[clang-tools-extra] [wip][clang-tidy] Add new `bugprone-suspicious-pointer-arithmetics-using-sizeof` (`cert-arr39-c`) check (PR #106061)

[via cfe-commits]

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@@ -0,0 +1,84 @@
+//===--- SuspiciousPointerArithmeticsUsingSizeofCheck.cpp - clang-tidy --===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "SuspiciousPointerArithmeticsUsingSizeofCheck.h"
+#include "../utils/Matchers.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::bugprone {
+
+//static const char *bin_op_bind = "ptr-sizeof-expression";	
+static constexpr llvm::StringLiteral BinOp{"bin-op"};
+static constexpr llvm::StringLiteral PointedType{"pointed-type"};
+static const auto IgnoredType = qualType(anyOf(asString("char"),asString("unsigned char"),asString("signed char"),asString("int8_t"),asString("uint8_t"),asString("std::byte"),asString("const char"),asString("const unsigned char"),asString("const signed char"),asString("const int8_t"),asString("const uint8_t"),asString("const std::byte")));
+static const auto InterestingPointer = pointerType(unless(pointee(IgnoredType)));
+
+SuspiciousPointerArithmeticsUsingSizeofCheck::SuspiciousPointerArithmeticsUsingSizeofCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context) {
+}
+
+void SuspiciousPointerArithmeticsUsingSizeofCheck::registerMatchers(MatchFinder *Finder) {
+    Finder->addMatcher(
+	     expr(anyOf(
+/*                    binaryOperator(hasAnyOperatorName("+","-"),
+                      hasEitherOperand(hasType(pointerType())),
+		      hasEitherOperand(sizeOfExpr(expr())),
+		      unless(allOf(hasLHS(hasType(pointerType())),
+				   hasRHS(hasType(pointerType()))))
+		      ).bind(bin_op_bind),
+		    binaryOperator(hasAnyOperatorName("+=","-="),
+	              hasLHS(hasType(pointerType())),
+		      hasRHS(sizeOfExpr(expr()))
+		      ).bind(bin_op_bind)
+
+		    binaryOperator(hasAnyOperatorName("+=","-=","+","-" ),
+	              hasLHS(hasType(InterestingPointer)),
+		      hasRHS(sizeOfExpr(expr()))).bind(BinOp),
+		    binaryOperator(hasAnyOperatorName("+","-" ),
+	              hasRHS(hasType(InterestingPointer)),
+		      hasLHS(sizeOfExpr(expr()))).bind(BinOp)
+*/		    
+		    binaryOperator(hasAnyOperatorName("+=","-=","+","-" ),
+	              hasLHS(hasType(pointerType(pointee(qualType().bind(PointedType))))),
+		      hasRHS(sizeOfExpr(expr()))).bind(BinOp),
+		    binaryOperator(hasAnyOperatorName("+","-" ),
+	              hasRHS(hasType(pointerType(pointee(qualType().bind(PointedType))))),
+		      hasLHS(sizeOfExpr(expr()))).bind(BinOp)
+            )),
+        this);
+}
+
+static CharUnits getSizeOfType(const ASTContext &Ctx, const Type *Ty) {
+  if (!Ty || Ty->isIncompleteType() || Ty->isDependentType() ||
+      isa<DependentSizedArrayType>(Ty) || !Ty->isConstantSizeType())
+    return CharUnits::Zero();
+  return Ctx.getTypeSizeInChars(Ty);
+}
+
+void SuspiciousPointerArithmeticsUsingSizeofCheck::check(const MatchFinder::MatchResult &Result) {
+    const ASTContext &Ctx = *Result.Context;
+    const BinaryOperator* Matched = Result.Nodes.getNodeAs<BinaryOperator>(BinOp);
----------------
EugeneZelenko wrote:

```suggestion
    const auto* Matched = Result.Nodes.getNodeAs<BinaryOperator>(BinOp);
```

Type is explicitly stated in statement. Same for nex line.

https://github.com/llvm/llvm-project/pull/106061