[Mono-bugs] [Bug 76557][Nor] New - [GMCS] consider base interfaces for CS0309

bugzilla-daemon at bugzilla.ximian.com bugzilla-daemon at bugzilla.ximian.com
Tue Oct 25 14:09:50 EDT 2005

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Changed by atsushi at ximian.com.


--- shadow/76557	2005-10-25 14:09:50.000000000 -0400
+++ shadow/76557.tmp.6466	2005-10-25 14:09:50.000000000 -0400
@@ -0,0 +1,60 @@
+Bug#: 76557
+Product: Mono: Compilers
+Version: 1.1
+OS Details: 
+Status: NEW   
+Priority: Normal
+Component: C#
+AssignedTo: martin at ximian.com                            
+ReportedBy: atsushi at ximian.com               
+QAContact: mono-bugs at ximian.com
+TargetMilestone: ---
+Summary: [GMCS] consider base interfaces for CS0309
+gmcs does not seem to consider base interfaces of the constrained type
+parameters on CS0309 computation. In the code below, K is IBar, thus it
+should be regarded as to implement IFoo. So no CS0309 error should happen.
+(I'm not 100% sure if this understanding is right; it might be regarded as
+a covariant.)
+interface IFoo {}
+interface IBar : IFoo {}
+class Mona<T> where T : IFoo {}
+class Test
+        public Mona<K> GetMona<K> () where K : IBar
+        {
+                return new Mona<K> ();
+        }
+        public static void Main () {}
+Actual Results:
+constraint-baseifaces.cs(8,9): error CS0309: The type `K' must be
+convertible to `IFoo' in order to use it as parameter `T' in the generic
+type or method `Mona`1<T>'
+Compilation failed: 1 error(s), 0 warnings
+Expected Results:
+no error.
+How often does this happen? 
+Additional Information:
+To my understanding, both of this generic type and this generic method are
+(should be) marked as NonVariant.

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