[clang-tools-extra] [clang-tidy] Skip system macros in readability-identifier-naming check (PR #132016)

[Carlos Galvez via cfe-commits]

https://github.com/carlosgalvezp updated https://github.com/llvm/llvm-project/pull/132016

>From f57920884bdc225e453fd0d5508494c35d87b3c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Carlos=20G=C3=A1lvez?= <carlos.galvez at zenseact.com>
Date: Wed, 19 Mar 2025 12:28:49 +0000
Subject: [PATCH] [clang-tidy] Skip system macros in
 readability-identifier-naming check

Currently, the check is processing system macros. Most importantly,
it tries to find .clang-tidy files associated with those files, if
the option GetConfigPerFile (on by default) is active.

This is problematic for a number of reasons:

- System macros cannot be acted upon (renamed), so it's wasted work.
- When the main .cpp file includes a system header, clang-tidy tries
  to find the .clang-tidy file for that system header. When that system
  header is a 3rd-party repository, they may have their own .clang-tidy
  file, which may not be compatible with the current version of
  clang-tidy. So, clang-tidy may fail to analyze our main.cpp file,
  only because it includes a 3rd-party system header whose .clang-tidy
  file is incompatible with our clang-tidy binary.

Therefore, skip system macros in this check.

This reduces the amount of unwanted warnings as follows:

On trunk:
Suppressed 11448 warnings (11448 in non-user code).

With this patch:
Suppressed 4824 warnings (4824 in non-user code).

The runtime is pretty much unchanged.
---
 .../clang-tidy/utils/RenamerClangTidyCheck.cpp              | 2 ++
 clang-tools-extra/docs/ReleaseNotes.rst                     | 6 +++---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
index 20853dc00123c..90539eaabbe03 100644
--- a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
@@ -194,6 +194,8 @@ class RenamerClangTidyCheckPPCallbacks : public PPCallbacks {
       return;
     if (SM.isWrittenInCommandLineFile(MacroNameTok.getLocation()))
       return;
+    if (SM.isInSystemHeader(MacroNameTok.getLocation()))
+      return;
     Check->checkMacro(MacroNameTok, Info, SM);
   }
 
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index a489ad9ef937f..a67b1514e387c 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -163,7 +163,7 @@ Changes in existing checks
 
 - Improved :doc:`bugprone-reserved-identifier
   <clang-tidy/checks/bugprone/reserved-identifier>` check by ignoring
-  declarations in system headers.
+  declarations and macros in system headers.
 
 - Improved :doc:`bugprone-signed-char-misuse
   <clang-tidy/checks/bugprone/signed-char-misuse>` check by fixing
@@ -229,8 +229,8 @@ Changes in existing checks
 
 - Improved :doc:`readability-identifier-naming
   <clang-tidy/checks/readability/identifier-naming>` check by ignoring
-  declarations in system headers. The documentation is also improved to
-  differentiate the general options from the specific ones.
+  declarations and macros in system headers. The documentation is also improved
+  to differentiate the general options from the specific ones.
 
 - Improved :doc:`readability-qualified-auto
   <clang-tidy/checks/readability/qualified-auto>` check by adding the option