diff --git a/.clang-format b/.clang-format
index 7895ada36da8..7198e5c2e854 100644
--- a/.clang-format
+++ b/.clang-format
@@ -1,12 +1,19 @@
-Language: Cpp
-BasedOnStyle: LLVM
+BasedOnStyle: GNU
 AlignEscapedNewlinesLeft: true
+AlignOperands: Align
 AlwaysBreakAfterReturnType: TopLevelDefinitions
 BreakBeforeBinaryOperators: All
 BreakBeforeBraces: GNU
 ColumnLimit: 80
 ContinuationIndentWidth: 2
-ForEachMacros: [FOR_EACH_TAIL, FOR_EACH_TAIL_SAFE]
+IndentPPDirectives: AfterHash
+PPIndentWidth: 1
+ForEachMacros:
+  - FOR_EACH_TAIL
+  - FOR_EACH_TAIL_SAFE
+  - FOR_EACH_LIVE_BUFFER
+  - ITREE_FOREACH
+  - FOR_EACH_ALIST_VALUE
 IncludeCategories:
   - Regex: '^<config\.h>$'
     Priority: -1
@@ -16,11 +23,26 @@ IncludeCategories:
     Priority: 2
   - Regex: '.*'
     Priority: 3
+WhitespaceSensitiveMacros:
+  - STR
+  - CALL1I
+  - CALL2I
+  - STR_VALUE
 KeepEmptyLinesAtTheStartOfBlocks: false
 MaxEmptyLinesToKeep: 1
 PenaltyBreakBeforeFirstCallParameter: 2000
-SpaceAfterCStyleCast: true
-SpaceBeforeParens: Always
+SpaceAfterCStyleCast: false
+SpaceBeforeParens: Custom
+SpaceBeforeParensOptions:
+  AfterControlStatements: true
+  AfterFunctionDefinitionName: false
+  AfterFunctionDeclarationName: false
+  BeforeNonEmptyParentheses: false
+UseTab: ForIndentation
+---
+Language: Cpp
+---
+Language: ObjC
 
 # Local Variables:
 # mode: yaml
diff --git a/.gitattributes b/.gitattributes
index 439f2114067c..e9ebd37ec5a4 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -43,19 +43,41 @@ build-aux/ltmain.sh -whitespace=blank-at-eof
 admin/Makefile.in -whitespace=blank-at-eol
 src/config.in -whitespace=blank-at-eol
 
+# The following text files use encodings incompatible with UTF-8.
+# They should not be treated as text when diffing, as that could
+# cause the output to mix encodings.
+*.tit -diff
+admin/charsets/mapfiles/cns2ucsdkw.txt -diff
+leim/MISC-DIC/CTLau* -diff
+leim/MISC-DIC/cangjie-table.* -diff
+leim/MISC-DIC/pinyin.map -diff
+leim/MISC-DIC/ziranma.cin -diff
+leim/SKK-DIC/SKK-JISYO.L -diff
+src/msdos.c -diff
+test/lisp/gnus/mm-decode-resources/win1252-multipart.bin -diff
+
 # Some files should not be treated as text when diffing or merging.
+*.bmp binary
 *.cur binary
+*.gif binary
 *.gpg binary
 *.gz binary
 *.icns binary
 *.ico binary
+*.jpg binary
+*.kbx binary
+*.key binary
 *.pbm binary
 *.pdf binary
 *.pif binary
 *.png binary
 *.sig binary
 *.tiff binary
+*.webp binary
+*.zip binary
 etc/e/eterm-color binary
+etc/e/eterm-direct binary
+java/emacs.keystore binary
 
 # Git's builtin diff hunk header styles.
 *.ad[abs] diff=ada
@@ -112,6 +134,10 @@ build-aux/update-subdirs diff=shell
 lib-src/rcs2log diff=shell
 /make-dist diff=shell
 
+# This file contains in-line diffs, which can include trailing
+# whitespace.
+java/INSTALL -whitespace
+
 # Gnulib's git-merge-changelog driver:
 ChangeLog    merge=cl-merge
 
diff --git a/.mailmap b/.mailmap
index 5d80e4aa0821..1e78b3ab6cac 100644
--- a/.mailmap
+++ b/.mailmap
@@ -28,6 +28,7 @@ Arash Esbati <arash@gnu.org> <arash.esbati@gmail.com>
 Arash Esbati <arash@gnu.org> <esbati@gmx.de>
 Artur Malabarba <bruce.connor.am@gmail.com> <am12548@it055607.users.bris.ac.uk>
 Artur Malabarba <bruce.connor.am@gmail.com> Artur Malabarba <address@hidden>
+Basil L. Contovounesios <basil@contovou.net> <contovob@tcd.ie>
 Bastien Guerry <bzg@gnu.org>
 Bastien Guerry <bzg@gnu.org> <bastien1@free.fr>
 Bastien Guerry <bzg@gnu.org> <bzg@altern.org>
@@ -115,6 +116,7 @@ Lars Ingebrigtsen <larsi@gnus.org> <larsi@quimbies.gnus.org>
 Lars Ingebrigtsen <larsi@gnus.org> <larsi@stories.gnus.org>
 Laurence Warne <laurencewarne@gmail.com>
 Lin Sun <lin.sun@zoom.us>
+Liu Hui <liuhui1610@gmail.com> <ilupin@users.noreply.github.com>
 Ludovic Courtès <ludo@gnu.org>
 Luke Lee <luke.yx.lee@gmail.com>
 Martin Rudalics <rudalics@gmx.at>