Extensible specificity expressed as a type capability

compiler/testData/diagnostics/tests/platformTypes/intVsIntegerAmbiguity.kt

@@ -9,6 +9,8 @@ public class J {
 
     public interface B {}
     public static B foo(Integer s);
+
+    public static Integer getInteger();
 }
 
 // FILE: k.kt
@@ -25,5 +27,8 @@ fun test(i: Int, ni: Int?) {
     foo(i) : J.A
     J.foo(ni) : J.B
     <!OVERLOAD_RESOLUTION_AMBIGUITY!>foo<!>(ni)
+
+    foo(J.getInteger())
+    J.foo(J.getInteger())
 }
 

compiler/testData/diagnostics/tests/platformTypes/methodCall/overloadingForSubclass.kt

@@ -0,0 +1,30 @@
+// FILE: p/Super.java
+package p;
+
+public interface Super {}
+
+// FILE: p/Sub.java
+package p;
+
+public interface Sub extends Super {}
+
+// FILE: p/Util.java
+
+package p;
+
+public abstract class Util {
+    public abstract void foo(String s, Super sup)
+    public void foo(String s, Sub sub) {}
+}
+
+// FILE: k.kt
+
+import p.*
+
+class C: Util() {
+    override fun foo(s: String, sub: Super) {}
+}
+
+fun foo(sub: Sub) {
+    C().foo("", sub)
+}

compiler/testData/diagnostics/tests/platformTypes/methodCall/overloadingForSubclass.txt

@@ -0,0 +1,12 @@
+package
+
+internal fun foo(/*0*/ sub: p.Sub): kotlin.Unit
+
+internal final class C : p.Util {
+    public constructor C()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ fun foo(/*0*/ s: kotlin.String, /*1*/ sub: p.Super): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun foo(/*0*/ s: kotlin.String!, /*1*/ sub: p.Sub!): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}