fix Issue 8221 - typeof(null) rejected as return type for covariant o…

…verrides
dlang · Jun 12, 2012 · bc55af9 · bc55af9
1 parent 8fa7bdd
commit bc55af9
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diff --git a/src/mtype.c b/src/mtype.c
@@ -5132,6 +5132,8 @@ int Type::covariant(Type *t, StorageClass *pstc)
     }
     else if (t1n->ty == t2n->ty && t1n->implicitConvTo(t2n))
         goto Lcovariant;
+    else if (t1n->ty == Tnull && t1n->implicitConvTo(t2n))
+        goto Lcovariant;
   }
     goto Lnotcovariant;
 

diff --git a/test/runnable/nulltype.d b/test/runnable/nulltype.d
@@ -95,13 +95,35 @@ void test7278()
     Foo7278!null b;
 }
 
+/**********************************************/
+// 8221
+
+class A8221
+{
+    A8221 foo() { return this; }
+}
+class B8221: A8221
+{
+    override typeof(null) foo() { return null; } // error
+}
+void test8221()
+{
+    auto a = new A8221();
+    assert(a.foo() is a);
+    auto b = new B8221();
+    assert(b.foo() is null);
+    a = b;
+    assert(a.foo() is null);
+}
+
 /**********************************************/
 
 int main()
 {
     test1();
     test2();
     test7278();
+    test8221();
 
     printf("Success\n");
     return 0;