Teach -Wuninitialized-experimental about sizeof().

llvm-svn: 124076

clang/lib/Analysis/UninitializedValuesV2.cpp

@@ -302,6 +302,7 @@ public:
   void VisitUnaryOperator(UnaryOperator *uo);
   void VisitBinaryOperator(BinaryOperator *bo);
   void VisitCastExpr(CastExpr *ce);
+  void VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *se);
 };
 }
 
@@ -435,6 +436,15 @@ void TransferFunctions::VisitCastExpr(clang::CastExpr *ce) {
   Visit(ce->getSubExpr());
 }
 
+void TransferFunctions::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *se) {
+  if (se->isSizeOf()) {
+    if (se->getType()->isConstantSizeType())
+      return;
+    // Handle VLAs.
+    Visit(se->getArgumentExpr());
+  }
+}
+
 //------------------------------------------------------------------------====//
 // High-level "driver" logic for uninitialized values analysis.
 //====------------------------------------------------------------------------//

clang/test/Sema/uninit-variables.c

@@ -180,3 +180,15 @@ MyInt test26() {
   MyInt x; // expected-warning{{use of uninitialized variable 'x'}} expected-note{{add initialization to silence this warning}}
   return x; // expected-note{{variable 'x' is possibly uninitialized when used here}}
 }
+
+// Test handling of sizeof().
+int test27() {
+  struct test_27 { int x; } *y;
+  return sizeof(y->x); // no-warning
+}
+
+int test28() {
+  int len; // expected-warning{{use of uninitialized variable 'len'}} expected-note{{add initialization to silence this warning}}
+  return sizeof(int[len]); // expected-note{{variable 'len' is possibly uninitialized when used here}}
+}
+