Remove unnecessary casts in switch tests

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -93,19 +93,21 @@ namespace ICSharpCode.Decompiler.CSharp
 			return astType;
 		}
 		
-		public ExpressionWithResolveResult ConvertConstantValue(ResolveResult rr)
+		public ExpressionWithResolveResult ConvertConstantValue(ResolveResult rr, bool allowImplicitConversion = false)
 		{
 			var expr = astBuilder.ConvertConstantValue(rr);
-			if (expr is NullReferenceExpression && rr.Type.Kind != TypeKind.Null) {
-				expr = new CastExpression(ConvertType(rr.Type), expr);
-			} else {
-				switch (rr.Type.GetDefinition()?.KnownTypeCode) {
-					case KnownTypeCode.SByte:
-					case KnownTypeCode.Byte:
-					case KnownTypeCode.Int16:
-					case KnownTypeCode.UInt16:
-						expr = new CastExpression(new PrimitiveType(KnownTypeReference.GetCSharpNameByTypeCode(rr.Type.GetDefinition().KnownTypeCode)), expr);
-						break;
+			if (!allowImplicitConversion) {
+				if (expr is NullReferenceExpression && rr.Type.Kind != TypeKind.Null) {
+					expr = new CastExpression(ConvertType(rr.Type), expr);
+				} else {
+					switch (rr.Type.GetDefinition()?.KnownTypeCode) {
+						case KnownTypeCode.SByte:
+						case KnownTypeCode.Byte:
+						case KnownTypeCode.Int16:
+						case KnownTypeCode.UInt16:
+							expr = new CastExpression(new PrimitiveType(KnownTypeReference.GetCSharpNameByTypeCode(rr.Type.GetDefinition().KnownTypeCode)), expr);
+							break;
+					}
 				}
 			}
 			var exprRR = expr.Annotation<ResolveResult>();

ICSharpCode.Decompiler/CSharp/StatementBuilder.cs

@@ -96,7 +96,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			} else {
 				value = CSharpPrimitiveCast.Cast(ReflectionHelper.GetTypeCode(type), i, false);
 			}
-			return new CaseLabel(exprBuilder.ConvertConstantValue(new ConstantResolveResult(type, value)));
+			return new CaseLabel(exprBuilder.ConvertConstantValue(new ConstantResolveResult(type, value), allowImplicitConversion: true));
 		}
 		
 		protected internal override Statement VisitSwitchInstruction(SwitchInstruction inst)

ICSharpCode.Decompiler/CSharp/TranslatedExpression.cs

@@ -296,7 +296,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			}
 			var rr = expressionBuilder.resolver.WithCheckForOverflow(checkForOverflow).ResolveCast(targetType, ResolveResult);
 			if (rr.IsCompileTimeConstant && !rr.IsError) {
-				return expressionBuilder.ConvertConstantValue(rr)
+				return expressionBuilder.ConvertConstantValue(rr, allowImplicitConversion)
 					.WithILInstruction(this.ILInstructions);
 			}
 			if (targetType.Kind == TypeKind.Pointer && (0.Equals(ResolveResult.ConstantValue) || 0u.Equals(ResolveResult.ConstantValue))) {