Fix #3464: Missing cast in string interpolation

ICSharpCode.Decompiler.Tests/TestCases/Pretty/StringInterpolation.cs

@@ -24,6 +24,11 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			Console.WriteLine($"{args.Length,5}");
 		}
 
+		public static void Types()
+		{
+			Console.WriteLine($"{(int)Get<long>()}");
+		}
+
 		public static void ArrayExpansionSpecialCases(object[] args)
 		{
 			Console.WriteLine($"args: {args}");
@@ -142,5 +147,10 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 		{
 			return c + s + s + c;
 		}
+
+		public static TReturn Get<TReturn>()
+		{
+			return default(TReturn);
+		}
 	}
 }

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -3319,22 +3319,28 @@ namespace ICSharpCode.Decompiler.CSharp
 			for (int i = 1; i < block.Instructions.Count; i++)
 			{
 				var call = (Call)block.Instructions[i];
+
+				Interpolation BuildInterpolation(int alignment = 0, string suffix = null)
+				{
+					return new Interpolation(Translate(call.Arguments[1]).ConvertTo(call.GetParameter(1).Type, this, allowImplicitConversion: true), alignment, suffix);
+				}
+
 				switch (call.Method.Name)
 				{
 					case "AppendLiteral":
 						content.Add(new InterpolatedStringText(((LdStr)call.Arguments[1]).Value.Replace("{", "{{").Replace("}", "}}")));
 						break;
 					case "AppendFormatted" when call.Arguments.Count == 2:
-						content.Add(new Interpolation(Translate(call.Arguments[1])));
+						content.Add(BuildInterpolation());
 						break;
 					case "AppendFormatted" when call.Arguments.Count == 3 && call.Arguments[2] is LdStr ldstr:
-						content.Add(new Interpolation(Translate(call.Arguments[1]), suffix: ldstr.Value));
+						content.Add(BuildInterpolation(suffix: ldstr.Value));
 						break;
 					case "AppendFormatted" when call.Arguments.Count == 3 && call.Arguments[2] is LdcI4 ldci4:
-						content.Add(new Interpolation(Translate(call.Arguments[1]), alignment: ldci4.Value));
+						content.Add(BuildInterpolation(alignment: ldci4.Value));
 						break;
 					case "AppendFormatted" when call.Arguments.Count == 4 && call.Arguments[2] is LdcI4 ldci4 && call.Arguments[3] is LdStr ldstr:
-						content.Add(new Interpolation(Translate(call.Arguments[1]), ldci4.Value, ldstr.Value));
+						content.Add(BuildInterpolation(ldci4.Value, ldstr.Value));
 						break;
 					default:
 						throw new NotSupportedException();