[clang] [WIP][Wunsafe-buffer-usage] False positives for & expression indexing constant size array (arr[anything & 0]) (PR #112284)

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<!--LLVM CODE FORMAT COMMENT: {clang-format}-->


:warning: C/C++ code formatter, clang-format found issues in your code. :warning:

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``````````bash
git-clang-format --diff 2ff4c25b7efff64b3b662d0bedcfe7edebcf20b9 81af812176768eb663a09b5ccabe3c7211119b76 --extensions cpp -- clang/lib/Analysis/UnsafeBufferUsage.cpp clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp
``````````

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<details>
<summary>
View the diff from clang-format here.
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``````````diff
diff --git a/clang/lib/Analysis/UnsafeBufferUsage.cpp b/clang/lib/Analysis/UnsafeBufferUsage.cpp
index f80076ee90..017f7f48fe 100644
--- a/clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ b/clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -431,14 +431,16 @@ AST_MATCHER(ArraySubscriptExpr, isSafeArraySubscript) {
       SafeMaskedAccess;
   unsigned int RecLimit = 5;
 
-  SafeMaskedAccess = [&](const Expr *exp, unsigned int RecLimit) -> llvm::APInt {
-    llvm::APInt Max = llvm::APInt::getMaxValue(Finder->getASTContext().getIntWidth(exp->getType()));
+  SafeMaskedAccess = [&](const Expr *exp,
+                         unsigned int RecLimit) -> llvm::APInt {
+    llvm::APInt Max = llvm::APInt::getMaxValue(
+        Finder->getASTContext().getIntWidth(exp->getType()));
     Max.setAllBits();
 
     if (RecLimit == 0)
       return Max;
 
-    //RecLimit--;
+    // RecLimit--;
 
     if (const auto *IntLit = dyn_cast<IntegerLiteral>(exp)) {
       const APInt ArrIdx = IntLit->getValue();
@@ -446,24 +448,26 @@ AST_MATCHER(ArraySubscriptExpr, isSafeArraySubscript) {
     }
 
     if (const auto *BinEx = dyn_cast<BinaryOperator>(exp)) {
-      llvm::APInt LHS = SafeMaskedAccess(BinEx->getLHS()->IgnoreParenCasts(), RecLimit);
-      llvm::APInt RHS = SafeMaskedAccess(BinEx->getRHS()->IgnoreParenCasts(), RecLimit);
-      
-      switch(BinEx->getOpcode()) {
-        case BO_And:
-          LHS = LHS & RHS.getLimitedValue();
-          return LHS;
-        case BO_Or:
-          LHS = LHS | RHS.getLimitedValue();
-          return LHS;
-        case BO_Shl:
-          LHS = LHS << RHS.getLimitedValue();
-          return LHS;
-        case BO_Xor:
-          LHS = LHS ^ RHS.getLimitedValue();
-          return LHS;
-        default:
-          return Max;
+      llvm::APInt LHS =
+          SafeMaskedAccess(BinEx->getLHS()->IgnoreParenCasts(), RecLimit);
+      llvm::APInt RHS =
+          SafeMaskedAccess(BinEx->getRHS()->IgnoreParenCasts(), RecLimit);
+
+      switch (BinEx->getOpcode()) {
+      case BO_And:
+        LHS = LHS & RHS.getLimitedValue();
+        return LHS;
+      case BO_Or:
+        LHS = LHS | RHS.getLimitedValue();
+        return LHS;
+      case BO_Shl:
+        LHS = LHS << RHS.getLimitedValue();
+        return LHS;
+      case BO_Xor:
+        LHS = LHS ^ RHS.getLimitedValue();
+        return LHS;
+      default:
+        return Max;
       }
     }
 
@@ -490,7 +494,8 @@ AST_MATCHER(ArraySubscriptExpr, isSafeArraySubscript) {
       return true;
   } else if (const auto *BinEx = dyn_cast<BinaryOperator>(Node.getIdx())) {
     APInt result = SafeMaskedAccess(Node.getIdx(), RecLimit);
-    if (result.isNonNegative() && result.getLimitedValue() < CATy->getLimitedSize())
+    if (result.isNonNegative() &&
+        result.getLimitedValue() < CATy->getLimitedSize())
       return true;
   }
 
@@ -1198,7 +1203,7 @@ public:
     Handler.handleUnsafeOperation(ASE, IsRelatedToDecl, Ctx);
   }
   SourceLocation getSourceLoc() const override { return ASE->getBeginLoc(); }
-  
+
   DeclUseList getClaimedVarUseSites() const override {
     if (const auto *DRE =
             dyn_cast<DeclRefExpr>(ASE->getBase()->IgnoreParenImpCasts())) {

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https://github.com/llvm/llvm-project/pull/112284