Fixed bug in constant expression evaluator

openapi/src/com/intellij/psi/util/IsConstantExpressionVisitor.java

@@ -6,9 +6,13 @@ package com.intellij.psi.util;
 
 import com.intellij.psi.*;
 import com.intellij.psi.tree.IElementType;
+import gnu.trove.THashSet;
+
+import java.util.Set;
 
 public class IsConstantExpressionVisitor extends PsiElementVisitor {
   protected boolean myIsConstant;
+  private Set<PsiVariable> visitedVars = new THashSet<PsiVariable>();
 
   public boolean isConstant() {
     return myIsConstant;
@@ -92,6 +96,10 @@ public class IsConstantExpressionVisitor extends PsiElementVisitor {
       return;
     }
     PsiVariable variable = (PsiVariable)refElement;
+    if (!visitedVars.add(variable)) {
+      myIsConstant = false;
+      return;
+    }
     if (variable instanceof PsiEnumConstant) {
       myIsConstant = true;
       return;

openapi/src/com/intellij/psi/util/PsiUtil.java

@@ -180,6 +180,7 @@ public final class PsiUtil {
   }
 
   public static boolean isConstantExpression(PsiExpression expression) {
+    if (expression == null) return false;
     IsConstantExpressionVisitor visitor = new IsConstantExpressionVisitor();
     expression.accept(visitor);
     return visitor.myIsConstant;