Use specialized method for MethodGroupConversion. icsharpcode/NRefactory#21

ICSharpCode.NRefactory.CSharp/Resolver/Conversions.cs

@@ -804,7 +804,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			}
 			var or = rr.PerformOverloadResolution(compilation, args, allowExpandingParams: false, conversions: this);
 			if (or.FoundApplicableCandidate)
-				return Conversion.MethodGroupConversion((IMethod)or.BestCandidate);
+				return Conversion.MethodGroupConversion((IMethod)or.GetBestCandidateWithSubstitutedTypeArguments());
 			else
 				return Conversion.None;
 		}

ICSharpCode.NRefactory.CSharp/Resolver/TypeInference.cs

@@ -513,7 +513,7 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 					                                        allowExtensionMethods: false,
 					                                        allowExpandingParams: false);
 					if (or.FoundApplicableCandidate && or.BestCandidateAmbiguousWith == null) {
-						IType returnType = or.BestCandidate.ReturnType;
+						IType returnType = or.GetBestCandidateWithSubstitutedTypeArguments().ReturnType;
 						MakeLowerBoundInference(returnType, m.ReturnType);
 					}
 				}

ICSharpCode.NRefactory.Tests/CSharp/Resolver/MemberLookupTests.cs

@@ -19,10 +19,10 @@
 using System;
 using System.IO;
 using System.Linq;
-
 using ICSharpCode.NRefactory.CSharp.TypeSystem;
 using ICSharpCode.NRefactory.Semantics;
 using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.NRefactory.TypeSystem.Implementation;
 using NUnit.Framework;
 
 namespace ICSharpCode.NRefactory.CSharp.Resolver
@@ -343,5 +343,25 @@ class Derived<T> : Base where T : Derived<T>
 			Assert.IsFalse(rr.IsError);
 			Assert.AreEqual(0, rr.Member.Parameters.Count);
 		}
+		
+		[Test]
+		public void MethodGroupConversionForGenericMethodHasSpecializedMethod()
+		{
+			string program = @"using System;
+class TestClass {
+	void F<T>(T x) {}
+	public void M() {
+		System.Action<int> f;
+		f = $F$;
+	}
+}";
+			var conversion = GetConversion(program);
+			Assert.IsTrue(conversion.IsValid);
+			Assert.IsTrue(conversion.IsMethodGroupConversion);
+			Assert.IsInstanceOf<SpecializedMethod>(conversion.Method);
+			Assert.AreEqual(
+				new[] { "System.Int32" },
+				((SpecializedMethod)conversion.Method).TypeArguments.Select(t => t.ReflectionName).ToArray());
+		}
 	}
 }