GNU Emacs NEWS -- history of user-visible changes.

Copyright (C) 2014-2017 Free Software Foundation, Inc.
See the end of the file for license conditions.

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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.24, NEWS.23, NEWS.22, NEWS.21,
NEWS.20, NEWS.19, 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.

Temporary note:
+++ indicates that all necessary documentation updates are complete.
    (This means all relevant manuals in doc/ AND lisp doc-strings.)
--- means no change in the manuals is needed.
When you add a new item, use the appropriate mark if you are sure it applies,


* Installation Changes in Emacs 27.1

** The new configure option '--with-json' adds support for JSON using
the Jansson library.  It 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.


* Startup Changes in Emacs 27.1


* Changes in Emacs 27.1

+++
** New function 'logcount' calculates an integer's Hamming weight.


* Editing Changes in Emacs 27.1

---
** 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).


* Changes in Specialized Modes and Packages in Emacs 27.1

** Enhanced xterm support

*** New variable 'xterm-set-window-title' controls whether Emacs
sets the XTerm window title.  The default is to set the window title.


* New Modes and Packages in Emacs 27.1


* Incompatible Lisp Changes in Emacs 27.1

** The FILENAME argument to 'file-name-base' is now mandatory and no
longer defaults to 'buffer-file-name'.

---
** 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.

* Lisp Changes in Emacs 27.1


* Changes in Emacs 27.1 on Non-Free Operating Systems


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