[clang-tidy][NFC] add '.clang-tidy' config for clang-tidy project

[vbvictor]

Added .clang-tidy config as discussed in RFC.
Added bugprone, readability, modernize, performance checks that didn't create many warnings.
Fixed minor warnings to make /clang-tidy directory complaint with clang-tidy-20.

Disabled checks will be enabled in future PRs after fixing their warnings.

[llvmbot]

@llvm/pr-subscribers-clang-tidy

Author: Baranov Victor (vbvictor)

Changes

Added .clang-tidy config as discussed in RFC.
Added bugprone checks that didn't create many warnings.
Fixed minor warnings to make /clang-tidy directory complaint with clang-tidy-20.

Disabled checks will be enabled in future PRs after fixing their warnings.

---

Full diff: https://github.com/llvm/llvm-project/pull/147793.diff

3 Files Affected:

• (added) clang-tools-extra/clang-tidy/.clang-tidy (+11)
• (modified) clang-tools-extra/clang-tidy/bugprone/CrtpConstructorAccessibilityCheck.cpp (+2-5)
• (modified) clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp (+5-5)

diff --git a/clang-tools-extra/clang-tidy/.clang-tidy b/clang-tools-extra/clang-tidy/.clang-tidy
new file mode 100644
index 0000000000000..45d1929b6b742
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/.clang-tidy
@@ -0,0 +1,11 @@
+InheritParentConfig: true
+Checks: [
+  bugprone-*
+  -bugprone-assignment-in-if-condition,
+  -bugprone-branch-clone,
+  -bugprone-easily-swappable-parameters,
+  -bugprone-narrowing-conversions,
+  -bugprone-suspicious-stringview-data-usage,
+  -bugprone-unchecked-optional-access,
+  -bugprone-unused-return-value,
+]
diff --git a/clang-tools-extra/clang-tidy/bugprone/CrtpConstructorAccessibilityCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/CrtpConstructorAccessibilityCheck.cpp
index 28e8fe002d575..6565fa3f7c85b 100644
--- a/clang-tools-extra/clang-tidy/bugprone/CrtpConstructorAccessibilityCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/CrtpConstructorAccessibilityCheck.cpp
@@ -129,13 +129,10 @@ void CrtpConstructorAccessibilityCheck::check(
         << HintFriend;
   }
 
-  auto WithFriendHintIfNeeded =
-      [&](const DiagnosticBuilder &Diag,
-          bool NeedsFriend) -> const DiagnosticBuilder & {
+  auto WithFriendHintIfNeeded = [&](const DiagnosticBuilder &Diag,
+                                    bool NeedsFriend) {
     if (NeedsFriend)
       Diag << HintFriend;
-
-    return Diag;
   };
 
   if (!CRTPDeclaration->hasUserDeclaredConstructor()) {
diff --git a/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
index 88d2f2c388d07..88e048e65d4e8 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
@@ -370,16 +370,16 @@ void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) {
         << E->getSourceRange();
   } else if (Result.Nodes.getNodeAs<Stmt>("loop-expr")) {
     auto *SizeofArgTy = Result.Nodes.getNodeAs<Type>("sizeof-arg-type");
-    if (const auto member = dyn_cast<MemberPointerType>(SizeofArgTy))
-      SizeofArgTy = member->getPointeeType().getTypePtr();
+    if (const auto *Member = dyn_cast<MemberPointerType>(SizeofArgTy))
+      SizeofArgTy = Member->getPointeeType().getTypePtr();
 
     const auto *SzOfExpr = Result.Nodes.getNodeAs<Expr>("sizeof-expr");
 
-    if (const auto type = dyn_cast<ArrayType>(SizeofArgTy)) {
+    if (const auto *Type = dyn_cast<ArrayType>(SizeofArgTy)) {
       // check if the array element size is larger than one. If true,
       // the size of the array is higher than the number of elements
-      CharUnits sSize = Ctx.getTypeSizeInChars(type->getElementType());
-      if (!sSize.isOne()) {
+      CharUnits SSize = Ctx.getTypeSizeInChars(Type->getElementType());
+      if (!SSize.isOne()) {
         diag(SzOfExpr->getBeginLoc(),
              "suspicious usage of 'sizeof' in the loop")
             << SzOfExpr->getSourceRange();

[llvmbot]

@llvm/pr-subscribers-clang-tools-extra

Author: Baranov Victor (vbvictor)

Changes

Added .clang-tidy config as discussed in RFC.
Added bugprone checks that didn't create many warnings.
Fixed minor warnings to make /clang-tidy directory complaint with clang-tidy-20.

Disabled checks will be enabled in future PRs after fixing their warnings.

---

Full diff: https://github.com/llvm/llvm-project/pull/147793.diff

3 Files Affected:

• (added) clang-tools-extra/clang-tidy/.clang-tidy (+11)
• (modified) clang-tools-extra/clang-tidy/bugprone/CrtpConstructorAccessibilityCheck.cpp (+2-5)
• (modified) clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp (+5-5)

diff --git a/clang-tools-extra/clang-tidy/.clang-tidy b/clang-tools-extra/clang-tidy/.clang-tidy
new file mode 100644
index 0000000000000..45d1929b6b742
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/.clang-tidy
@@ -0,0 +1,11 @@
+InheritParentConfig: true
+Checks: [
+  bugprone-*
+  -bugprone-assignment-in-if-condition,
+  -bugprone-branch-clone,
+  -bugprone-easily-swappable-parameters,
+  -bugprone-narrowing-conversions,
+  -bugprone-suspicious-stringview-data-usage,
+  -bugprone-unchecked-optional-access,
+  -bugprone-unused-return-value,
+]
diff --git a/clang-tools-extra/clang-tidy/bugprone/CrtpConstructorAccessibilityCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/CrtpConstructorAccessibilityCheck.cpp
index 28e8fe002d575..6565fa3f7c85b 100644
--- a/clang-tools-extra/clang-tidy/bugprone/CrtpConstructorAccessibilityCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/CrtpConstructorAccessibilityCheck.cpp
@@ -129,13 +129,10 @@ void CrtpConstructorAccessibilityCheck::check(
         << HintFriend;
   }
 
-  auto WithFriendHintIfNeeded =
-      [&](const DiagnosticBuilder &Diag,
-          bool NeedsFriend) -> const DiagnosticBuilder & {
+  auto WithFriendHintIfNeeded = [&](const DiagnosticBuilder &Diag,
+                                    bool NeedsFriend) {
     if (NeedsFriend)
       Diag << HintFriend;
-
-    return Diag;
   };
 
   if (!CRTPDeclaration->hasUserDeclaredConstructor()) {
diff --git a/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
index 88d2f2c388d07..88e048e65d4e8 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
@@ -370,16 +370,16 @@ void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) {
         << E->getSourceRange();
   } else if (Result.Nodes.getNodeAs<Stmt>("loop-expr")) {
     auto *SizeofArgTy = Result.Nodes.getNodeAs<Type>("sizeof-arg-type");
-    if (const auto member = dyn_cast<MemberPointerType>(SizeofArgTy))
-      SizeofArgTy = member->getPointeeType().getTypePtr();
+    if (const auto *Member = dyn_cast<MemberPointerType>(SizeofArgTy))
+      SizeofArgTy = Member->getPointeeType().getTypePtr();
 
     const auto *SzOfExpr = Result.Nodes.getNodeAs<Expr>("sizeof-expr");
 
-    if (const auto type = dyn_cast<ArrayType>(SizeofArgTy)) {
+    if (const auto *Type = dyn_cast<ArrayType>(SizeofArgTy)) {
       // check if the array element size is larger than one. If true,
       // the size of the array is higher than the number of elements
-      CharUnits sSize = Ctx.getTypeSizeInChars(type->getElementType());
-      if (!sSize.isOne()) {
+      CharUnits SSize = Ctx.getTypeSizeInChars(Type->getElementType());
+      if (!SSize.isOne()) {
         diag(SzOfExpr->getBeginLoc(),
              "suspicious usage of 'sizeof' in the loop")
             << SzOfExpr->getSourceRange();

[vbvictor]

Added all people that participated in RFC and regular clang-tidy reviewers to see this change.

[EugeneZelenko]

How about adding modernize relevant to currently used C++ standard? Also some of readability checks are useful. Please also consider top-level .clang-tidy file re-formatting.

[vbvictor]

How about adding modernize relevant to currently used C++ standard? Also some of readability checks are useful.

Yes, I will add more and more checks to config. Just started with bugprone as it is the most straightforward improvement. Or do you think we can make it in one go?

Please also consider top-level .clang-tidy file re-formatting.

Noted, will check that.

[EugeneZelenko]

How about adding modernize relevant to currently used C++ standard? Also some of readability checks are useful.

Yes, I will add more and more checks to config. Just started with bugprone as it is the most straightforward improvement. Or do you think we can make it in one go?

Yes, one go is straightforward. However, if preliminary code fixes will be necessary, they should go into separate pull request.

[vbvictor]

Results of running with config (disabled checks that doesn't align with our style)

InheritParentConfig: true
Checks: [
  bugprone-*,
  modernize-*,
  -modernize-avoid-c-arrays,
  -modernize-use-trailing-return-type,
  readability-*,
  -readability-braces-around-statements,
  -readability-identifier-length,
  -readability-magic-numbers,
  -readability-implicit-bool-conversion,
  performance-*
]

report.html.txt (delete .txt to view)
report.txt
I will add checks with a couple of warnings and disable others for future PR's.

[EugeneZelenko]

But please wait for other reviewers.

[EugeneZelenko]

Will be good idea to similar Clang-Tidy configuration over other parts of LLVM code base. May be some check warnings will be easy to fix and enforce. I did such cleanups in past (by quite remote :-().

[PiotrZSL]

LGTM