[clang-tools-extra] [run-clang-tidy.py] Add option to ignore source files from compilation database (PR #82416)

[via cfe-commits]

https://github.com/duddel created https://github.com/llvm/llvm-project/pull/82416

I added the option `-source-ignore` to the `run-clang-tidy.py` script in the clang-tools-extra.

This option allows for handing over a regex, to ignore matching source files from the compilation database (not run `clang-tidy` on them).

**Why "ignore" instead of "filter"?**
I found it more useful to actively filter out (ignore) source files, rather than the inverse logic. One usually knows where the source files reside and can now easily ignore e.g. the `thirdparty/` directory.

>From a3596bf357ef991abcaef04f8811958c0984d9f6 Mon Sep 17 00:00:00 2001
From: duddel <duddel at users.noreply.github.com>
Date: Tue, 20 Feb 2024 21:11:26 +0100
Subject: [PATCH] add -source-ignore option to run-clang-tidy.py

---
 .../clang-tidy/tool/run-clang-tidy.py             | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/clang-tools-extra/clang-tidy/tool/run-clang-tidy.py b/clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
index 70f8cbcdcb2f11..ba4314dfb50aa1 100755
--- a/clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
+++ b/clang-tools-extra/clang-tidy/tool/run-clang-tidy.py
@@ -300,6 +300,12 @@ def main():
         "the main file of each translation unit are always "
         "displayed.",
     )
+    parser.add_argument(
+        "-source-ignore",
+        default=None,
+        help="Regular expression matching the names of the "
+        "source files from compilation database to ignore.",
+    )
     parser.add_argument(
         "-line-filter",
         default=None,
@@ -462,6 +468,15 @@ def main():
         [make_absolute(entry["file"], entry["directory"]) for entry in database]
     )
 
+    # Remove source file to be ignored from database.
+    if args.source_ignore:
+        try:
+            source_ignore_re = re.compile(args.source_ignore)
+        except:
+            print("Error: unable to compile regex from arg -source-ignore.", file=sys.stderr)
+            sys.exit(1)
+        files = {f for f in files if not source_ignore_re.match(f)}
+
     max_task = args.j
     if max_task == 0:
         max_task = multiprocessing.cpu_count()