Implemented CSharpResolver.ResolveConditionFalse() for resolving operator false() calls.

Add message to ErrorResolveResult.
Expose CSharpOutputVisitor.PrintPrimitiveValue and CSharpConversions.IsImplicitReferenceConversion/IsBoxingConversion.

ICSharpCode.NRefactory.CSharp/OutputVisitor/CSharpOutputVisitor.cs

@@ -1007,6 +1007,14 @@ namespace ICSharpCode.NRefactory.CSharp
 			EndNode(primitiveExpression);
 		}
 		
+		public static string PrintPrimitiveValue(object val)
+		{
+			StringWriter writer = new StringWriter();
+			CSharpOutputVisitor visitor = new CSharpOutputVisitor(writer, new CSharpFormattingOptions());
+			visitor.WritePrimitiveValue(val);
+			return writer.ToString();
+		}
+		
 		void WritePrimitiveValue(object val)
 		{
 			if (val == null) {

ICSharpCode.NRefactory.CSharp/Resolver/CSharpConversions.cs

@@ -155,7 +155,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				return Conversion.NullLiteralConversion;
 			if (ImplicitReferenceConversion(fromType, toType, 0))
 				return Conversion.ImplicitReferenceConversion;
-			if (BoxingConversion(fromType, toType))
+			if (IsBoxingConversion(fromType, toType))
 				return Conversion.BoxingConversion;
 			if (fromType.Kind == TypeKind.Dynamic)
 				return Conversion.ImplicitDynamicConversion;
@@ -184,7 +184,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				return true;
 			if (ImplicitReferenceConversion(fromType, toType, 0))
 				return true;
-			if (BoxingConversion(fromType, toType) && !NullableType.IsNullable(fromType))
+			if (IsBoxingConversion(fromType, toType) && !NullableType.IsNullable(fromType))
 				return true;
 			if (ImplicitTypeParameterConversion(fromType, toType))
 				return true;
@@ -398,6 +398,11 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		#endregion
 		
 		#region Implicit Reference Conversion
+		public bool IsImplicitReferenceConversion(IType fromType, IType toType)
+		{
+			return ImplicitReferenceConversion(fromType, toType, 0);
+		}
+		
 		bool ImplicitReferenceConversion(IType fromType, IType toType, int subtypeCheckNestingDepth)
 		{
 			// C# 4.0 spec: §6.1.6
@@ -510,7 +515,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		#endregion
 		
 		#region Boxing Conversions
-		bool BoxingConversion(IType fromType, IType toType)
+		public bool IsBoxingConversion(IType fromType, IType toType)
 		{
 			// C# 4.0 spec: §6.1.7
 			fromType = NullableType.GetUnderlyingType(fromType);

ICSharpCode.NRefactory.CSharp/Resolver/CSharpResolver.cs

@@ -2204,6 +2204,27 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			return Convert(input, boolean, c);
 		}
 		
+		/// <summary>
+		/// Converts the negated input to <c>bool</c> using the rules for boolean expressions.
+		/// Computes <c>!(bool)input</c> if the implicit cast to bool is valid; otherwise
+		/// computes <c>input.operator false()</c>.
+		/// </summary>
+		public ResolveResult ResolveConditionFalse(ResolveResult input)
+		{
+			if (input == null)
+				throw new ArgumentNullException("input");
+			IType boolean = compilation.FindType(KnownTypeCode.Boolean);
+			Conversion c = conversions.ImplicitConversion(input, boolean);
+			if (!c.IsValid) {
+				var opFalse = input.Type.GetMethods(m => m.IsOperator && m.Name == "op_False").FirstOrDefault();
+				if (opFalse != null) {
+					c = Conversion.UserDefinedImplicitConversion(opFalse, false);
+					return Convert(input, boolean, c);
+				}
+			}
+			return ResolveUnaryOperator(UnaryOperatorType.Not, Convert(input, boolean, c));
+		}
+		
 		public ResolveResult ResolveConditional(ResolveResult condition, ResolveResult trueExpression, ResolveResult falseExpression)
 		{
 			// C# 4.0 spec §7.14: Conditional operator

ICSharpCode.NRefactory/Semantics/ErrorResolveResult.cs

@@ -35,8 +35,18 @@ namespace ICSharpCode.NRefactory.Semantics
 		{
 		}
 		
+		public ErrorResolveResult(IType type, string message, TextLocation location) : base(type)
+		{
+			this.Message = message;
+			this.Location = location;
+		}
+		
 		public override bool IsError {
 			get { return true; }
 		}
+		
+		public string Message { get; private set; }
+		
+		public TextLocation Location { get; private set; }
 	}
 }