[clang-tools-extra] [clang-tidy] fix bugprone-sizeof-expression when sizeof expression with template types (PR #115275)

[Congcong Cai via cfe-commits]

https://github.com/HerrCai0907 updated https://github.com/llvm/llvm-project/pull/115275

>From 06fb72b3720e3c457fc672c38258474879006682 Mon Sep 17 00:00:00 2001
From: Congcong Cai <congcongcai0907 at 163.com>
Date: Thu, 7 Nov 2024 15:21:48 +0800
Subject: [PATCH 1/3] [clang-tidy] fix bugprone-sizeof-expression when sizeof
 expression with template types

Fixed: #115175.
`dependent type` are not the same even pointers are the same.
---
 .../clang-tidy/bugprone/SizeofExpressionCheck.cpp            | 4 +++-
 clang-tools-extra/docs/ReleaseNotes.rst                      | 3 ++-
 .../test/clang-tidy/checkers/bugprone/sizeof-expression.cpp  | 5 +++++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
index 628d30ce7f73fe..7269683384f6b5 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
@@ -400,7 +400,9 @@ void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) {
            "suspicious usage of 'sizeof(array)/sizeof(...)';"
            " denominator differs from the size of array elements")
           << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
-    } else if (NumTy && DenomTy && NumTy == DenomTy) {
+    } else if (NumTy && DenomTy && NumTy == DenomTy &&
+               !NumTy->isDependentType()) {
+      // dependent type should not be compared.
       diag(E->getOperatorLoc(),
            "suspicious usage of 'sizeof(...)/sizeof(...)'; both expressions "
            "have the same type")
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index abcdcc25705bf5..4fa8292ff89745 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -175,7 +175,8 @@ Changes in existing checks
 - Improved :doc:`bugprone-sizeof-expression
   <clang-tidy/checks/bugprone/sizeof-expression>` check to find suspicious
   usages of ``sizeof()``, ``alignof()``, and ``offsetof()`` when adding or
-  subtracting from a pointer directly or when used to scale a numeric value.
+  subtracting from a pointer directly or when used to scale a numeric value and
+  fix false positive when sizeof expression with template types.
 
 - Improved :doc:`bugprone-unchecked-optional-access
   <clang-tidy/checks/bugprone/unchecked-optional-access>` to support
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/sizeof-expression.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/sizeof-expression.cpp
index 81efd87345c97e..f3ab78c7355b28 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/sizeof-expression.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/sizeof-expression.cpp
@@ -385,3 +385,8 @@ int ValidExpressions() {
   sum += sizeof(PtrArray) / sizeof(A[0]);
   return sum;
 }
+
+template<class T>
+int ValidateTemplateTypeExpressions(T t) {
+  return sizeof(t.val) / sizeof(t.val[0]);
+}

>From 2df4bc111ad45b014a0a8b5727cade71fa5d9868 Mon Sep 17 00:00:00 2001
From: Congcong Cai <congcongcai0907 at 163.com>
Date: Sat, 9 Nov 2024 21:26:12 +0800
Subject: [PATCH 2/3] Update
 clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp

Co-authored-by: whisperity <whisperity at gmail.com>
---
 clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
index 7269683384f6b5..f3d4c2255d86ec 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
@@ -402,7 +402,7 @@ void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) {
           << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
     } else if (NumTy && DenomTy && NumTy == DenomTy &&
                !NumTy->isDependentType()) {
-      // dependent type should not be compared.
+      // Dependent type should not be compared.
       diag(E->getOperatorLoc(),
            "suspicious usage of 'sizeof(...)/sizeof(...)'; both expressions "
            "have the same type")

>From 4388d530aa24d4e079db1edb72fe1b5d6a1b2937 Mon Sep 17 00:00:00 2001
From: Congcong Cai <congcongcai0907 at 163.com>
Date: Tue, 12 Nov 2024 11:36:16 +0800
Subject: [PATCH 3/3] add issue number in test

---
 .../test/clang-tidy/checkers/bugprone/sizeof-expression.cpp     | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/sizeof-expression.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/sizeof-expression.cpp
index f3ab78c7355b28..5e6f394152e9d1 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/sizeof-expression.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/sizeof-expression.cpp
@@ -386,7 +386,9 @@ int ValidExpressions() {
   return sum;
 }
 
+namespace gh115175 {
 template<class T>
 int ValidateTemplateTypeExpressions(T t) {
   return sizeof(t.val) / sizeof(t.val[0]);
 }
+} // namespace gh115175