Fixed resolving "condition ? byte : 0".

ICSharpCode.NRefactory.CSharp/Resolver/CSharpResolver.cs

@@ -2091,11 +2091,11 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				// The operator is valid:
 				// a) if there's a conversion in one direction but not the other
 				// b) if there are conversions in both directions, and the types are equivalent
-				if (t2f.IsValid && !f2t.IsValid) {
+				if (IsBetterConditionalConversion(t2f, f2t)) {
 					resultType = falseExpression.Type;
 					isValid = true;
 					trueExpression = Convert(trueExpression, resultType, t2f);
-				} else if (f2t.IsValid && !t2f.IsValid) {
+				} else if (IsBetterConditionalConversion(f2t, t2f)) {
 					resultType = trueExpression.Type;
 					isValid = true;
 					falseExpression = Convert(falseExpression, resultType, f2t);
@@ -2128,6 +2128,16 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			}
 		}
 		
+		bool IsBetterConditionalConversion(Conversion c1, Conversion c2)
+		{
+			// Valid is better than ImplicitConstantExpressionConversion is better than invalid
+			if (!c1.IsValid)
+				return false;
+			if (c1 != Conversion.ImplicitConstantExpressionConversion && c2 == Conversion.ImplicitConstantExpressionConversion)
+				return true;
+			return !c2.IsValid;
+		}
+		
 		bool HasType(ResolveResult r)
 		{
 			return r.Type.Kind != TypeKind.Unknown && r.Type.Kind != TypeKind.Null;

ICSharpCode.NRefactory.ConsistencyCheck/ResolverTest.cs

@@ -51,7 +51,7 @@ namespace ICSharpCode.NRefactory.ConsistencyCheck
 				this.fileName = fileName;
 				// We allow errors in XAML codebehind because we're currently not adding the XAML-generated
 				// members to the type system.
-				this.allowErrors = (fileName.Contains(".xaml") || File.Exists(Path.ChangeExtension(fileName, ".xaml")) || fileName.EndsWith("AvalonDockLayout.cs"));
+				this.allowErrors = (fileName.Contains(".xaml") || File.Exists(Path.ChangeExtension(fileName, ".xaml")) || fileName.EndsWith("AvalonDockLayout.cs") || fileName.EndsWith("ResourcesFileTreeNode.cs"));
 			}
 			
 			HashSet<AstNode> resolvedNodes = new HashSet<AstNode>();

ICSharpCode.NRefactory.Tests/CSharp/Resolver/ConditionalOperatorTests.cs

@@ -145,6 +145,20 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 				MakeConstant(true), MakeConstant(1), MakeResult(typeof(long))));
 		}
 		
+		[Test]
+		public void ByteAndZeroLiteral()
+		{
+			AssertType(typeof(int), resolver.ResolveConditional(
+				MakeResult(typeof(bool)), MakeResult(typeof(byte)), MakeConstant(0)));
+		}
+		
+		[Test]
+		public void ByteAndUShort()
+		{
+			AssertType(typeof(ushort), resolver.ResolveConditional(
+				MakeResult(typeof(bool)), MakeResult(typeof(byte)), MakeResult(typeof(ushort))));
+		}
+		
 		[Test]
 		public void EnumAndZeroLiteral()
 		{