From 57fb591a54eab7db65d73e77c632f047bca22c54 Mon Sep 17 00:00:00 2001
From: Ted Kremenek <kremenek@apple.com>
Date: Thu, 4 Aug 2011 22:40:57 +0000
Subject: [PATCH] Fix assertion failure in -Wuninitialized involving no-op
 casts.  Fixes PR 10577.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@136939 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/UninitializedValues.cpp | 24 +++++++++++++++++++-----
 test/SemaCXX/uninit-variables.cpp    | 11 +++++++++++
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/lib/Analysis/UninitializedValues.cpp b/lib/Analysis/UninitializedValues.cpp
index 7df2dc27b8..009922ae92 100644
--- a/lib/Analysis/UninitializedValues.cpp
+++ b/lib/Analysis/UninitializedValues.cpp
@@ -352,13 +352,19 @@ class TransferFunctions : public StmtVisitor<TransferFunctions> {
   /// possible to either silence the warning in some cases, or we
   /// propagate the uninitialized value.
   CastExpr *lastLoad;
+  
+  /// For some expressions, we want to ignore any post-processing after
+  /// visitation.
+  bool skipProcessUses;
+  
 public:
   TransferFunctions(CFGBlockValues &vals, const CFG &cfg,
                     AnalysisContext &ac,
                     UninitVariablesHandler *handler,
                     bool flagBlockUses)
     : vals(vals), cfg(cfg), ac(ac), handler(handler),
-      flagBlockUses(flagBlockUses), lastDR(0), lastLoad(0) {}
+      flagBlockUses(flagBlockUses), lastDR(0), lastLoad(0),
+      skipProcessUses(false) {}
   
   const CFG &getCFG() { return cfg; }
   void reportUninit(const DeclRefExpr *ex, const VarDecl *vd,
@@ -464,8 +470,9 @@ void TransferFunctions::VisitDeclStmt(DeclStmt *ds) {
           // appropriately, but we need to continue to analyze subsequent uses
           // of the variable.
           if (init == lastLoad) {
-            DeclRefExpr *DR =
-              cast<DeclRefExpr>(lastLoad->getSubExpr()->IgnoreParens());
+            DeclRefExpr *DR
+              = cast<DeclRefExpr>(lastLoad->
+                  getSubExpr()->IgnoreParenNoopCasts(ac.getASTContext()));
             if (DR->getDecl() == vd) {
               // int x = x;
               // Propagate uninitialized value, but don't immediately report
@@ -537,6 +544,9 @@ void TransferFunctions::VisitCastExpr(clang::CastExpr *ce) {
       }
     }
   }
+  else if (ce->getCastKind() == CK_NoOp) {
+    skipProcessUses = true;
+  }
   else if (CStyleCastExpr *cse = dyn_cast<CStyleCastExpr>(ce)) {
     if (cse->getType()->isVoidType()) {
       // e.g. (void) x;
@@ -551,8 +561,10 @@ void TransferFunctions::VisitCastExpr(clang::CastExpr *ce) {
 }
 
 void TransferFunctions::Visit(clang::Stmt *s) {
+  skipProcessUses = false;
   StmtVisitor<TransferFunctions>::Visit(s);
-  ProcessUses(s);
+  if (!skipProcessUses)
+    ProcessUses(s);
 }
 
 void TransferFunctions::ProcessUses(Stmt *s) {
@@ -568,7 +580,9 @@ void TransferFunctions::ProcessUses(Stmt *s) {
     // If we reach here, we have seen a load of an uninitialized value
     // and it hasn't been casted to void or otherwise handled.  In this
     // situation, report the incident.
-    DeclRefExpr *DR = cast<DeclRefExpr>(lastLoad->getSubExpr()->IgnoreParens());
+    DeclRefExpr *DR =
+      cast<DeclRefExpr>(lastLoad->getSubExpr()->
+                          IgnoreParenNoopCasts(ac.getASTContext()));
     VarDecl *VD = cast<VarDecl>(DR->getDecl());
     reportUninit(DR, VD, isAlwaysUninit(vals[VD]));
     lastLoad = 0;
diff --git a/test/SemaCXX/uninit-variables.cpp b/test/SemaCXX/uninit-variables.cpp
index a850a2f92f..6c5d0068a4 100644
--- a/test/SemaCXX/uninit-variables.cpp
+++ b/test/SemaCXX/uninit-variables.cpp
@@ -118,4 +118,15 @@ void RDar9251392() {
   }
 }
 
+// Test handling of "no-op" casts.
+void test_noop_cast()
+{
+    int x = 1;
+    int y = (int&)x; // no-warning
+}
+
+void test_noop_cast2() {
+    int x; // expected-note {{declared here}} expected-note {{add initialization}}
+    int y = (int&)x; // expected-warning {{uninitialized when used here}}
+}