Interface members are hidden by class members if a type parameter has an effective base other than object

3 files changed, 131 insertions, 1 deletions

diff --git a/mcs/mcs/ecore.cs b/mcs/mcs/ecore.cs
index e24e008e809..b9e4f48c052 100644
--- a/mcs/mcs/ecore.cs
+++ b/mcs/mcs/ecore.cs
@@ -778,8 +778,18 @@ namespace Mono.CSharp {
 					}
 
 					if ((restrictions & MemberLookupRestrictions.InvocableOnly) != 0) {
-						if (member is MethodSpec)
+						if (member is MethodSpec) {
+							//
+							// Interface members that are hidden by class members are removed from the set. This
+							// step only has an effect if T is a type parameter and T has both an effective base 
+							// class other than object and a non-empty effective interface set
+							//
+							var tps = queried_type as TypeParameterSpec;
+							if (tps != null && tps.HasTypeConstraint)
+								members = RemoveHiddenTypeParameterMethods (members);
+
 							return new MethodGroupExpr (members, queried_type, loc);
+						}
 
 						if (!Invocation.IsMemberInvocable (member))
 							continue;
@@ -834,6 +844,54 @@ namespace Mono.CSharp {
 			return null;
 		}
 
+		static IList<MemberSpec> RemoveHiddenTypeParameterMethods (IList<MemberSpec> members)
+		{
+			if (members.Count < 2)
+				return members;
+
+			//
+			// If M is a method, then all non-method members declared in an interface declaration
+			// are removed from the set, and all methods with the same signature as M declared in
+			// an interface declaration are removed from the set
+			//
+
+			bool copied = false;
+			for (int i = 0; i < members.Count; ++i) {
+				var method = members[i] as MethodSpec;
+				if (method == null) {
+					if (!copied) {
+						copied = true;
+						members = new List<MemberSpec> (members);
+					} 
+					
+					members.RemoveAt (i--);
+					continue;
+				}
+
+				if (!method.DeclaringType.IsInterface)
+					continue;
+
+				for (int ii = 0; ii < members.Count; ++ii) {
+					var candidate = members[ii] as MethodSpec;
+					if (candidate == null || !candidate.DeclaringType.IsClass)
+						continue;
+
+					if (!TypeSpecComparer.Override.IsEqual (candidate.Parameters, method.Parameters))
+						continue;
+
+					if (!copied) {
+						copied = true;
+						members = new List<MemberSpec> (members);
+					}
+
+					members.RemoveAt (i--);
+					break;
+				}
+			}
+
+			return members;
+		}
+
 		protected virtual void Error_NegativeArrayIndex (ResolveContext ec, Location loc)
 		{
 			throw new NotImplementedException ();
diff --git a/mcs/tests/gtest-589.cs b/mcs/tests/gtest-589.cs
new file mode 100644
index 00000000000..4599fe2fbd6
--- /dev/null
+++ b/mcs/tests/gtest-589.cs
@@ -0,0 +1,40 @@
+using System;
+
+public class Z : IGenericInterface<Z>
+{
+	public Z Start ()
+	{
+		return this;
+	}
+
+	Z IGenericInterface<Z>.Start ()
+	{
+		throw new ApplicationException ();
+	}
+}
+
+public interface IGenericInterface<T>
+{
+	T Start ();
+}
+
+public class A<T> where T : Z, IGenericInterface<int> 
+{
+	public void SomeOperation (T t)
+	{
+		t.Start ();
+	}
+}
+
+public class C : Z, IGenericInterface<int> 
+{
+	int IGenericInterface<int>.Start ()
+	{
+		throw new NotImplementedException ();
+	}
+
+	public static void Main ()
+	{
+		new A<C> ().SomeOperation (new C ());
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/ver-il-net_4_5.xml b/mcs/tests/ver-il-net_4_5.xml
index 70906f33b41..a317e7489b5 100644
--- a/mcs/tests/ver-il-net_4_5.xml
+++ b/mcs/tests/ver-il-net_4_5.xml
@@ -18346,6 +18346,38 @@
       </method>

     </type>

   </test>

+  <test name="gtest-589.cs">

+    <type name="Z">

+      <method name="Z Start()" attrs="134">

+        <size>10</size>

+      </method>

+      <method name="Z IGenericInterface&lt;Z&gt;.Start()" attrs="481">

+        <size>7</size>

+      </method>

+      <method name="Void .ctor()" attrs="6278">

+        <size>7</size>

+      </method>

+    </type>

+    <type name="A`1[T]">

+      <method name="Void SomeOperation(T)" attrs="134">

+        <size>16</size>

+      </method>

+      <method name="Void .ctor()" attrs="6278">

+        <size>7</size>

+      </method>

+    </type>

+    <type name="C">

+      <method name="Int32 IGenericInterface&lt;int&gt;.Start()" attrs="481">

+        <size>7</size>

+      </method>

+      <method name="Void Main()" attrs="150">

+        <size>17</size>

+      </method>

+      <method name="Void .ctor()" attrs="6278">

+        <size>7</size>

+      </method>

+    </type>

+  </test>

   <test name="gtest-anontype-01.cs">

     <type name="Test">

       <method name="Int32 Main()" attrs="150">