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diff --git a/clang/lib/StaticAnalyzer/Checkers/BoolAssignmentChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/BoolAssignmentChecker.cpp
new file mode 100644
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--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/BoolAssignmentChecker.cpp
@@ -0,0 +1,157 @@
+//== BoolAssignmentChecker.cpp - Boolean assignment checker -----*- C++ -*--==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This defines BoolAssignmentChecker, a builtin check in ExprEngine that
+// performs checks for assignment of non-Boolean values to Boolean variables.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/CheckerManager.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+  class BoolAssignmentChecker : public Checker< check::Bind > {
+    mutable llvm::OwningPtr<BuiltinBug> BT;
+    void emitReport(ProgramStateRef state, CheckerContext &C) const;
+  public:
+    void checkBind(SVal loc, SVal val, const Stmt *S, CheckerContext &C) const;
+  };
+} // end anonymous namespace
+
+void BoolAssignmentChecker::emitReport(ProgramStateRef state,
+                                       CheckerContext &C) const {
+  if (ExplodedNode *N = C.addTransition(state)) {
+    if (!BT)
+      BT.reset(new BuiltinBug("Assignment of a non-Boolean value"));    
+    C.EmitReport(new BugReport(*BT, BT->getDescription(), N));
+  }
+}
+
+static bool isBooleanType(QualType Ty) {
+  if (Ty->isBooleanType()) // C++ or C99
+    return true;
+  
+  if (const TypedefType *TT = Ty->getAs<TypedefType>())
+    return TT->getDecl()->getName() == "BOOL"   || // Objective-C
+           TT->getDecl()->getName() == "_Bool"  || // stdbool.h < C99
+           TT->getDecl()->getName() == "Boolean";  // MacTypes.h
+  
+  return false;
+}
+
+void BoolAssignmentChecker::checkBind(SVal loc, SVal val, const Stmt *S,
+                                      CheckerContext &C) const {
+  
+  // We are only interested in stores into Booleans.
+  const TypedValueRegion *TR =
+    dyn_cast_or_null<TypedValueRegion>(loc.getAsRegion());
+  
+  if (!TR)
+    return;
+  
+  QualType valTy = TR->getValueType();
+  
+  if (!isBooleanType(valTy))
+    return;
+  
+  // Get the value of the right-hand side.  We only care about values
+  // that are defined (UnknownVals and UndefinedVals are handled by other
+  // checkers).
+  const DefinedSVal *DV = dyn_cast<DefinedSVal>(&val);
+  if (!DV)
+    return;
+    
+  // Check if the assigned value meets our criteria for correctness.  It must
+  // be a value that is either 0 or 1.  One way to check this is to see if
+  // the value is possibly < 0 (for a negative value) or greater than 1.
+  ProgramStateRef state = C.getState(); 
+  SValBuilder &svalBuilder = C.getSValBuilder();
+  ConstraintManager &CM = C.getConstraintManager();
+  
+  // First, ensure that the value is >= 0.  
+  DefinedSVal zeroVal = svalBuilder.makeIntVal(0, valTy);
+  SVal greaterThanOrEqualToZeroVal =
+    svalBuilder.evalBinOp(state, BO_GE, *DV, zeroVal,
+                          svalBuilder.getConditionType());
+  
+  DefinedSVal *greaterThanEqualToZero =
+    dyn_cast<DefinedSVal>(&greaterThanOrEqualToZeroVal);
+  
+  if (!greaterThanEqualToZero) {
+    // The SValBuilder cannot construct a valid SVal for this condition.
+    // This means we cannot properly reason about it.    
+    return;
+  }
+  
+  ProgramStateRef stateLT, stateGE;
+  llvm::tie(stateGE, stateLT) = CM.assumeDual(state, *greaterThanEqualToZero);
+  
+  // Is it possible for the value to be less than zero?
+  if (stateLT) {
+    // It is possible for the value to be less than zero.  We only
+    // want to emit a warning, however, if that value is fully constrained.
+    // If it it possible for the value to be >= 0, then essentially the
+    // value is underconstrained and there is nothing left to be done.
+    if (!stateGE)
+      emitReport(stateLT, C);
+    
+    // In either case, we are done.
+    return;
+  }
+  
+  // If we reach here, it must be the case that the value is constrained
+  // to only be >= 0.
+  assert(stateGE == state);
+  
+  // At this point we know that the value is >= 0.
+  // Now check to ensure that the value is <= 1.
+  DefinedSVal OneVal = svalBuilder.makeIntVal(1, valTy);
+  SVal lessThanEqToOneVal =
+    svalBuilder.evalBinOp(state, BO_LE, *DV, OneVal,
+                          svalBuilder.getConditionType());
+  
+  DefinedSVal *lessThanEqToOne =
+    dyn_cast<DefinedSVal>(&lessThanEqToOneVal);
+  
+  if (!lessThanEqToOne) {
+    // The SValBuilder cannot construct a valid SVal for this condition.
+    // This means we cannot properly reason about it.    
+    return;
+  }
+  
+  ProgramStateRef stateGT, stateLE;
+  llvm::tie(stateLE, stateGT) = CM.assumeDual(state, *lessThanEqToOne);
+  
+  // Is it possible for the value to be greater than one?
+  if (stateGT) {
+    // It is possible for the value to be greater than one.  We only
+    // want to emit a warning, however, if that value is fully constrained.
+    // If it is possible for the value to be <= 1, then essentially the
+    // value is underconstrained and there is nothing left to be done.
+    if (!stateLE)
+      emitReport(stateGT, C);
+    
+    // In either case, we are done.
+    return;
+  }
+  
+  // If we reach here, it must be the case that the value is constrained
+  // to only be <= 1.
+  assert(stateLE == state);
+}
+
+void ento::registerBoolAssignmentChecker(CheckerManager &mgr) {
+    mgr.registerChecker<BoolAssignmentChecker>();
+}