[Mono-bugs] [Bug 74773][Nor] New - casting to interface doesn't pick up overridden methods

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Changed by vgough@pobox.com.

http://bugzilla.ximian.com/show_bug.cgi?id=74773

--- shadow/74773	2005-04-29 18:49:58.000000000 -0400
+++ shadow/74773.tmp.14791	2005-04-29 18:49:58.000000000 -0400
@@ -0,0 +1,93 @@
+Bug#: 74773
+Product: Mono: Compilers
+Version: 1.1
+OS: 
+OS Details: Suse 9.2
+Status: NEW   
+Resolution: 
+Severity: 
+Priority: Normal
+Component: C#
+AssignedTo: mono-bugs@ximian.com                            
+ReportedBy: vgough@pobox.com               
+QAContact: mono-bugs@ximian.com
+TargetMilestone: ---
+URL: 
+Cc: 
+Summary: casting to interface doesn't pick up overridden methods
+
+Description of Problem:   
+  
+An interface hierarchy seems to confuse mcs.  It proceeds without any errors, but  
+seems to generate incorrect code.  A derived class's overridden method is not called  
+when it should be.  I've reduced the problem to a small test case.  
+   
+Steps to reproduce the problem:   
+Build the following code.  With mcs 1.1.6, it produces:  
+WorkingTest -- Passed  
+FailingTest -- FAILED  
+  
+I believe both tests should succeed -- or if this is not possible for some reason, then   
+mcs should provide an error message.  
+  
+  
+// Some interfaces, one is a superset of the other  
+public interface Node  
+{  
+    int GetStat();  
+}  
+public interface FileNode : Node  
+{  
+    int NotUsed();  
+}  
+  
+// Some basic implementations, one is a superset of the other  
+public class GenericNode : Node  
+{  
+    public virtual int GetStat() { return 0; }  
+}  
+  
+public class GenericFileNode : GenericNode , FileNode  
+{  
+    public virtual int NotUsed() { return -1; }  
+}  
+  
+  
+// Now the ability to override a method depends on if we specify again that we  
+// implement an interface -- although we must because we derive from a class  
+// that does.  
+public class WorkingTest : GenericFileNode , FileNode  
+{  
+    public override int GetStat() { return 42; }  
+}  
+  
+public class FailingTest : GenericFileNode  
+{  
+    // This never gets called, but it builds, so what did we override?!!! 
+    public override int GetStat() { return 42; }  
+}  
+  
+public class TestWrapper  
+{  
+    static bool Test(Node inst, string name)  
+    {  
+        if(inst.GetStat() == 42)  
+        {  
+            System.Console.WriteLine("{0} -- Passed", name);  
+            return true;  
+        } else  
+        {  
+            System.Console.WriteLine("{0} -- FAILED", name);  
+            return false;  
+        }  
+    }  
+  
+    public static int Main()  
+    {  
+        if( Test(new WorkingTest(), "WorkingTest")  
+                && Test(new FailingTest(), "FailingTest") )  
+            return 0; // everything worked  
+        else  
+            return 1;  
+    }  
+}