diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index 0082b2f..275406e 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -476,7 +476,8 @@
     return BT->getKind() >= BuiltinType::Bool &&
            BT->getKind() <= BuiltinType::LongLong;
   if (const TagType *TT = dyn_cast<TagType>(CanonicalType))
-    if (TT->getDecl()->isEnum())
+    // Incomplete enum types are not treated as integer types.
+    if (TT->getDecl()->isEnum() && TT->getDecl()->isDefinition())
       return true;
   if (const VectorType *VT = dyn_cast<VectorType>(CanonicalType))
     return VT->getElementType()->isIntegerType();
@@ -490,8 +491,8 @@
     return BT->getKind() >= BuiltinType::Bool &&
     BT->getKind() <= BuiltinType::LongLong;
   if (const TagType *TT = dyn_cast<TagType>(CanonicalType))
-    if (TT->getDecl()->isEnum())
-      return true;
+    if (TT->getDecl()->isEnum() && TT->getDecl()->isDefinition())
+      return true;  // Complete enum types are integral.
   if (const ASQualType *ASQT = dyn_cast<ASQualType>(CanonicalType))
     return ASQT->getBaseType()->isIntegralType();
   return false;
@@ -593,7 +594,7 @@
     return BT->getKind() >= BuiltinType::Bool &&
            BT->getKind() <= BuiltinType::LongDouble;
   if (const TagType *TT = dyn_cast<TagType>(CanonicalType))
-    return TT->getDecl()->isEnum();
+    return TT->getDecl()->isEnum() && TT->getDecl()->isDefinition();
   if (const VectorType *VT = dyn_cast<VectorType>(CanonicalType))
     return VT->getElementType()->isRealType();
   if (const ASQualType *ASQT = dyn_cast<ASQualType>(CanonicalType))
@@ -617,7 +618,9 @@
   if (const BuiltinType *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() != BuiltinType::Void;
   if (const TagType *TT = dyn_cast<TagType>(CanonicalType)) {
-    if (TT->getDecl()->isEnum())
+    // Enums are scalar types, but only if they are defined.  Incomplete enums
+    // are not treated as scalar types.
+    if (TT->getDecl()->isEnum() && TT->getDecl()->isDefinition())
       return true;
     return false;
   }
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index 1462d3d..a4e8946 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -25,6 +25,12 @@
 Sema::StmtResult Sema::ActOnExprStmt(ExprTy *expr) {
   Expr *E = static_cast<Expr*>(expr);
   assert(E && "ActOnExprStmt(): missing expression");
+  
+  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
+  // void expression for its side effects.  Conversion to void allows any
+  // operand, even incomplete types.
+  
+  // Same thing in for stmt first clause (when expr) and third clause.
   return E;
 }
 
@@ -536,7 +542,7 @@
     
     if (!SecondType->isScalarType()) // C99 6.8.5p2
       return Diag(ForLoc, diag::err_typecheck_statement_requires_scalar,
-               SecondType.getAsString(), Second->getSourceRange());
+                  SecondType.getAsString(), Second->getSourceRange());
   }
   return new ForStmt(First, Second, Third, Body, ForLoc);
 }