[generator] Add netcoreapp3.1 support

src/Java.Interop.Tools.JavaCallableWrappers/Java.Interop.Tools.JavaCallableWrappers/IdentifierValidator.cs

@@ -41,6 +41,11 @@ public static string CreateValidIdentifier (string identifier, bool useEncodedRe
 			return validIdentifier.Replace (normalizedIdentifier, "_");
 		}
 
+		public static bool IsValidIdentifier (string identifier)
+		{
+			return !validIdentifier.IsMatch (identifier);
+		}
+
 		// Makes uglier but unique identifiers by encoding each invalid character with its character value
 		static string EncodeReplacement (Match match) => $"_x{(ushort) match.Value [0]}_";
 	}

tools/generator/CodeGenerationOptions.cs

@@ -3,7 +3,9 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using Microsoft.CSharp;
+
+using Java.Interop.Tools.JavaCallableWrappers;
+
 using Xamarin.Android.Binder;
 using Xamarin.AndroidTools.AnnotationSupport;
 
@@ -97,21 +99,29 @@ public string GetOutputName (string s)
 			return GetOutputName (s.Substring (0, idx)) + '<' + String.Join (", ", typeParams.ToArray ()) + '>';
 		}
 
-		CSharpCodeProvider code_provider = new CSharpCodeProvider ();
-
 		public string GetSafeIdentifier (string name)
 		{
+			if (string.IsNullOrEmpty (name))
+				return name;
+
 			// NOTE: "partial" differs in behavior on macOS vs. Windows, Windows reports "partial" as a valid identifier
 			//	This check ensures the same output on both platforms
-			if (name == "partial")
-				return name;
+			switch (name) {
+				case "partial": return name;
+				// `this` isn't in TypeNameUtilities.reserved_keywords; special-case.
+				case "this": return "this_";
+			}
 
 			// In the ideal world, it should not be applied twice.
 			// Sadly that is not true in reality, so we need to exclude non-symbols
 			// when replacing the argument name with a valid identifier.
 			// (ReturnValue.ToNative() takes an argument which could be either an expression or mere symbol.)
-			if (name.LastOrDefault () != ')' && !name.Contains ('.'))
-				name = code_provider.IsValidIdentifier (name) ? name : name + '_';
+			if (name [name.Length-1] != ')' && !name.Contains ('.') && !name.StartsWith ("@")) {
+				if (!IdentifierValidator.IsValidIdentifier (name) ||
+						Array.BinarySearch (TypeNameUtilities.reserved_keywords, name) >= 0) {
+					name = name + "_";
+				}
+			}
 			return name.Replace ('$', '_');
 		}
 

tools/generator/Utilities/TypeNameUtilities.cs

@@ -11,7 +11,7 @@ public static class TypeNameUtilities
 	{
 		// These must be sorted for BinarySearch to work
 		// Missing "this" because it's handled elsewhere as "this_"
-		static string [] reserved_keywords = new [] {
+		internal static string [] reserved_keywords = new [] {
 			"abstract", "as", "base", "bool", "break", "byte", "callback", "case", "catch", "char", "checked", "class", "const",
 			"continue", "decimal", "default", "delegate", "do", "double", "else", "enum", "event", "explicit", "extern", "false",
 			"finally", "fixed", "float", "for", "foreach", "goto", "if", "implicit", "in", "int", "interface", "internal",

tools/generator/generator.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net472</TargetFramework>
+    <TargetFrameworks>net472;netcoreapp3.1</TargetFrameworks>
     <OutputType>Exe</OutputType>
     <DefineConstants>$(DefineConstants);GENERATOR;HAVE_CECIL;JCW_ONLY_TYPE_NAMES</DefineConstants>
     <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>