Merge from origin/emacs-27

2f9bfaef21 (origin/emacs-27) ; Fix last change
520fd3e728 * lisp/env.el (substitute-env-vars): Doc fix.  (Bug#40948)
85544f8ef5 * lisp/isearch.el: Fix lazy-highlighting and lazy-counting...
d83cc05a73 Fix error in ERC when 'erc-server-coding-system' is custom...
16fed05ba8 Avoid crashes on TTY frames with over-long compositions
0278741676 Fix typo in custom.texi
9f5ae717fb * test/lisp/simple-tests.el (with-shell-command-dont-erase...
1f76a16ed3 * lisp/image-mode.el (image-mode-map): Update menu items.
f0e1bf56f0 Fix bugs in tab-bar and tab-line and mention remaining fea...
f0b9f18457 Make shell-command tests fit for tcsh.
68f4a740a1 Remove doc duplication
ac31cd384c * etc/NEWS: Fix inconsistencies.

# Conflicts:
#	etc/NEWS

6 files changed, 54 insertions, 28 deletions

diff --git a/lisp/env.el b/lisp/env.el
index ca2a9773b4e..6de90385a35 100644
--- a/lisp/env.el
+++ b/lisp/env.el
@@ -68,10 +68,10 @@ with a character not a letter, digit or underscore; otherwise, enclose
 the entire variable name in braces.  For instance, in `ab$cd-x',
 `$cd' is treated as an environment variable.
 
-If WHEN-DEFINED is nil, references to undefined environment variables
-are replaced by the empty string; if it is a function, the function is called
-with the variable name as argument and should return the text with which
-to replace it or nil to leave it unchanged.
+If WHEN-UNDEFINED is omitted or nil, references to undefined environment
+variables are replaced by the empty string; if it is a function, the
+function is called with the variable's name as argument, and should return
+the text with which to replace it, or nil to leave it unchanged.
 If it is non-nil and not a function, references to undefined variables are
 left unchanged.
 
diff --git a/lisp/erc/erc-backend.el b/lisp/erc/erc-backend.el
index 57c8e730b83..1e2526f35ce 100644
--- a/lisp/erc/erc-backend.el
+++ b/lisp/erc/erc-backend.el
@@ -466,7 +466,8 @@ If this is set to nil, never try to reconnect."
 The length is specified in `erc-split-line-length'.
 
 Currently this is called by `erc-send-input'."
-  (let ((charset (car (erc-coding-system-for-target nil))))
+  (let* ((coding (erc-coding-system-for-target nil))
+         (charset (if (consp coding) (car coding) coding)))
     (with-temp-buffer
       (insert longline)
       ;; The line lengths are in octets, not characters (because these
diff --git a/lisp/image-mode.el b/lisp/image-mode.el
index 3ee185a0dc5..480b2e6b26e 100644
--- a/lisp/image-mode.el
+++ b/lisp/image-mode.el
@@ -505,16 +505,22 @@ call."
         "--"
         ["Fit Frame to Image" image-mode-fit-frame :active t
          :help "Resize frame to match image"]
+        ["Fit Image to Window (Best Fit)" image-transform-fit-both
+         :help "Resize image to match the window height and width"]
         ["Fit to Window Height" image-transform-fit-to-height
          :help "Resize image to match the window height"]
         ["Fit to Window Width" image-transform-fit-to-width
          :help "Resize image to match the window width"]
-        ["Fit to Window Height and Width" image-transform-fit-both
-         :help "Resize image to match the window height and width"]
+        ["Zoom In" image-increase-size
+         :help "Enlarge the image"]
+        ["Zoom Out" image-decrease-size
+         :help "Shrink the image"]
         ["Set Scale..." image-transform-set-scale
          :help "Resize image by specified scale factor"]
-        ["Rotate Image..." image-transform-set-rotation
+        ["Rotate Clockwise" image-rotate
          :help "Rotate the image"]
+        ["Set Rotation..." image-transform-set-rotation
+         :help "Set rotation angle of the image"]
         ["Reset Transformations" image-transform-reset
          :help "Reset all image transformations"]
         "--"
@@ -524,10 +530,10 @@ call."
            (image-dired default-directory))
          :active default-directory
          :help "Show thumbnails for all images in this directory"]
-        ["Next Image" image-next-file :active buffer-file-name
-         :help "Move to next image in this directory"]
         ["Previous Image" image-previous-file :active buffer-file-name
          :help "Move to previous image in this directory"]
+        ["Next Image" image-next-file :active buffer-file-name
+         :help "Move to next image in this directory"]
         ["Copy File Name" image-mode-copy-file-name-as-kill
          :active buffer-file-name
          :help "Copy the current file name to the kill ring"]
@@ -565,10 +571,10 @@ call."
         ["Reset Animation Speed" image-reset-speed
          :active image-multi-frame
          :help "Reset the speed of this image's animation"]
-        ["Next Frame" image-next-frame :active image-multi-frame
-         :help "Show the next frame of this image"]
         ["Previous Frame" image-previous-frame :active image-multi-frame
          :help "Show the previous frame of this image"]
+        ["Next Frame" image-next-frame :active image-multi-frame
+         :help "Show the next frame of this image"]
         ["Goto Frame..." image-goto-frame :active image-multi-frame
          :help "Show a specific frame of this image"]
         ))
diff --git a/lisp/isearch.el b/lisp/isearch.el
index e13a4dda83f..81e83d79509 100644
--- a/lisp/isearch.el
+++ b/lisp/isearch.el
@@ -319,7 +319,7 @@ this variable is set to the symbol `all-windows'."
   "Show match numbers in the search prompt.
 When both this option and `isearch-lazy-highlight' are non-nil,
 show the current match number and the total number of matches
-in the buffer (or its restriction)."
+in the buffer (or its restriction), including all hidden matches."
   :type 'boolean
   :group 'lazy-count
   :group 'isearch
@@ -3869,7 +3869,10 @@ Attempt to do the search exactly the way the pending Isearch would."
             (isearch-regexp-lax-whitespace
              isearch-lazy-highlight-regexp-lax-whitespace)
             (isearch-forward isearch-lazy-highlight-forward)
-            (search-invisible nil)      ; don't match invisible text
+            ;; Don't match invisible text unless it can be opened
+            ;; or when counting matches and user can visit hidden matches
+            (search-invisible (or (eq search-invisible 'open)
+                                  (and isearch-lazy-count search-invisible)))
             (retry t)
             (success nil))
         ;; Use a loop like in `isearch-search'.
diff --git a/lisp/tab-bar.el b/lisp/tab-bar.el
index 30ed1a4cf68..ce6d8c33dd1 100644
--- a/lisp/tab-bar.el
+++ b/lisp/tab-bar.el
@@ -87,10 +87,11 @@
 
 
 (defcustom tab-bar-select-tab-modifiers '()
-  "List of key modifiers for selecting a tab by its index digit.
-Possible modifiers are `control', `meta', `shift', `hyper', `super' and
-`alt'."
-  :type '(set :tag "Tab selection key modifiers"
+  "List of modifier keys for selecting a tab by its index digit.
+Possible modifier keys are `control', `meta', `shift', `hyper', `super' and
+`alt'.  To help you to select a tab by its number, you can customize
+`tab-bar-tab-hints' that will show tab numbers alongside the tab name."
+  :type '(set :tag "Tab selection modifier keys"
               (const control)
               (const meta)
               (const shift)
@@ -310,7 +311,8 @@ If nil, don't show it at all."
 
 (defcustom tab-bar-tab-hints nil
   "Show absolute numbers on tabs in the tab bar before the tab name.
-This helps to select the tab by its number using `tab-bar-select-tab'."
+This helps to select the tab by its number using `tab-bar-select-tab'
+and `tab-bar-select-tab-modifiers'."
   :type 'boolean
   :initialize 'custom-initialize-default
   :set (lambda (sym val)
@@ -563,9 +565,10 @@ Return its existing value or a new value."
 
 (defun tab-bar-select-tab (&optional arg)
   "Switch to the tab by its absolute position ARG in the tab bar.
-When this command is bound to a numeric key (with a prefix or modifier),
-calling it without an argument will translate its bound numeric key
-to the numeric argument.  ARG counts from 1."
+When this command is bound to a numeric key (with a prefix or modifier key
+using `tab-bar-select-tab-modifiers'), calling it without an argument
+will translate its bound numeric key to the numeric argument.
+ARG counts from 1."
   (interactive "P")
   (unless (integerp arg)
     (let ((key (event-basic-type last-command-event)))
@@ -664,7 +667,10 @@ to the numeric argument.  ARG counts from 1."
       (message "No more recent tabs"))))
 
 (defun tab-bar-switch-to-tab (name)
-  "Switch to the tab by NAME."
+  "Switch to the tab by NAME.
+Default values are tab names sorted by recency, so you can use \
+\\<minibuffer-local-map>\\[next-history-element]
+to get the name of the last visited tab, the second last, and so on."
   (interactive
    (let* ((recent-tabs (mapcar (lambda (tab)
                                  (alist-get 'name tab))
@@ -789,7 +795,7 @@ After the tab is created, the hooks in
                         (pcase tab-bar-new-tab-to
                           ('leftmost 0)
                           ('rightmost (length tabs))
-                          ('left (1- (or from-index 1)))
+                          ('left (or from-index 1))
                           ('right (1+ (or from-index 0)))
                           ((pred functionp)
                            (funcall tab-bar-new-tab-to))))))
@@ -920,7 +926,7 @@ for the last tab on a frame is determined by
           ;; Select another tab before deleting the current tab
           (let ((to-index (or (if to-index (1- to-index))
                               (pcase tab-bar-close-tab-select
-                                ('left (1- current-index))
+                                ('left (1- (if (< current-index 1) 2 current-index)))
                                 ('right (if (> (length tabs) (1+ current-index))
                                             (1+ current-index)
                                           (1- current-index)))
@@ -1004,7 +1010,7 @@ for the last tab on a frame is determined by
         (unless (eq frame (selected-frame))
           (select-frame-set-input-focus frame))
 
-        (let ((tabs (tab-bar-tabs)))
+        (let ((tabs (funcall tab-bar-tabs-function)))
           (setq index (max 0 (min index (length tabs))))
           (cl-pushnew tab (nthcdr index tabs))
           (when (eq index 0)
@@ -1102,6 +1108,8 @@ function `tab-bar-tab-name-function'."
     (setq tab-bar-history-omit nil)))
 
 (defun tab-bar-history-back ()
+  "Restore a previous window configuration used in the current tab.
+This navigates back in the history of window configurations."
   (interactive)
   (setq tab-bar-history-omit t)
   (let* ((history (pop (gethash (selected-frame) tab-bar-history-back)))
@@ -1119,6 +1127,8 @@ function `tab-bar-tab-name-function'."
       (message "No more tab back history"))))
 
 (defun tab-bar-history-forward ()
+  "Cancel restoration of the previous window configuration.
+This navigates forward in the history of window configurations."
   (interactive)
   (setq tab-bar-history-omit t)
   (let* ((history (pop (gethash (selected-frame) tab-bar-history-forward)))
@@ -1136,7 +1146,9 @@ function `tab-bar-tab-name-function'."
       (message "No more tab forward history"))))
 
 (define-minor-mode tab-bar-history-mode
-  "Toggle tab history mode for the tab bar."
+  "Toggle tab history mode for the tab bar.
+Tab history mode remembers window configurations used in every tab,
+and can restore them."
   :global t :group 'tab-bar
   (if tab-bar-history-mode
       (progn
diff --git a/lisp/tab-line.el b/lisp/tab-line.el
index eb279deab4c..7a2bdc0b72f 100644
--- a/lisp/tab-line.el
+++ b/lisp/tab-line.el
@@ -474,8 +474,12 @@ variable `tab-line-tabs-function'."
   "Template for displaying tab line for selected window."
   (let* ((tabs (funcall tab-line-tabs-function))
          (cache-key (list tabs
+                          ;; handle buffer renames
                           (buffer-name (window-buffer))
-                          (window-parameter nil 'tab-line-hscroll)))
+                          ;; handle tab-line scrolling
+                          (window-parameter nil 'tab-line-hscroll)
+                          ;; for setting face 'tab-line-tab-current'
+                          (eq (selected-window) (old-selected-window))))
          (cache (window-parameter nil 'tab-line-cache)))
     ;; Enable auto-hscroll again after it was disabled on manual scrolling.
     ;; The moment to enable it is when the window-buffer was updated.