Allow to pass config file to clang-tidy-diff (#75457)

Adds a `-config-file` command line option that passes on the path of
.`clang-tidy` or custom config file to the `clang-tidy` executable.

clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py

@@ -173,6 +173,12 @@ def main():
         help="checks filter, when not specified, use clang-tidy " "default",
         default="",
     )
+    parser.add_argument(
+        "-config-file",
+        dest="config_file",
+        help="Specify the path of .clang-tidy or custom config file",
+        default="",
+    )
     parser.add_argument("-use-color", action="store_true", help="Use colors in output")
     parser.add_argument(
         "-path", dest="build_path", help="Path used to read a compile command database."
@@ -313,6 +319,8 @@ def main():
         common_clang_tidy_args.append("-fix")
     if args.checks != "":
         common_clang_tidy_args.append("-checks=" + args.checks)
+    if args.config_file != "":
+        common_clang_tidy_args.append("-config-file=" + args.config_file)
     if args.quiet:
         common_clang_tidy_args.append("-quiet")
     if args.build_path is not None:

clang-tools-extra/docs/ReleaseNotes.rst

@@ -119,15 +119,22 @@ Improvements to clang-tidy
 
 - Improved `--dump-config` to print check options in alphabetical order.
 
-- Improved :program:`clang-tidy-diff.py` script. It now returns exit code `1`
-  if any :program:`clang-tidy` subprocess exits with a non-zero code or if
-  exporting fixes fails. It now accepts a directory as a value for
-  `-export-fixes` to export individual yaml files for each compilation unit.
+- Improved :program:`clang-tidy-diff.py` script. 
+    * Return exit code `1` if any :program:`clang-tidy` subprocess exits with
+      a non-zero code or if exporting fixes fails.
+
+    * Accept a directory as a value for `-export-fixes` to export individual
+      yaml files for each compilation unit.
+
+    * Introduce a `-config-file` option that forwards a configuration file to
+      :program:`clang-tidy`. Corresponds to the `--config-file` option in
+      :program:`clang-tidy`.
 
 - Improved :program:`run-clang-tidy.py` script. It now accepts a directory
   as a value for `-export-fixes` to export individual yaml files for each
   compilation unit.
 
+
 New checks
 ^^^^^^^^^^