[test] Add regression test for 58809

Check that generic parameters's constraints properly affect the subclass and
interface relationships even when the constraints relate several of the generic
parameters themselves.

diff --git a/mcs/class/corlib/Test/System/TypeTest.cs b/mcs/class/corlib/Test/System/TypeTest.cs
index d03e4c21f2af694ee1ea2bf45fa97fad43341c19..3fe3c3e61b41b109e4b5f0f554618262a36ee7cd 100644 (file)
--- a/mcs/class/corlib/Test/System/TypeTest.cs
+++ b/mcs/class/corlib/Test/System/TypeTest.cs
@@ -3619,6 +3619,38 @@ namespace MonoTests.System
                        public int field;
                }
 
+               [Test]
+               public void IsAssignableFromGenericArgumentsWithConstraints ()
+               {
+                       // Regression test for #58809
+
+                       // Generic Parameters of a gtd should have their
+                       // constraints respected even when those constraints
+                       // are other generic parameters themselves.
+
+                       var ps = typeof (GenericWithParamConstraints<,,>).GetGenericArguments ();
+
+                       var a = ps[0];
+                       var b = ps[1];
+                       var c = ps[2];
+
+                       // Foo<C>
+                       var fooOfC = typeof (Foo<>).MakeGenericType (c);
+
+                       // constraint B : Foo <C>
+                       Assert.IsTrue (fooOfC.IsAssignableFrom (b), "#1");
+
+                       // constraint A : B
+                       Assert.IsTrue (b.IsAssignableFrom (a), "#2");
+
+                       // A : Foo<C> since A : B and B : Foo<C>
+                       Assert.IsTrue (fooOfC.IsAssignableFrom (a), "#3");
+               }
+
+               class GenericWithParamConstraints<A, B, C> where B : Foo<C> where A : B
+               {
+               }
+
                [Test] // Bug #612780
                public void CannotMakeDerivedTypesFromTypedByRef ()
                {