Merge from origin/emacs-26

71be806 ; * etc/DEBUG: Minor clarification.
4403f89 Update the Emacs FAQ
40b3317 * etc/DEBUG: Minor copyedits.
850ff18 Clarify wording of NS drag n drop documentation
343d70b1 Improve kill-related documentation (bug#31209)
0b43224 * lisp/simple.el (region-extract-function): Don't hide the 'n...
d6e2c59 Fix pre- and post-command-hook errors in term.el
6cf83131e * doc/lispref/display.texi (Glyphless Chars): Fix grammar.
88d178c Fix macOS drag n drop event documentation

8 files changed, 145 insertions, 68 deletions

diff --git a/admin/release-process b/admin/release-process
index 3bb72b9735c..71ada82356c 100644
--- a/admin/release-process
+++ b/admin/release-process
@@ -99,6 +99,10 @@ significant changes and new features in the upcoming release, then
 describe the "benefits" from losing those features.  Be funny, use
 humor.  The text written for the previous releases can serve as an example.
 
+The Emacs FAQ (doc/misc/efaq.texi) also has a "What's new" section;
+for major releases a new section should be added listing the
+significant changes.
+
 Check cross-references between the manuals (e.g. from emacs to elisp)
 are correct.  You can use something like the following in the info
 directory in the Emacs build tree:
diff --git a/doc/emacs/macos.texi b/doc/emacs/macos.texi
index ef2e9448902..cfb63fe1d8c 100644
--- a/doc/emacs/macos.texi
+++ b/doc/emacs/macos.texi
@@ -107,30 +107,16 @@ Nextstep port.  For example, they affect things such as the modifier
 keys and the fullscreen behavior.  To see all such options, use
 @kbd{M-x customize-group @key{RET} ns @key{RET}}.
 
-@subsection Font and Color Panels
+@subsection Font Panel
 
 @findex ns-popup-font-panel
-The standard Mac / GNUstep font and color panels are accessible via
-Lisp commands.  The Font Panel may be accessed with @kbd{M-x
-ns-popup-font-panel}.  It will set the default font in the frame most
+The standard Mac / GNUstep font panel is accessible with @kbd{M-x
+ns-popup-font-panel} and will set the default font in the frame most
 recently used or clicked on.
 
 @c  To make the setting permanent, use @samp{Save Options} in the
 @c Options menu, or run @code{menu-bar-options-save}.
 
-@findex ns-popup-color-panel
-You can bring up a color panel with @kbd{M-x ns-popup-color-panel} and
-drag the color you want over the Emacs face you want to change.  Normal
-dragging will alter the foreground color.  Shift dragging will alter the
-background color.  To discard the settings, create a new frame and
-close the altered one.
-
-@c To make the changes permanent select the "Save Options"
-@c item in the "Options" menu, or run @code{menu-bar-options-save}.
-
-Useful in this context is the listing of all faces obtained by
-@kbd{M-x list-faces-display}.
-
 @cindex Core Text, on macOS
 @cindex font backend, on macOS
 In macOS, Emacs uses a Core Text based font backend
@@ -180,21 +166,12 @@ particular file, but also a particular line or sequence of lines in
 the file.  Emacs handles this by visiting that file and highlighting
 the requested line (@code{ns-open-file-select-line}).
 
-@item ns-drag-file
-This event occurs when a user drags files from another application
-into an Emacs frame.  The default behavior is to insert the contents
-of all the dragged files into the current buffer
-(@code{ns-insert-files}).  The list of dragged files is stored in the
-variable @code{ns-input-file}.
-
-@item ns-drag-color
-This event occurs when a user drags a color from the color well (or
-some other source) into an Emacs frame.  The default behavior is to
-alter the foreground color of the area the color was dragged onto
-(@code{ns-set-foreground-at-mouse}).  If this event is issued with a
-@key{Shift} modifier, Emacs changes the background color instead
-(@code{ns-set-background-at-mouse}).  The name of the dragged color is
-stored in the variable @code{ns-input-color}.
+@item ns-drag-n-drop
+This event occurs when a user drags an object from another application
+into an Emacs frame.  The default behavior is to open a file in the
+window under the mouse, or to insert text at point of the window under
+the mouse.  It may sometimes be necessary to use the @key{META} key in
+conjunction with dragging to force text insertion.
 
 @item ns-change-font
 This event occurs when the user selects a font in a Nextstep font
diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 02dc830e0ab..13a25af02c8 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -7235,8 +7235,8 @@ Characters of Unicode General Category [Cf], such as @samp{U+200E}
 images, such as @samp{U+00AD} (Soft Hyphen).
 
 @item no-font
-Characters for there is no suitable font, or which cannot be encoded
-by the terminal's coding system.
+Characters for which there is no suitable font, or which cannot be
+encoded by the terminal's coding system.
 @end table
 
 @c FIXME: this can also be 'acronym', but that's not currently
diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index 8cb6cf6242a..da09b4ae1c6 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -1143,7 +1143,7 @@ If @var{n} is zero, indicating a request for the latest kill,
 @code{current-kill} calls the value of
 @code{interprogram-paste-function} (documented below) before
 consulting the kill ring.  If that value is a function and calling it
-returns a string or a list of several string, @code{current-kill}
+returns a string or a list of several strings, @code{current-kill}
 pushes the strings onto the kill ring and returns the first string.
 It also sets the yanking pointer to point to the kill-ring entry of
 the first string returned by @code{interprogram-paste-function},
@@ -1156,8 +1156,10 @@ move the yanking pointer.
 @defun kill-new string &optional replace
 This function pushes the text @var{string} onto the kill ring and
 makes the yanking pointer point to it.  It discards the oldest entry
-if appropriate.  It also invokes the value of
-@code{interprogram-cut-function} (see below).
+if appropriate.  It also invokes the values of
+@code{interprogram-paste-function} (subject to
+the user option @code{save-interprogram-paste-before-kill})
+and @code{interprogram-cut-function} (see below).
 
 If @var{replace} is non-@code{nil}, then @code{kill-new} replaces the
 first element of the kill ring with @var{string}, rather than pushing
@@ -1169,8 +1171,10 @@ This function appends the text @var{string} to the first entry in the
 kill ring and makes the yanking pointer point to the combined entry.
 Normally @var{string} goes at the end of the entry, but if
 @var{before-p} is non-@code{nil}, it goes at the beginning.  This
-function also invokes the value of @code{interprogram-cut-function}
-(see below).
+function calls @code{kill-new} as a subroutine, thus causing the
+values of @code{interprogram-cut-function} and possibly
+@code{interprogram-paste-function} (see below) to be invoked by
+extension.
 @end defun
 
 @defvar interprogram-paste-function
diff --git a/doc/misc/efaq.texi b/doc/misc/efaq.texi
index b2cf006285d..96ca4657284 100644
--- a/doc/misc/efaq.texi
+++ b/doc/misc/efaq.texi
@@ -930,6 +930,7 @@ status of its latest version.
 @menu
 * Origin of the term Emacs::
 * Latest version of Emacs::
+* New in Emacs 26::
 * New in Emacs 25::
 * New in Emacs 24::
 * New in Emacs 23::
@@ -979,7 +980,7 @@ conventions}).
 Emacs @value{EMACSVER} is the current version as of this writing.  A version
 number with two components (e.g., @samp{24.5}) indicates a released
 version; three components indicate a development
-version (e.g., @samp{26.0.50} is what will eventually become @samp{26.1}).
+version (e.g., @samp{27.0.50} is what will eventually become @samp{27.1}).
 
 Emacs is under active development, hosted at
 @uref{https://savannah.gnu.org/projects/emacs/, Savannah}.
@@ -998,6 +999,80 @@ Emacs, type @kbd{C-h C-n} (@kbd{M-x view-emacs-news}).  As of Emacs 22,
 you can give this command a prefix argument to read about which features
 were new in older versions.
 
+@node New in Emacs 26
+@section What is different about Emacs 26?
+@cindex Differences between Emacs 25 and Emacs 26
+@cindex Emacs 26, new features in
+
+@itemize
+@cindex threads
+@item
+Emacs now provides a limited form of concurrency with Lisp threads.
+
+@cindex systemd support
+@item
+Emacs now supports @code{systemd}.  The new command-line option
+@option{--fg-daemon} is part of this support, it causes Emacs to run
+in the foreground instead of forking, as under @option{--daemon}.
+
+@item
+Emacs now supports 24-bit true color on text terminals which provide
+that feature.  @xref{Colors on a TTY}.
+
+@cindex double-buffering
+@item
+Emacs on X now supports double-buffering, which eliminates display
+flickering in most situations.
+
+@item
+You can now scroll the Emacs display horizontally using the mouse or
+touchpad.
+
+@cindex line number display
+@item
+Emacs display now includes an optional feature for display of line
+numbers via the @code{display-line-numbers-mode} command.  This
+feature is much faster than the equivalent display offered by packages
+such as @code{linum}, and also provides many optional features like
+relative line numbers.
+
+@cindex horizontal scrolling of current line
+@item
+The automatic horizontal scrolling of the window display when lines
+are truncated can now optionally be enabled only for the current line,
+the line where Emacs shows the cursor.  Under this mode, all the other
+window lines are not scrolled to show characters outside of the
+viewport.
+
+@item
+Letter-case conversions now honor special cases in Turkish and Greek
+scripts.
+
+@cindex Enchant support
+@item
+Support for Enchant is now part of the Emacs spell-checking commands.
+
+@item
+Tramp now supports Google Drive filesystems.
+
+@item
+Emacs can now be built while omitting the details of the machine on
+which it was built, thus making it easier to produce reproducible
+builds.
+
+@item
+Security vulnerability related to Enriched Text mode is removed.
+Enriched mode previously allowed saving @code{display} properties as
+part of text; those properties support evaluating arbitrary Lisp code,
+which opens a vulnerability for Emacs users receiving Enriched Text
+from external sources.  Execution of arbitrary Lisp forms in
+@code{display} properties decoded by Enriched Text mode is now
+disabled by default.
+@end itemize
+
+Consult the Emacs @file{NEWS} file (@kbd{C-h n}) for the full list of
+changes in Emacs 26.
+
 @node New in Emacs 25
 @section What is different about Emacs 25?
 @cindex Differences between Emacs 24 and Emacs 25
diff --git a/etc/DEBUG b/etc/DEBUG
index 49764fc9137..aeb447bae33 100644
--- a/etc/DEBUG
+++ b/etc/DEBUG
@@ -43,6 +43,11 @@ created in the 'src' directory.
 
 *** Configuring GDB
 
+To start GDB to debug Emacs, you can simply type "gdb ./emacs RET" at
+the shell prompt (assuming you do that from the directory of the Emacs
+executable, usually the 'src' sub-directory of the Emacs tree).
+However, we recommend starting GDB from Emacs, see below.
+
 When you debug Emacs with GDB, you should start GDB in the directory
 where the Emacs executable was made (the 'src' directory in the Emacs
 source tree).  That directory has a .gdbinit file that defines various
@@ -52,16 +57,19 @@ Emacs Redisplay problems".)
 
 Starting the debugger from Emacs, via the "M-x gdb" command (described
 below), when the current buffer visits one of the Emacs C source files
-will automatically start GDB in the 'src' directory.
+will automatically start GDB in the 'src' directory.  If you invoke
+"M-x gdb" from a buffer whose default directory is different, such as
+from the "*scratch*" buffer, you can change the default directory with
+the "M-x cd" command before starting the debugger.
 
-Some GDB versions by default do not automatically load .gdbinit files
-in the directory where you invoke GDB.  With those versions of GDB,
-you will see a warning when GDB starts, like this:
+Recent GDB versions by default do not automatically load .gdbinit
+files in the directory where you invoke GDB.  With those versions of
+GDB, you will see a warning when GDB starts, like this:
 
   warning: File ".../src/.gdbinit" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
 
 The simplest way to fix this is to add the following line to your
-~/.gdbinit file:
+~/.gdbinit file (creating such a file if it doesn't already exist):
 
   add-auto-load-safe-path /path/to/emacs/src/.gdbinit
 
@@ -133,9 +141,12 @@ to the debugger".
 
 You are now ready to start your debugging session.
 
+*** Running Emacs from GDB
+
 If you are starting a new Emacs session, type "run", followed by any
 command-line arguments (e.g., "-Q") into the *gud-emacs* buffer and
-press RET.
+press RET.  If you ran GDB outside of Emacs, type "run" followed by
+the command-line arguments at the GDB prompt instead.
 
 If you attached the debugger to a running Emacs, type "continue" into
 the *gud-emacs* buffer and press RET.
diff --git a/lisp/simple.el b/lisp/simple.el
index 863547a76ba..5446159d319 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -1067,14 +1067,14 @@ instead of deleted."
        (t
         (filter-buffer-substring (region-beginning) (region-end) method)))))
   "Function to get the region's content.
-Called with one argument METHOD.
-If METHOD is `delete-only', then delete the region; the return value
-is undefined.  If METHOD is nil, then return the content as a string.
-If METHOD is `bounds', then return the boundaries of the region
-as a list of cons cells of the form (START . END).
-If METHOD is anything else, delete the region and return its content
-as a string, after filtering it with `filter-buffer-substring', which
-is called with METHOD as its 3rd argument.")
+Called with one argument METHOD which can be:
+- nil: return the content as a string.
+- `delete-only': delete the region; the return value is undefined.
+- `bounds': return the boundaries of the region as a list of cons
+  cells of the form (START . END).
+- anything else: delete the region and return its content
+  as a string, after filtering it with `filter-buffer-substring', which
+  is called with METHOD as its 3rd argument.")
 
 (defvar region-insert-function
   (lambda (lines)
@@ -4355,12 +4355,11 @@ ring directly.")
   "The tail of the kill ring whose car is the last thing yanked.")
 
 (defcustom save-interprogram-paste-before-kill nil
-  "Save clipboard strings into kill ring before replacing them.
-When one selects something in another program to paste it into Emacs,
-but kills something in Emacs before actually pasting it,
-this selection is gone unless this variable is non-nil,
-in which case the other program's selection is saved in the `kill-ring'
-before the Emacs kill and one can still paste it using \\[yank] \\[yank-pop]."
+  "Save existing clipboard text into kill ring before replacing it.
+A non-nil value ensures that Emacs kill operations do not
+irrevocably overwrite existing clipboard text by saving it to the
+`kill-ring' prior to the kill.  Such text can subsequently be
+retrieved via \\[yank] \\[yank-pop]]."
   :type 'boolean
   :group 'killing
   :version "23.2")
@@ -4380,7 +4379,7 @@ Optional second argument REPLACE non-nil means that STRING will replace
 the front of the kill ring, rather than being added to the list.
 
 When `save-interprogram-paste-before-kill' and `interprogram-paste-function'
-are non-nil, saves the interprogram paste string(s) into `kill-ring' before
+are non-nil, save the interprogram paste string(s) into `kill-ring' before
 STRING.
 
 When the yank handler has a non-nil PARAM element, the original STRING
@@ -4416,20 +4415,24 @@ argument should still be a \"useful\" string for such uses."
   (if interprogram-cut-function
       (funcall interprogram-cut-function string)))
 
-;; It has been argued that this should work similar to `self-insert-command'
-;; which merges insertions in undo-list in groups of 20 (hard-coded in cmds.c).
+;; It has been argued that this should work like `self-insert-command'
+;; which merges insertions in `buffer-undo-list' in groups of 20
+;; (hard-coded in `undo-auto-amalgamate').
 (defcustom kill-append-merge-undo nil
-  "Whether appending to kill ring also makes \\[undo] restore both pieces of text simultaneously."
+  "Amalgamate appending kills with the last kill for undo.
+When non-nil, appending or prepending text to the last kill makes
+\\[undo] restore both pieces of text simultaneously."
   :type 'boolean
   :group 'killing
   :version "25.1")
 
 (defun kill-append (string before-p)
   "Append STRING to the end of the latest kill in the kill ring.
-If BEFORE-P is non-nil, prepend STRING to the kill.
-Also removes the last undo boundary in the current buffer,
- depending on `kill-append-merge-undo'.
-If `interprogram-cut-function' is set, pass the resulting kill to it."
+If BEFORE-P is non-nil, prepend STRING to the kill instead.
+If `interprogram-cut-function' is non-nil, call it with the
+resulting kill.
+If `kill-append-merge-undo' is non-nil, remove the last undo
+boundary in the current buffer."
   (let* ((cur (car kill-ring)))
     (kill-new (if before-p (concat string cur) (concat cur string))
               (or (= (length cur) 0)
diff --git a/lisp/term.el b/lisp/term.el
index cfb39c34e53..017b0221ecb 100644
--- a/lisp/term.el
+++ b/lisp/term.el
@@ -1456,6 +1456,9 @@ The main purpose is to get rid of the local keymap."
   (let ((buffer-read-only nil)
         (omax (point-max))
         (opoint (point)))
+    ;; Remove hooks to avoid errors due to dead process.
+    (remove-hook 'pre-command-hook #'term-set-goto-process-mark t)
+    (remove-hook 'post-command-hook #'term-goto-process-mark-maybe t)
     ;; Record where we put the message, so we can ignore it
     ;; later on.
     (goto-char omax)