end (when append/depth is t) any more because other functions on the hook may have specified higher/lower depths. This makes it possible to control the ordering of functions more precisely, as was already possible in add-function and advice-add.

11.4. In 「compilation-error-regexp-alist」 the old undocumented feature

where 'line' could be a function of 2 arguments has been dropped.

11.5. define-fringe-bitmap is always defined, even when Emacs is built

without any GUI support.

11.6. Just loading a theme's file no longer activates the theme's settings.

Loading a theme with 'M-x load-theme' still activates the theme, as it did before. However, loading the theme's file with 'M-x load-file', or using 'require' or 'load' in a Lisp program, doesn't actually apply the theme's settings until you either invoke 'M-x enable-theme' or type 'M-x load-theme'. (In a Lisp program, calling enable-theme or invoking load-theme with NO-ENABLE argument omitted or nil has the same effect of activating a theme whose file has been loaded.) The special case of the 'user' theme is an exception: it is frequently used for ad-hoc customizations, so the settings of that theme are by default applied immediately.

The variable 'custom–inhibit-theme-enable' controls this behavior; its default value changed in Emacs 27.1.

11.7. The REPETITIONS argument of benchmark-run can now also be a variable.

11.8. Interpretation of relative 'HOME' directory has changed.

If "$HOME" is set to a relative file name, expand-file-name now interprets it relative to the directory where Emacs was started, not relative to the default-directory of the current buffer. We recommend always setting "$HOME" to an absolute file name, so that its meaning is independent of where Emacs was started.

11.9. file-name-absolute-p no longer considers "~foo" to be an absolute

file name if there is no user named "foo".

11.10. The FILENAME argument to file-name-base is now mandatory and no

longer defaults to buffer-file-name.

11.11. File metadata primitives now signal an error if I/O, access, or

other serious errors prevent them from determining the result. Formerly, these functions often (though not always) silently returned nil. For example, if there is an access error, I/O error or low-level integer overflow when getting the attributes of a file F, '(file-attributes F)' now signals an error instead of returning nil. These functions still behave as before if the only problem is that the file does not exist. The affected primitives are directory-files-and-attributes, file-acl, file-attributes, file-modes, file-newer-than-file-p, file-selinux-context, file-system-info, and set-visited-file-modtime.

11.12. The function eldoc-message now accepts a single argument.

Programs that called it with multiple arguments before should pass them through 'format' first. Even that is discouraged: for ElDoc support, you should set eldoc-documentation-function instead of calling eldoc-message directly.

11.13. Old-style backquotes now generate an error.

They have been generating warnings for a decade. To interpret old-style backquotes as new-style, bind the new variable 「force-new-style-backquotes」 to t.

11.14. Defining a Common Lisp structure using cl-defstruct or

cl-struct-define whose name clashes with a builtin type (e.g., 'integer' or 「hash-table」) now signals an error.

11.15. When formatting a floating-point number as an octal or hexadecimal

integer, Emacs now signals an error if the number is too large for the implementation to format.

11.16. 'logb' now returns infinity when given an infinite or zero argument,

and returns a NaN when given a NaN. Formerly, it returned an extreme fixnum for such arguments.

11.17. Some functions and variables obsolete since Emacs 22 have been removed:

「archive-mouse-extract」, 「assoc-ignore-case」, 「assoc-ignore-representation」, 「backward-text-line」, 「blink-cursor」, 「bookmark-exit-hooks」, 'c-opt-op-identitier-prefix', 「comint-use-prompt-regexp-instead-of-fields」, 「compilation-finish-function」, 「count-text-lines」, 「cperl-vc-header-alist」, 「custom-face-save-command」, 「cvs-display-full-path」, 'cvs-fileinfo->full-path', 「delete-frame-hook」, 「derived-mode-class」, 「describe-char-after」, 「describe-project」, 「desktop-basefilename」, 「desktop-buffer-handlers」, 「desktop-buffer-misc-functions」, 「desktop-buffer-modes-to-save」, 「desktop-enable」, 「desktop-load-default」, 「dired-omit-files-p」, 「disabled-command-hook」, 「dungeon-mode-map」, 「electric-nroff-mode」, 「electric-nroff-newline」, 「electric-perl-terminator」, 「executing-macro」, 「focus-frame」, 「forward-text-line」, 「generic-define-mswindows-modes」, 「generic-define-unix-modes」, 「generic-font-lock-defaults」, 「goto-address-at-mouse」, 「highlight-changes-colours」, 「ibuffer-elide-long-columns」, 「ibuffer-hooks」, 「ibuffer-mode-hooks」, 「icalendar-convert-diary-to-ical」, 「icalendar-extract-ical-from-buffer」, 「imenu-always-use-completion-buffer-p」, 「ipconfig-program」, 「ipconfig-program-options」, 「isearch-lazy-highlight-cleanup」, 「isearch-lazy-highlight-initial-delay」, 「isearch-lazy-highlight-interval」, 「isearch-lazy-highlight-max-at-a-time」, 「iswitchb-use-fonts」, 「latin1-char-displayable-p」, 「mouse-wheel-click-button」, 「mouse-wheel-down-button」, 「mouse-wheel-up-button」, 「new-frame」, 「pascal-outline」, 「process-kill-without-query」, 「recentf-menu-append-commands-p」, 「rmail-pop-password」, 「rmail-pop-password-required」, 「savehist-load」, 「set-default-font」, 「spam-list-of-processors」, 「speedbar-add-ignored-path-regexp」, 「speedbar-buffers-line-path」, 「speedbar-ignored-path-expressions」, 「speedbar-ignored-path-regexp」, 「speedbar-line-path」, 「speedbar-path-line」, 「timer-set-time-with-usecs」, 「tooltip-gud-display」, 「tooltip-gud-modes」, 「tooltip-gud-toggle-dereference」, 「unfocus-frame」, 「unload-hook-features-list」, 「update-autoloads-from-directories」, 「vc-comment-ring」, 「vc-comment-ring-index」, 「vc-comment-search-forward」, 「vc-comment-search-reverse」, 「vc-comment-to-change-log」, 「vc-diff-switches-list」, 「vc-next-comment」, 「vc-previous-comment」, 「view-todo」, 'x-lost-selection-hooks', 'x-sent-selection-hooks'.

11.18. Further functions and variables obsolete since Emacs 24 have been removed:

「default-directory-alist」, 「dired-default-directory」, 「dired-default-directory-alist」, 「dired-enable-local-variables」, 「dired-hack-local-variables」, 「dired-local-variables-file」, 「dired-omit-here-always」.

11.19. Garbage collection no longer treats miscellaneous objects specially;

they are now allocated like any other pseudovector. As a result, the garbage-collect and 「memory-use-count」 functions no longer return a 'misc' component, and the 「misc-objects-consed」 variable has been removed.

11.20. Reversed character ranges are no longer permitted in 'rx'.

Previously, ranges where the starting character is greater than the ending character were silently omitted. For example, '(rx (any "@z-a" (?9 . ?0)))' would match '@' only. Now, such 'rx' expressions generate an error.

11.21. Internal 'rx' functions and variables have been removed,

as a consequence of an improved implementation. Packages using these should use the public 'rx' and rx-to-string instead. 「rx-constituents」 is still available for compatibility, but the new extension mechanism is preferred: rx-define, rx-let and rx-let-eval.

11.22. text-mode no longer sets the value of indent-line-function.

The global value of indent-line-function, which defaults to indent-relative, will no longer be reset locally when turning on text-mode.

To get back the old behavior, add a function to text-mode-hook which performs '(setq-local indent-line-function #'indent-relative)'.

11.23. make-process no longer accepts a non-nil ':stop' key. This has

never worked reliably, and now causes an error.

11.24. 'eventp' no longer returns non-nil for lists whose car is nil.

This is consistent with the fact that nil, though a symbol, is not a valid event type.

11.25. The obsolete package xesam.el (since Emacs 24) has been removed.

11.26. The XBM image handler now accepts a ':stride' argument, which should

be specified in image specs representing the entire bitmap as a single bool vector.

11.27. regexp-quote may return its argument string.

If the argument needs no quoting, it can be returned instead of a copy.

11.28. Mouse scroll up and down with control key modifier changes font size.

Previously, the control key modifier was used to scroll up or down by an amount which was close to near a full screen. This is now instead available by scrolling with the meta modifier key.

To get the old behavior back, customize the user option mouse-wheel-scroll-amount, or add the following to your init file:

(customize-set-variable 'mouse-wheel-scroll-amount '(5 ((shift) . 1) ((control) . nil)))

By default, the font size will be changed in the window that the mouse pointer is over. To change this behavior, you can customize the user option mouse-wheel-follow-mouse. Note that this will also affect scrolling.

11.29. Mouse scroll up and down with control key modifier also works on images

where it scales the image under the mouse pointer.

11.30. help-follow-symbol now signals user-error if point (or the

position pointed to by the argument POS) is not in a symbol.

11.31. The options.el library has been removed.

It was obsolete since Emacs 22.1, replaced by customize.

11.32. The tls.el and starttls.el libraries are now marked obsolete.

Use of built-in libgnutls based functionality (described in the Emacs GnuTLS manual) is recommended instead.

11.33. The url-ns.el library is now marked obsolete.

This library is used to open configuration files for the long defunct web browser Netscape, and is no longer relevant.

12. Lisp Changes in Emacs 27.1

12.1. Emacs Lisp integers can now be of arbitrary size.

Emacs uses the GNU Multiple Precision (GMP) library to support integers whose size is too large to support natively. The integers supported natively are known as "fixnums", while the larger ones are "bignums". The new predicates 'bignump' and 'fixnump' can be used to distinguish between these two types of integers.

All the arithmetic, comparison, and logical (a.k.a. "bitwise") operations where bignums make sense now support both fixnums and bignums. However, note that unlike fixnums, bignums will not compare equal with 'eq', you must use 'eql' instead. (Numerical comparison with '=' works on both, of course.)

Since large bignums consume a lot of memory, Emacs limits the size of the largest bignum a Lisp program is allowed to create. The nonnegative value of the new variable integer-width specifies the maximum number of bits allowed in a bignum. Emacs signals an integer overflow error if this limit is exceeded.

Several primitive functions formerly returned floats or lists of integers to represent integers that did not fit into fixnums. These functions now simply return integers instead. Affected functions include functions like encode-char that compute code-points, functions like file-attributes that compute file sizes and other attributes, functions like process-id that compute process IDs, and functions like user-uid and group-gid that compute user and group IDs.

12.2. 「overflow-error」 is now documented as a subcategory of 「range-error」.

Formerly it was undocumented, and was (incorrectly) a subcategory of 「domain-error」.

12.3. Time values

12.3.1. New function time-convert converts Lisp time values to Lisp

timestamps of various forms, including a new timestamp form '(TICKS . HZ)' where TICKS is an integer and HZ a positive integer denoting a clock frequency.

12.3.2. Although the default timestamp format is still '(HI LO US PS)',

it is planned to change in a future Emacs version, to exploit bignums. The documentation has been updated to mention that the timestamp format may change and that programs should use functions like format-time-string, decode-time, and time-convert rather than probing the innards of a timestamp directly, or creating a timestamp by hand.

12.3.3. Decoded (calendrical) timestamps now have subsecond resolution.

This affects decode-time, which generates these timestamps, as well as functions like encode-time that accept them. The subsecond info is present as a '(TICKS . HZ)' value in the seconds element of a decoded timestamp, and decode-time has a new optional FORM argument specifying the form of the seconds member. For example, if X is the timestamp '(1566009571321878186 . 1000000000)', which represents "2019-08-17 02:39:31.321878186 UTC", '(decode-time X t t)' returns '((31321878186 . 1000000000) 39 2 17 8 2019 6 nil 0)' instead of the traditional '(31 39 2 17 8 2019 6 nil 0)' returned by plain '(decode-time X t)'. Although the default FORM is currently 'integer', which truncates the seconds to an integer and is the traditional behavior, this default may change in future Emacs versions, so callers requiring an integer should specify FORM explicitly.

12.3.4. encode-time supports a new API '(encode-time TIME)'.

The old encode-time API is still supported.

12.3.5. A new package to parse ISO 8601 time, date, durations and

intervals has been added. The main function to use is 「iso8601-parse」, but there's also 「iso8601-parse-date」, 「iso8601-parse-time」, 「iso8601-parse-duration」 and 「iso8601-parse-interval」. All these functions return decoded time structures, except the final one, which returns three of them (start, end and duration).

12.3.6. time-add, time-subtract, and time-less-p now accept

infinities and NaNs too, and propagate them or return nil like floating-point operators do. If both arguments are finite, these functions now return exact results instead of rounding in some cases, and they also avoid excess precision when that is easy.

12.3.7. New function time-equal-p compares time values for equality.

12.3.8. format-time-string supports a new conversion specifier flag '+'

that acts like the '0' flag but also puts a '+' before nonnegative years containing more than four digits. This is for compatibility with POSIX.1-2017.

12.3.9. To access (or alter) the elements of a decoded time value, the

decoded-time-second, decoded-time-minute, decoded-time-hour, decoded-time-day, decoded-time-month, decoded-time-year, decoded-time-weekday, decoded-time-dst and decoded-time-zone accessors can be used.

12.3.10. The new functions date-days-in-month (which will say how many

days there are in a month in a specific year), date-ordinal-to-time (that computes the date of an ordinal day), decoded-time-add (for doing computations on a decoded time structure), make-decoded-time (for making a decoded time structure with only the given keywords filled out), and decoded-time-set-defaults (which fills in nil elements as if it's midnight January 1st, 1970) have been added.

12.3.11. In the DST slot, encode-time and parse-time-string now return -1

if it is not known whether daylight saving time is in effect. Formerly they were inconsistent: encode-time returned t in this situation, whereas parse-time-string returned nil. Now they consistently use nil to mean that DST is not in effect, and use -1 to mean that it is not known whether DST is in effect.

12.4. New macro benchmark-progn.

This macro works like 'progn', but messages how long it takes to evaluate the body forms. The value of the last form is the return value.

12.5. New function read-char-from-minibuffer.

This function works like read-char, but uses read-from-minibuffer to read a character, so it maintains a history that can be navigated via usual minibuffer keystrokes 【M-p】/【M-n】.

12.6. New variables set-message-function and clear-message-function

can be used to specify functions to show and clear messages that normally are displayed in the echo area.

12.7. setq-local can now set an arbitrary number of variables, which

makes the syntax more like 'setq'.

12.8. reveal-mode can now also be used for more than to toggle between

invisible and visible: It can also toggle 'display' properties in overlays. This is only done on 'display' properties that have the 「reveal-toggle-invisible」 property set.

12.9. process-contact now takes an optional NO-BLOCK argument to allow

not waiting for a process to be set up.

12.10. New variable read-process-output-max controls sub-process throughput.

This variable determines how many bytes can be read from a sub-process in one read operation. The default, 4096 bytes, was previously a hard-coded constant. Setting it to a larger value might enhance throughput of reading from sub-processes that produce vast (megabytes) amounts of data in one go.

12.11. The new user option quit-window-hook is now run first when

executing the quit-window command.

12.12. The user options help-enable-completion-auto-load,

help-enable-auto-load and 「vhdl-project-auto-load」, as well as the function 「vhdl-auto-load-project」 have been renamed to have "autoload" without the hyphen in their names. Obsolete aliases from the old names have been added.

12.13. Buttons (created with make-button and related functions) can

now use the 「button-data」 property. If present, the data in this property will be passed on to the 'action' function instead of the button itself in button-activate.

12.14. 'defcustom' now takes a ':local' keyword that can be either t or

'permanent', which mean that the variable should be automatically buffer-local. 'permanent' also sets the variable's 「permanent-local」 property.

12.15. The new macro with-suppressed-warnings can be used to suppress

specific byte-compile warnings.

12.16. The new macro ignore-error is like ignore-errors, but takes a

specific error condition, and will only ignore that condition. (This can also be a list of conditions.)

12.17. The new function byte-compile-info-message can be used to output

informational messages that look pleasing during the Emacs build.

12.18. New help-fns-describe-variable-functions hook.

It makes it possible to add metadata information to describe-variable.

12.19. i18n (internationalization)

12.19.1. 'ngettext' can be used now to return the right plural form

according to the given numeric value.

12.20. inhibit-null-byte-detection is renamed to inhibit-nul-byte-detection.

12.21. self-insert-command takes the char to insert as (optional) argument.

12.22. lookup-key can take a list of keymaps as argument.

12.23. condition-case now accepts t to match any error symbol.

12.24. New function proper-list-p.

Given a proper list as argument, this predicate returns its length; otherwise, it returns nil. format-proper-list-p is now an obsolete alias for the new function.

12.25. define-minor-mode automatically documents the meaning of ARG.

12.26. The function 'recenter' now accepts an additional optional argument.

By default, calling 'recenter' will not redraw the frame even if recenter-redisplay is non-nil. Call 'recenter' with the new second argument non-nil to force redisplay per recenter-redisplays value.

12.27. New functions major-mode-suspend and major-mode-restore.

Use them when switching temporarily to another major mode, e.g. for hexl-mode, or to switch between c-mode and image-mode in XPM.

12.28. New macro dolist-with-progress-reporter.

This works like 'dolist', but reports progress similar to dotimes-with-progress-reporter.

12.29. New hook after-delete-frame-functions.

This works like delete-frame-functions, but runs after the frame to be deleted has been made dead and removed from the frame list.

12.30. The function provided-mode-derived-p was extended to support aliases.

The function now returns non-nil when the argument MODE is derived from any alias of any of MODES.

12.31. New frame focus state inspection interface.

The hooks focus-in-hook and focus-out-hook are now obsolete. Instead, attach to after-focus-change-function using add-function and inspect the focus state of each frame using frame-focus-state.

12.32. Emacs now requests and recognizes focus-change notifications from TTYs.

On terminal emulators that support the feature, Emacs can now support focus-in-hook and focus-out-hook for TTY frames.

12.33. Window-specific face remapping.

Face specifications (of the kind used in face-remapping-alist) now support filters, allowing faces to vary between different windows displaying the same buffer. See the node "(elisp) Face Remapping" of the Emacs Lisp Reference manual for more detail.

12.34. Window change functions have been redesigned.

Hooks reacting to window changes run now only when redisplay detects that a change has actually occurred. Six hooks are now provided: window-buffer-change-functions (run after window buffers have changed), window-size-change-functions (run after a window was assigned a new buffer or size), window-configuration-change-hook (like the former but run also when a window was deleted), window-selection-change-functions (run when the selected window changed) and window-state-change-functions and window-state-change-hook (run when any of the preceding ones is run). Applications can enforce running the latter two using the new function set-frame-window-state-change. window-scroll-functions are unaffected by these changes.

In addition, a number of functions now allow the caller to detect what has changed since last redisplay: window-old-buffer returns for any window the buffer it showed at that time. old-selected-window and old-selected-frame return the window and frame that were selected during last redisplay. window-old-pixel-width (renamed from window-pixel-width-before-size-change), window-old-pixel-height (renamed from window-pixel-height-before-size-change), window-old-body-pixel-width and window-old-body-pixel-height return the total and body sizes of any window during last redisplay.

Also run-window-configuration-change-hook is declared obsolete.

See the section "(elisp) Window Hooks" in the Elisp manual for a detailed explanation of the new behavior.

12.35. Scroll bar and fringe settings can now be made persistent for windows.

The functions set-window-scroll-bars and set-window-fringes now have a new optional argument that makes the settings they produce reliably survive subsequent invocations of set-window-buffer.

12.36. New user option resize-mini-frames.

This option allows automatically resizing minibuffer-only frames similarly to how minibuffer windows are resized on "normal" frames.

12.37. New buffer display action function display-buffer-in-direction.

This function allows specifying the location of the window chosen by display-buffer in various ways.

12.38. New buffer display action alist entry 'dedicated'.

Such an entry allows specifying the dedicated status of a window created by display-buffer.

12.39. New buffer display action alist entry window-min-height.

Such an entry allows specifying a minimum height of the window used for displaying a buffer. display-buffer-below-selected is the only action function to respect it at the moment.

12.40. New buffer display action alist entry 'direction'.

This entry is used to specify the location of the window chosen by display-buffer-in-direction.

12.41. Additional meaning of display action alist entry 'window'.

A 'window' entry can now also specify a reference window for display-buffer-in-direction.

12.42. The function assoc-delete-all now takes an optional predicate argument.

12.43. New function string-distance to calculate the Levenshtein distance

between two strings.

12.44. print-quoted now defaults to t, so if you want to see

'(quote x)' instead of 'x you will have to bind it to nil where applicable.

12.45. Numbers formatted via '%o' or '%x' are now formatted as signed integers.

This avoids problems in calls like '(read (format "#x%x" -1))', and is more compatible with bignums. To get the traditional machine-dependent behavior, set the experimental variable binary-as-unsigned to t, and if the new behavior breaks your code please email <32252@debbugs.gnu.org>. Because '%o' and '%x' can now format signed integers, they now support the '+' and space flags.

12.46. In Emacs Lisp mode, symbols with confusable quotes are highlighted.

For example, the first character in '‘foo' would be highlighted in font-lock-warning-face.

12.47. Omitting variables after '&optional' and '&rest' is now allowed.

For example '(defun foo (&optional))' is no longer an error. This is sometimes convenient when writing macros. See the ChangeLog entry titled "Allow '&rest' or '&optional' without following variable (Bug#29165)" for a full listing of which arglists are accepted across versions.

12.48. Internal parsing commands now use syntax-ppss and disregard

open-paren-in-column-0-is-defun-start. This affects mostly things like forward-comment, scan-sexps, and forward-sexp when parsing backward. The new variable comment-use-syntax-ppss can be set to nil to recover the old behavior if needed. This also means that there is no longer any need to precede opening brackets at the start of a line inside documentation strings with a backslash, although there is no harm in doing so to make the code easier to edit with an older Emacs version.

12.49. New symbolic accessor functions for a parse state list.

The new accessor functions ppss-depth, 「ppss-list-start」, 「ppss-last-sexp-start」, ppss-string-terminator, 「comment-depth」, 「quoted-p」, comment-style, 「comment-or-string-start」, 「open-parens」, and 「two-character-syntax」 can be used on the list value returned by parse-partial-sexp and syntax-ppss.

12.50. The 「server-name」 and 「server-socket-dir」 variables are set when a

socket has been passed to Emacs.

12.51. The file-system-info function is now available on all platforms.

instead of just Microsoft platforms. This fixes a get-free-disk-space bug on OS X 10.8 and later.

12.52. The function get-free-disk-space returns now a non-nil value for

remote systems, which support this check.

12.53. memory-limit now returns a better estimate of memory consumption.

12.54. When interpreting gc-cons-percentage, Emacs now estimates the

heap size more often and (we hope) more accurately. e.g., formerly '(progn (let ((gc-cons-percentage 0.8)) BODY1) BODY2)' continued to use the 0.8 value during BODY2 until the next garbage collection, but that is no longer true. Applications may need to re-tune their GC tricks.

12.55. New macro combine-change-calls arranges to call the change hooks

(before-change-functions and after-change-functions) just once each around a sequence of lisp forms, given a region. This is useful when a function makes a possibly large number of repetitive changes and the change hooks are time consuming.

12.56. 'eql', make-hash-table, etc. now treat NaNs consistently.

Formerly, some of these functions ignored signs and significands of NaNs. Now, all these functions treat NaN signs and significands as significant. For example, '(eql 0.0e+NaN -0.0e+NaN)' now returns nil because the two NaNs have different signs; formerly it returned t. Also, Emacs now reads and prints NaN significands; e.g., if X is a NaN, '(format "%s" X)' now returns "0.0e+NaN", "1.0e+NaN", etc., depending on X's significand.

12.57. The function make-string accepts an additional optional argument.

If the optional third argument is non-nil, make-string will produce a multibyte string even if its second argument is an ASCII character.

12.58. '(format "%d" X)' no longer mishandles a floating-point number X that

does not fit in a machine integer.

12.59. New coding-system 'ibm038'.

This is the International EBCDIC encoding, also available as aliases 「ebcdic-int」 and 'cp038'.

12.60. New JSON parsing and serialization functions json-serialize,

json-insert, json-parse-string, and json-parse-buffer. These are implemented in C using the Jansson library.

12.61. New function ring-resize.

ring-resize can be used to grow or shrink a ring.

12.62. New function flatten-tree.

flatten-list is provided as an alias. These functions take a tree and 'flatten' it such that the result is a list of all the terminal nodes.

12.63. zlib-decompress-region can partially decompress corrupted data.

If the new optional ALLOW-PARTIAL argument is passed, then the data that was decompressed successfully before failing will be inserted into the buffer.

12.64. Image mode

12.64.1. New library Exif.

An Exif library has been added that can parse JPEG files and output data about creation times and orientation and the like. exif-parse-file and exif-parse-buffer are the main interface functions.

12.64.2. image-mode now uses this library to automatically rotate images

according to the orientation in the Exif data, if any.

12.64.3. The command image-rotate now accepts a prefix argument.

With a prefix argument, image-rotate now rotates the image at point 90 degrees counter-clockwise, instead of the default clockwise.

12.64.4. In image-mode the image is resized automatically to fit in window.

By default, the image will resize upon first display and whenever the window's dimensions change. Two user options image-auto-resize and image-auto-resize-on-window-resize control the resizing behavior (including the possibility to disable auto-resizing). A new prefix key 's' contains the commands that can be used to fit the image to the window manually.

12.64.5. Some image-mode variables are now buffer-local.

The image parameters image-transform-rotation, image-transform-scale and image-transform-resize are now declared buffer-local, so each buffer could have its own values for these parameters.

12.64.6. Three new image-mode commands have been added: 'm', which marks

the file in the dired buffer(s) for the directory the file is in; 'u', which unmarks the file; and 'w', which pushes the current buffer's file name to the kill ring.

12.64.7. New library image-converter.

If you need to view exotic image formats for which Emacs doesn't have native support, customize the new user option image-use-external-converter to t. If your system has GraphicsMagick, ImageMagick or 'ffmpeg' installed, they will then be used to convert images automatically before displaying them.

12.64.8. auto-mode-alist now includes many of the types typically

supported by the external image converters, like WEPB, BMP and ICO. These now default to using image-mode.

12.64.9. imagemagick-types-inhibit disables using ImageMagick by default.

image-mode started using ImageMagick by default for all images some years back. It now respects imagemagick-types-inhibit as a way to disable that.

12.65. Modules

12.65.1. The function 'load' now behaves correctly when loading modules.

Specifically, it puts the module name into load-history, prints loading messages if requested, and protects against recursive loads.

12.65.2. New module environment function 'processinput' to process user

input while module code is running.

12.65.3. New module environment functions 'maketime' and 'extracttime' to

convert between timespec structures and Emacs Lisp time values.

12.65.4. New module environment functions 'makebiginteger' and

'extractbiginteger' to create and extract arbitrary-size integer values.

12.65.5. emacs-module.h now defines a macro 'EMACSMAJORVERSION' that expands

to the major version of the latest Emacs supported by the header.

12.66. The function read-variable now uses its own history list.

The history of variable names read by read-variable is recorded in the new variable custom-variable-history.

12.67. The functions string-to-unibyte and string-to-multibyte are no

longer declared obsolete. We have found that there are legitimate use cases for these functions, where there's no better alternative. We believe that the incorrect uses of these functions all but disappeared by now, so we are un-obsoleting them.

12.68. New function group-name returns a group name corresponding to GID.

12.69. make-process now takes a keyword argument ':file-handler'; if

that is non-nil, it will look for a file name handler for the current buffer's default-directory and invoke that file name handler to make the process. That way make-process can start remote processes.

12.70. '(locale-info 'paper)' now returns the paper size on systems that support it.

This is currently supported on GNUish hosts and on modern versions of MS-Windows.

12.71. The function regexp-opt, when given an empty list of strings, now

returns a regexp that never matches anything, which is an identity for this operation. Previously, the empty string was returned in this case.

12.72. New constant regexp-unmatchable contains a never-matching regexp.

It is a convenient and readable way to specify a regexp that should not match anything, and is as fast as any such regexp can be.

12.73. New functions to handle the URL variant of base-64 encoding.

New functions base64url-encode-string and base64url-encode-region implement the url-variant of base-64 encoding as defined in RFC4648.

The functions base64-decode-string and base64-decode-region now accept an optional argument to decode the URL variant of base-64 encoding.

12.74. The function file-size-human-readable accepts more optional arguments.

The new third argument is a string put between the number and unit; it defaults to the empty string. The new fourth argument is a string representing the unit to use; it defaults to "B" when the second argument is 'iec' and the empty string otherwise. We recommend a space or non-breaking space as third argument, and "B" as fourth argument, circumstances allowing.

12.75. format-spec has been expanded with several modifiers to allow

greater flexibility when customizing variables. The modifiers include zero-padding, upper- and lower-casing, and limiting the length of the interpolated strings. The function has now also been documented in the Emacs Lisp manual.

12.76. directory-files-recursively can now take an optional PREDICATE

parameter to control descending into subdirectories, and a FOLLOW-SYMLINK parameter to say that symbolic links that point to other directories should be followed.

12.77. New function 'xor' returns the boolean exclusive-or of its args.

The function was previously defined in array.el, but has been moved to subr.el so that it is available by default. It now always returns the non-nil argument when the other is nil. Several duplicates of 'xor' in other packages are now obsolete aliases of 'xor'.

12.78. define-globalized-minor-mode now takes BODY forms.

12.79. New text property 「help-echo-inhibit-substitution」.

Setting this on the first character of a help string disables conversions via substitute-command-keys.

12.80. New text property minibuffer-message.

Setting this on a character of the minibuffer text will display the temporary echo messages before that character, when messages need to be displayed while minibuffer is active.

12.81. 'undo' can be made to ignore the active region for a command

by setting 「undo-inhibit-region」 symbol property of that command to non-nil. This is used by mouse-drag-region to make the effect easier to undo immediately afterwards.

12.82. When called interactively, next-buffer and previous-buffer now

signal user-error if there is no buffer to switch to.

13. Changes in Emacs 27.1 on Non-Free Operating Systems

13.1. Battery status is now supported in all Cygwin builds.

Previously it was supported only in the Cygwin-w32 build.

13.2. Emacs now handles key combinations involving the macOS "command"

and "option" modifier keys more correctly.

13.3. MacOS modifier key behavior is now more adjustable.

The behavior of the macOS "Option", "Command", "Control" and "Function" keys can now be specified separately for use with ordinary keys, function keys and mouse clicks. This allows using them in their standard macOS way for composing characters.

13.4. The special handling of frame-title-format on NS where setting it

to t would enable the macOS proxy icon has been replaced with a separate variable, 「ns-use-proxy-icon」. frame-title-format will now work as on other platforms.

13.5. New primitive w32-read-registry.

This primitive lets Lisp programs access the MS-Windows Registry by retrieving values stored under a given key. It is intended to be used for supporting features such as XDG-like location of important files and directories.

13.6. The default value of w32-pipe-read-delay is now zero.

This speeds up reading output from sub-processes that produce a lot of data.

This variable may need to be non-zero only when running DOS programs as Emacs subprocesses, which by now is not supported on modern versions of MS-Windows. Set this variable to 50 if for some reason you need the old behavior (and please report such situations to Emacs developers).

13.7. New variable w32-multibyte-code-page.

This variable holds the value of the multibyte code page used by the system. It is usually zero, which indicates that w32-ansi-code-page is being used, except in Far Eastern locales. When this variable is non-zero, Emacs at startup sets locale-coding-system to the corresponding encoding, instead of using w32-ansi-code-page.

13.8. The default value of inhibit-compacting-font-caches is t on MS-Windows.

Experience shows that compacting font caches causes more trouble on MS-Windows than it helps.

13.9. Font lookup on MS-Windows was improved to support rare scripts.

To activate the improvement, run the new function w32-find-non-USB-fonts once per Emacs session, or assign to the new variable w32-non-USB-fonts the list of scripts and the corresponding fonts. See the documentation of this function and variable in the Emacs manual for more details.

13.10. On NS the behavior of drag and drop can now be modified by use of

modifier keys in line with Apples guidelines. This makes the drag and drop behavior more consistent, as previously the sending application was able to 'set' modifiers without the knowledge of the user.

13.11. On NS multicolor font display is enabled again since it is also

implemented in Emacs on free operating systems via Cairo drawing.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

GNU Emacs is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with GNU Emacs. If not, see https://www.gnu.org/licenses/.

Created: 2023-08-03 Thu 12:13