Merge from origin/emacs-27

a3c2d186eb (origin/emacs-27) CC Mode: Fix the handling of two adjacen...
a1abf73c76 Fix combine-change-calls-1 for when buffer-undo-list is t
db37dd2e84 Don't misinterpret doc string as initial value
40b217c2bf Bump checkdoc-version to match library header
60418a1ab2 Explain how to unset mode bindings (Bug#39802)
7cafbbe964 Fix describe-variable on values with circular syntax (Bug#...
592b1cfee9 Improve documentation of next-error-highlight-no-select (b...

2 files changed, 15 insertions, 7 deletions

diff --git a/doc/emacs/building.texi b/doc/emacs/building.texi
index 272b08d08e9..38963f225ca 100644
--- a/doc/emacs/building.texi
+++ b/doc/emacs/building.texi
@@ -214,6 +214,7 @@ Select a buffer to be used by next invocation of @code{next-error} and
 @kindex C-x `
 @findex next-error
 @vindex next-error-highlight
+@vindex next-error-highlight-no-select
   To visit errors sequentially, type @w{@kbd{C-x `}}
 (@code{next-error}), or equivalently @kbd{M-g M-n} or @kbd{M-g n}.
 This command can be invoked from any buffer, not just a Compilation
@@ -258,7 +259,9 @@ to skip any messages.
 
   When Emacs visits the locus of an error message, it momentarily
 highlights the relevant source line.  The duration of this highlight
-is determined by the variable @code{next-error-highlight}.
+is determined by the variable @code{next-error-highlight} for the locus
+in the selected buffer, and @code{next-error-highlight-no-select} for
+the locus in non-selected buffers.
 
 @vindex compilation-context-lines
   If the @file{*compilation*} buffer is shown in a window with a left
diff --git a/doc/emacs/custom.texi b/doc/emacs/custom.texi
index f39ce40931c..e7e879065ed 100644
--- a/doc/emacs/custom.texi
+++ b/doc/emacs/custom.texi
@@ -1873,15 +1873,19 @@ You can use a vector for the simple cases too:
   Language and coding systems may cause problems with key bindings for
 non-@acronym{ASCII} characters.  @xref{Init Non-ASCII}.
 
+@findex define-key
   As described in @ref{Local Keymaps}, major modes and minor modes can
 define local keymaps.  These keymaps are constructed when the mode is
-used for the first time in a session.  If you wish to change one of
-these keymaps, you must use the @dfn{mode hook} (@pxref{Hooks}).
+loaded for the first time in a session.  The function @code{define-key}
+can be used to make changes in a specific keymap.  This function can
+also unset keys, when passed @code{nil} as the binding.
 
-@findex define-key
-  For example, Texinfo mode runs the hook @code{texinfo-mode-hook}.
-Here's how you can use the hook to add local bindings for @kbd{C-c n}
-and @kbd{C-c p} in Texinfo mode:
+  Since a mode's keymaps are not constructed until it has been loaded,
+you must delay running code which modifies them, e.g., by putting it
+on a @dfn{mode hook} (@pxref{(Hooks)}).  For example, Texinfo mode
+runs the hook @code{texinfo-mode-hook}.  Here's how you can use the
+hook to add local bindings for @kbd{C-c n} and @kbd{C-c p}, and remove
+the one for @kbd{C-c C-x x} in Texinfo mode:
 
 @example
 (add-hook 'texinfo-mode-hook
@@ -1890,6 +1894,7 @@ and @kbd{C-c p} in Texinfo mode:
                         'backward-paragraph)
             (define-key texinfo-mode-map "\C-cn"
                         'forward-paragraph)))
+            (define-key texinfo-mode-map "\C-c\C-xx" nil)
 @end example
 
 @node Modifier Keys