Fix: Issue #165239 — resolve -Wuninitialized warnings

Author: jimmy2683

clang/lib/Analysis/UninitializedValues.cpp

@@ -62,7 +62,18 @@ static bool isTrackedVar(const VarDecl *vd, const DeclContext *dc) {
     QualType ty = vd->getType();
     if (const auto *RD = ty->getAsRecordDecl())
       return recordIsNotEmpty(RD);
-    return ty->isScalarType() || ty->isVectorType() || ty->isRVVSizelessBuiltinType();
+    
+    bool isArray = ty->isArrayType();
+    bool result = ty->isScalarType() || ty->isVectorType() || ty->isRVVSizelessBuiltinType() || isArray;
+    
+    // Debug output
+    #if DEBUG_LOGGING
+    llvm::errs() << "DEBUG isTrackedVar: " << vd->getNameAsString() 
+                 << " isArray=" << isArray 
+                 << " result=" << result << "\n";
+    #endif
+    
+    return result;
   }
   return false;
 }
@@ -187,8 +198,8 @@ void CFGBlockValues::computeSetOfDeclarations(const DeclContext &dc) {
 static void printVector(const CFGBlock *block, ValueVector &bv,
                         unsigned num) {
   llvm::errs() << block->getBlockID() << " :";
-  for (const auto &i : bv)
-    llvm::errs() << ' ' << i;
+  for (unsigned i = 0, e = bv.size(); i != e; ++i)
+    llvm::errs() << ' ' << bv[i];
   llvm::errs() << " : " << num << '\n';
 }
 #endif
@@ -291,6 +302,7 @@ class ClassifyRefs : public StmtVisitor<ClassifyRefs> {
 public:
   ClassifyRefs(AnalysisDeclContext &AC) : DC(cast<DeclContext>(AC.getDecl())) {}
 
+  void VisitArraySubscriptExpr(ArraySubscriptExpr *ASE);
   void VisitDeclStmt(DeclStmt *DS);
   void VisitUnaryOperator(UnaryOperator *UO);
   void VisitBinaryOperator(BinaryOperator *BO);
@@ -303,13 +315,19 @@ class ClassifyRefs : public StmtVisitor<ClassifyRefs> {
   Class get(const DeclRefExpr *DRE) const {
     llvm::DenseMap<const DeclRefExpr*, Class>::const_iterator I
         = Classification.find(DRE);
-    if (I != Classification.end())
+    if (I != Classification.end()) {
       return I->second;
+    }
 
     const auto *VD = dyn_cast<VarDecl>(DRE->getDecl());
     if (!VD || !isTrackedVar(VD))
       return Ignore;
 
+    // Default to Use instead of Init for arrays - CRITICAL FIX
+    if (VD->getType()->isArrayType()) {
+      return Use;
+    }
+
     return Init;
   }
 };
@@ -331,6 +349,27 @@ static const DeclRefExpr *getSelfInitExpr(VarDecl *VD) {
 void ClassifyRefs::classify(const Expr *E, Class C) {
   // The result of a ?: could also be an lvalue.
   E = E->IgnoreParens();
+  
+  // Handle array subscripts - THE KEY FIX
+  if (const auto *ASE = dyn_cast<ArraySubscriptExpr>(E)) {
+    // For ANY array subscript expression, the base array is being USED
+    // This is the critical fix - don't check C, just mark as Use
+    FindVarResult Var = findVar(ASE->getBase(), DC);
+    if (const VarDecl *VD = Var.getDecl()) {
+      if (VD->getType()->isArrayType()) {
+        // Directly mark the array DeclRefExpr as Use
+        if (const DeclRefExpr *DRE = Var.getDeclRefExpr()) {
+          Classification[DRE] = Use;
+        }
+      }
+    }
+    
+    // Process base and index normally
+    classify(ASE->getBase(), C);
+    Visit(const_cast<Expr*>(ASE->getIdx()));
+    return;
+  }
+  
   if (const auto *CO = dyn_cast<ConditionalOperator>(E)) {
     classify(CO->getTrueExpr(), C);
     classify(CO->getFalseExpr(), C);
@@ -376,6 +415,18 @@ void ClassifyRefs::classify(const Expr *E, Class C) {
   }
 }
 
+void ClassifyRefs::VisitArraySubscriptExpr(ArraySubscriptExpr *ASE) {
+  // Debug output
+  #if DEBUG_LOGGING
+  llvm::errs() << "DEBUG ClassifyRefs::VisitArraySubscriptExpr called\n";
+  #endif
+  
+  // For array subscript expressions, classify the base as a use
+  classify(ASE->getBase(), Use);
+  // Also visit the index expression
+  Visit(ASE->getIdx());
+}
+
 void ClassifyRefs::VisitDeclStmt(DeclStmt *DS) {
   for (auto *DI : DS->decls()) {
     auto *VD = dyn_cast<VarDecl>(DI);
@@ -393,10 +444,27 @@ void ClassifyRefs::VisitBinaryOperator(BinaryOperator *BO) {
   // use.
   if (BO->isCompoundAssignmentOp())
     classify(BO->getLHS(), Use);
-  else if (BO->getOpcode() == BO_Assign || BO->getOpcode() == BO_Comma)
-    classify(BO->getLHS(), Ignore);
+  else if (BO->getOpcode() == BO_Assign || BO->getOpcode() == BO_Comma) {
+    // For array subscript expressions on LHS of assignment, don't classify as use
+    if (isa<ArraySubscriptExpr>(BO->getLHS())) {
+      // Don't classify array base as use when it's being assigned to
+      // But we still need to visit the index expression
+      if (auto *ASE = dyn_cast<ArraySubscriptExpr>(BO->getLHS())) {
+        Visit(ASE->getIdx());
+      }
+    } else {
+      classify(BO->getLHS(), Ignore);
+    }
+    // ALWAYS visit the right-hand side - this is crucial for array subscripts
+    Visit(BO->getRHS());
+  } else {
+    // For all other binary operators, visit both operands normally
+    Visit(BO->getLHS());
+    Visit(BO->getRHS());
+  }
 }
 
+
 void ClassifyRefs::VisitUnaryOperator(UnaryOperator *UO) {
   // Increment and decrement are uses despite there being no lvalue-to-rvalue
   // conversion.
@@ -491,6 +559,7 @@ class TransferFunctions : public StmtVisitor<TransferFunctions> {
   void reportConstRefUse(const Expr *ex, const VarDecl *vd);
   void reportConstPtrUse(const Expr *ex, const VarDecl *vd);
 
+  void VisitArraySubscriptExpr(ArraySubscriptExpr *ASE);
   void VisitBinaryOperator(BinaryOperator *bo);
   void VisitBlockExpr(BlockExpr *be);
   void VisitCallExpr(CallExpr *ce);
@@ -661,10 +730,54 @@ class TransferFunctions : public StmtVisitor<TransferFunctions> {
 
 } // namespace
 
+void TransferFunctions::VisitArraySubscriptExpr(ArraySubscriptExpr *ASE) {
+  // Debug output
+  #if DEBUG_LOGGING
+  llvm::errs() << "DEBUG TransferFunctions::VisitArraySubscriptExpr called\n";
+  #endif
+  
+  // Handle array subscript expressions like arr[i]
+  // Check if the base array variable is uninitialized
+  FindVarResult Var = findVar(ASE->getBase());
+  
+  #if DEBUG_LOGGING
+  llvm::errs() << "DEBUG: FindVar result: " << (Var.getDecl() ? "found" : "not found") << "\n";
+  if (Var.getDecl()) {
+    llvm::errs() << "DEBUG: Variable name: " << Var.getDecl()->getNameAsString() << "\n";
+    llvm::errs() << "DEBUG: Is array type: " << Var.getDecl()->getType()->isArrayType() << "\n";
+  }
+  #endif
+  
+  if (const VarDecl *VD = Var.getDecl()) {
+    if (VD->getType()->isArrayType()) {
+      #if DEBUG_LOGGING
+      llvm::errs() << "DEBUG: Reporting array use for " << VD->getNameAsString() << "\n";
+      #endif
+      reportUse(ASE, VD);
+    }
+  }
+  
+  // Also visit index expression
+  Visit(ASE->getIdx());
+}
+
 void TransferFunctions::reportUse(const Expr *ex, const VarDecl *vd) {
+  #if DEBUG_LOGGING
+  llvm::errs() << "DEBUG TransferFunctions::reportUse for " << vd->getNameAsString() << "\n";
+  #endif
+  
   Value v = vals[vd];
-  if (isUninitialized(v))
+  
+  #if DEBUG_LOGGING
+  llvm::errs() << "DEBUG: Variable " << vd->getNameAsString() << " has value " << v << "\n";
+  #endif
+  
+  if (isUninitialized(v)) {
+    #if DEBUG_LOGGING
+    llvm::errs() << "DEBUG: Reporting uninitialized use of " << vd->getNameAsString() << "\n";
+    #endif
     handler.handleUseOfUninitVariable(vd, getUninitUse(ex, vd, v));
+  }
 }
 
 void TransferFunctions::reportConstRefUse(const Expr *ex, const VarDecl *vd) {