[Mono-bugs] [Bug 74904][Nor] New - gmcs does not unify return types in overridden methods

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Changed by dsilva@ccs.neu.edu.

http://bugzilla.ximian.com/show_bug.cgi?id=74904

--- shadow/74904	2005-05-11 04:00:35.000000000 -0400
+++ shadow/74904.tmp.22610	2005-05-11 04:00:35.000000000 -0400
@@ -0,0 +1,49 @@
+Bug#: 74904
+Product: Mono: Compilers
+Version: 1.0
+OS: 
+OS Details: 
+Status: NEW   
+Resolution: 
+Severity: 
+Priority: Normal
+Component: C#
+AssignedTo: mono-bugs@ximian.com                            
+ReportedBy: dsilva@ccs.neu.edu               
+QAContact: mono-bugs@ximian.com
+TargetMilestone: ---
+URL: 
+Cc: 
+Summary: gmcs does not unify return types in overridden methods
+
+Please fill in this template when reporting a bug, unless you know what you
+are doing.
+Description of Problem:
+
+The two 'map' methods here have the same return type:
+
+  public abstract class List <T> {
+    public delegate U mapping<U>(T obj);
+
+    public abstract List<U> map<U>(mapping<U> f);
+  }
+
+  public class Nil<T> : List<T> {
+    public static Nil<T> nil = new Nil<T>();
+    private Nil() {}
+
+    public override List<U> map<U>(mapping<U> f) {
+      return Nil<U>.nil;
+    }
+  }
+
+but gmcs says:
+
+$ gmcs --version
+Mono C# compiler version 1.1.3.0
+$ gmcs -target:library Test.cs
+Test.cs(12) error CS0508: Nil`1.map(List`1.mapping`1): cannot change return
+type when overriding inherited member
+Test.cs(5): 'List`1.map(List`1.mapping`1)' (name of symbol related to
+previous error
+Compilation failed: 1 error(s), 0 warnings