Meta: Provide script to automatically flag bad formatting

Author: https://github.com/BenWiederhake
Commit: https://github.com/SerenityOS/serenity/commit/df4c9b729da
Pull-request: https://github.com/SerenityOS/serenity/pull/3541
Reviewed-by: https://github.com/alimpfard
Reviewed-by: https://github.com/linusg

Meta/lint-clang-format.sh

@@ -0,0 +1,49 @@
+#!/bin/bash
+
+set -e
+
+script_path=$(cd -P -- "$(dirname -- "$0")" && pwd -P)
+cd "${script_path}/.." || exit 1
+
+CLANG_FORMAT=false
+if command -v clang-format-10 >/dev/null 2>&1 ; then
+    CLANG_FORMAT=clang-format-10
+elif command -v clang-format >/dev/null 2>&1 ; then
+    CLANG_FORMAT=clang-format
+    if ! "${CLANG_FORMAT}" --version | grep -qF ' 10.' ; then
+        echo "You are using '$("${CLANG_FORMAT}" --version)', which appears to not be clang-format 10."
+        echo "It is very likely that the resulting changes are not what you wanted."
+    fi
+else
+    echo "clang-format-10 is not available. Either skip this script, or install clang-format-10."
+    echo "(If you install a package 'clang-format', please make sure it's version 10.)"
+    exit 1
+fi
+
+if [ "$#" -eq "1" ] && [ "x--overwrite-inplace" = "x$1" ] ; then
+    true # The only way to run this script.
+else
+    # Note that this branch also covers --help, -h, -help, -?, etc.
+    echo "USAGE: $0 --overwrite-inplace"
+    echo "The argument is necessary to make you aware that this *will* overwrite your local files."
+    exit 1
+fi
+
+echo "Running ${CLANG_FORMAT} ..."
+
+{
+    git ls-files -- \
+        '*.cpp' \
+        '*.h' \
+        ':!:Base' \
+        ':!:Kernel/Arch/i386/CPU.cpp' \
+        ':!:Kernel/FileSystem/ext2_fs.h' \
+        ':!:Libraries/LibC/getopt.cpp' \
+        ':!:Libraries/LibC/syslog.h' \
+        ':!:Libraries/LibCore/puff.h' \
+        ':!:Libraries/LibCore/puff.cpp' \
+        ':!:Libraries/LibELF/exec_elf.h' \
+    || echo "'git ls-files failed!'"
+} | xargs -d'\n' clang-format-10 -style=file -i
+
+echo "Maybe some files have changed. Sorry, but clang-format doesn't indicate what happened."