[linker] Mark all TypeConverter if TypeDescriptor is used. Fixes #3372 (#3396)

Moving to reference sources added a few, new converters so the existing
logic to preserve them was not complete.

This update the list of converters, sorted like the reference sources
(RS) for easier reviews.

It also adds:
* a canary test in "dont link" that will fail it the RS code change
or is replaced;
* more complete unit tests to ensure all cases works

https://github.com/xamarin/xamarin-macios/issues/3372

tests/linker/ios/dont link/DontLinkRegressionTests.cs

@@ -8,6 +8,7 @@
 //
 
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 using System.Net;
@@ -107,6 +108,53 @@ namespace DontLink {
 			Assert.True (de.IsReadOnly, "IsReadOnly");
 		}
 
+		[Test]
+		public void TypeDescriptorCanary ()
+		{
+			// this will fail is ReflectTypeDescriptionProvider.cs is modified
+			var rtdp = Type.GetType ("System.ComponentModel.ReflectTypeDescriptionProvider, System");
+			Assert.NotNull (rtdp, "type");
+			var p = rtdp.GetProperty ("IntrinsicTypeConverters", BindingFlags.Static | BindingFlags.NonPublic);
+			Assert.NotNull (p, "property");
+			var ht = (Hashtable) p.GetGetMethod (true).Invoke (null, null);
+			Assert.NotNull (ht, "Hashtable");
+			Assert.That (ht.Count, Is.EqualTo (26), "Count");
+			foreach (var item in ht.Values) {
+				var name = item.ToString ();
+				switch (name) {
+				case "System.ComponentModel.DateTimeOffsetConverter":
+				case "System.ComponentModel.DecimalConverter":
+				case "System.ComponentModel.StringConverter":
+				case "System.ComponentModel.SByteConverter":
+				case "System.ComponentModel.CollectionConverter":
+				case "System.ComponentModel.ReferenceConverter":
+				case "System.ComponentModel.TypeConverter":
+				case "System.ComponentModel.DateTimeConverter":
+				case "System.ComponentModel.UInt64Converter":
+				case "System.ComponentModel.ArrayConverter":
+				case "System.ComponentModel.NullableConverter":
+				case "System.ComponentModel.Int16Converter":
+				case "System.ComponentModel.CultureInfoConverter":
+				case "System.ComponentModel.SingleConverter":
+				case "System.ComponentModel.UInt16Converter":
+				case "System.ComponentModel.GuidConverter":
+				case "System.ComponentModel.DoubleConverter":
+				case "System.ComponentModel.Int32Converter":
+				case "System.ComponentModel.TimeSpanConverter":
+				case "System.ComponentModel.CharConverter":
+				case "System.ComponentModel.Int64Converter":
+				case "System.ComponentModel.BooleanConverter":
+				case "System.ComponentModel.UInt32Converter":
+				case "System.ComponentModel.ByteConverter":
+				case "System.ComponentModel.EnumConverter":
+					break;
+				default:
+					Assert.Fail ($"Unknown type descriptor {name}");
+					break;
+				}
+			}
+		}
+
 #if __TVOS__ || __WATCHOS__
 		void AssertThrowsWrappedNotSupportedException (Action action, string message)
 		{

tests/linker/ios/link sdk/LinkSdkRegressionTest.cs

@@ -493,7 +493,82 @@ namespace LinkSdk {
 		[Test]
 		public void TypeDescriptor_A7793 ()
 		{
-			Assert.NotNull (TypeDescriptor.GetConverter (typeof (bool)));
+			var c = TypeDescriptor.GetConverter (typeof (DateTimeOffset));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("DateTimeOffsetConverter"), "DateTimeOffsetConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (decimal));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("DecimalConverter"), "DecimalConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (string));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("StringConverter"), "StringConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (sbyte));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("SByteConverter"), "SByteConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (Collection<string>));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("CollectionConverter"), "CollectionConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (INSCoding));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("ReferenceConverter"), "ReferenceConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (Type));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("TypeConverter"), "TypeConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (ulong));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("UInt64Converter"), "UInt64Converter");
+
+			c = TypeDescriptor.GetConverter (typeof (int[]));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("ArrayConverter"), "ArrayConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (int?));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("NullableConverter"), "NullableConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (short));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("Int16Converter"), "Int16Converter");
+
+			c = TypeDescriptor.GetConverter (typeof (CultureInfo));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("CultureInfoConverter"), "CultureInfoConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (float));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("SingleConverter"), "SingleConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (ushort));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("UInt16Converter"), "UInt16Converter");
+		
+			c = TypeDescriptor.GetConverter (typeof (Guid));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("GuidConverter"), "GuidConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (double));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("DoubleConverter"), "DoubleConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (int));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("Int32Converter"), "Int32Converter");
+
+			c = TypeDescriptor.GetConverter (typeof (TimeSpan));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("TimeSpanConverter"), "TimeSpanConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (char));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("CharConverter"), "CharConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (long));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("Int64Converter"), "Int64Converter");
+
+			c = TypeDescriptor.GetConverter (typeof (bool));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("BooleanConverter"), "BooleanConverter");
+
+			c = TypeDescriptor.GetConverter (typeof (long));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("Int64Converter"), "Int64Converter");
+
+			c = TypeDescriptor.GetConverter (typeof (uint));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("UInt32Converter"), "UInt32Converter");
+
+			c = TypeDescriptor.GetConverter (typeof (FileShare));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("EnumConverter"), "EnumConverter");
+
+			// special case - it's not in the default list we reflect in dont link tests
+
+			c = TypeDescriptor.GetConverter (typeof (IComponent));
+			Assert.That (c.GetType ().Name, Is.EqualTo ("ComponentConverter"), "ComponentConverter");
 		}
 		
 		[Test]

tools/linker/MobileMarkStep.cs

@@ -303,28 +303,34 @@ namespace Xamarin.Linker.Steps {
 				switch (type.Name) {
 				case "TypeDescriptor":
 					// DefaultConverters are created using Activator.CreateInstance
+					// keep in sync with ReflectTypeDescriptionProvider.cs
 					MarkMethods (GetType ("System", "System.ComponentModel.BooleanConverter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.ByteConverter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.SByteConverter"));
-					MarkMethods (GetType ("System", "System.ComponentModel.StringConverter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.CharConverter"));
-					MarkMethods (GetType ("System", "System.ComponentModel.Int16Converter"));
+					MarkMethods (GetType ("System", "System.ComponentModel.DoubleConverter"));
+					MarkMethods (GetType ("System", "System.ComponentModel.StringConverter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.Int32Converter"));
+					MarkMethods (GetType ("System", "System.ComponentModel.Int16Converter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.Int64Converter"));
+					MarkMethods (GetType ("System", "System.ComponentModel.SingleConverter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.UInt16Converter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.UInt32Converter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.UInt64Converter"));
-					MarkMethods (GetType ("System", "System.ComponentModel.SingleConverter"));
-					MarkMethods (GetType ("System", "System.ComponentModel.DoubleConverter"));
-					MarkMethods (GetType ("System", "System.ComponentModel.DecimalConverter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.TypeConverter"));
-					MarkMethods (GetType ("System", "System.ComponentModel.ArrayConverter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.CultureInfoConverter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.DateTimeConverter"));
-					MarkMethods (GetType ("System", "System.ComponentModel.GuidConverter"));
+					MarkMethods (GetType ("System", "System.ComponentModel.DateTimeOffsetConverter"));
+					MarkMethods (GetType ("System", "System.ComponentModel.DecimalConverter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.TimeSpanConverter"));
+					MarkMethods (GetType ("System", "System.ComponentModel.GuidConverter"));
+					MarkMethods (GetType ("System", "System.ComponentModel.ArrayConverter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.CollectionConverter"));
 					MarkMethods (GetType ("System", "System.ComponentModel.EnumConverter"));
+					MarkMethods (GetType ("System", "System.ComponentModel.ReferenceConverter"));
+					MarkMethods (GetType ("System", "System.ComponentModel.NullableConverter"));
+					// special case - it's not in the Hashtable from the above file (but needed)
+					MarkMethods (GetType ("System", "System.ComponentModel.ComponentConverter"));
 					break;
 				}
 				break;