[generator] Replace hyphens in parameter names (#498)

Context: #464
Context: 7a309c4

Use of [Kotlin][0] can result in some "weird" method names and
parameter names in Java bytecode, in particular names which contain
spaces:

	// Kotlin
	abstract class Example {
	    public fun `method spaces`(`parameter spaces`: Double) {
	    }
	}

Run that through `kotlinc` and `javap`, and...there's a parameter
name with spaces!

	$ kotlinc -java-parameters hello.kt
	$ javap Example.class
	Classfile Example.class
	...
	public abstract class Example
	...
	  public final void method spaces(double);
	    ...
	    MethodParameters:
	      Name                           Flags
	      parameter spaces


...which is a sure fire way to confuse things.

Update `XmlApiImporter.EnsureValidIdentifier()` so that it uses
`IdentifierValidator.CreateValidIdentifier()` (7a309c4) to turn
potentially invalid strings such as `method spaces` into valid C#
identifiers such as `method_spaces`, which also ensures that method
names and constructor names are appropriately fixed.

Additionally, update `XmlApiImporter.CreateParameter()` so that it
now uses `EnsureValidIdentifier()`, ensuring it is consistent with
method and constructor name correction.

[0]: https://kotlinlang.org

Author: jpobst

tools/generator/Java.Interop.Tools.Generator.Importers/XmlApiImporter.cs

@@ -2,6 +2,7 @@
 using System.Linq;
 using System.Text.RegularExpressions;
 using System.Xml.Linq;
+using Java.Interop.Tools.JavaCallableWrappers;
 using MonoDroid.Utils;
 using Xamarin.Android.Tools;
 
@@ -270,7 +271,7 @@ public static Method CreateMethod (GenBase declaringType, XElement elem)
 		public static Parameter CreateParameter (XElement elem)
 		{
 			string managedName = elem.XGetAttribute ("managedName");
-			string name = !string.IsNullOrEmpty (managedName) ? managedName : EnsureValidIdentifer (TypeNameUtilities.MangleName (elem.XGetAttribute ("name")));
+			string name = !string.IsNullOrEmpty (managedName) ? managedName : TypeNameUtilities.MangleName (EnsureValidIdentifer (elem.XGetAttribute ("name")));
 			string java_type = elem.XGetAttribute ("type");
 			string enum_type = elem.Attribute ("enumType") != null ? elem.XGetAttribute ("enumType") : null;
 			string managed_type = elem.Attribute ("managedType") != null ? elem.XGetAttribute ("managedType") : null;
@@ -294,7 +295,7 @@ static string EnsureValidIdentifer (string name)
 			if (string.IsNullOrWhiteSpace (name))
 				return name;
 
-			name = name.Replace ('$', '_');
+			name = IdentifierValidator.CreateValidIdentifier (name);
 
 			if (char.IsNumber (name [0]))
 				name = $"_{name}";

tools/generator/Tests/Unit-Tests/XmlApiImporterTests.cs

@@ -80,6 +80,15 @@ public void CreateMethod_EnsureValidName ()
 			Assert.AreEqual ("_3", klass.Methods [0].Name);
 		}
 
+		[Test]
+		public void CreateMethod_EnsureValidNameHyphen ()
+		{
+			var xml = XDocument.Parse ("<package name=\"com.example.test\" jni-name=\"com/example/test\"><class name=\"test\"><method name=\"-3\" /></class></package>");
+			var klass = XmlApiImporter.CreateClass (xml.Root, xml.Root.Element ("class"));
+
+			Assert.AreEqual ("_3", klass.Methods [0].Name);
+		}
+
 		[Test]
 		public void CreateParameter_EnsureValidName ()
 		{