Fix crash in resolver when trying to resolve the warning-id Primitive…

…Expression within PreprocessorWarningDirective.

ICSharpCode.NRefactory.CSharp/Resolver/ResolveVisitor.cs

@@ -464,9 +464,12 @@ CSharpResolver GetPreviouslyScannedContext(AstNode node, out AstNode parent)
 			parent = node;
 			CSharpResolver storedResolver;
 			while (!resolverBeforeDict.TryGetValue(parent, out storedResolver)) {
-				parent = parent.Parent;
-				if (parent == null)
+				AstNode tmp = parent.Parent;
+				if (tmp == null)
 					throw new InvalidOperationException("Could not find a resolver state for any parent of the specified node. Are you trying to resolve a node that is not a descendant of the CSharpAstResolver's root node?");
+				if (tmp.NodeType == NodeType.Whitespace)
+					return resolver; // special case: resolve expression within preprocessor directive
+				parent = tmp;
 			}
 			return storedResolver;
 		}

ICSharpCode.NRefactory.ConsistencyCheck/ResolverTest.cs

@@ -92,7 +92,9 @@ public virtual void Validate(CSharpAstResolver resolver, SyntaxTree syntaxTree)
 			{
 				foreach (AstNode node in syntaxTree.DescendantsAndSelf.Except(resolvedNodes.Keys)) {
 					if (!CSharpAstResolver.IsUnresolvableNode(node)) {
-						Console.WriteLine("Forgot to resolve " + node);
+						if (!node.Ancestors.Any(a => a is PreProcessorDirective)) {
+							Console.WriteLine("Forgot to resolve " + node);
+						}
 					}
 				}
 				foreach (var pair in resolvedNodes) {