KT-9601, KT-10103:

Chose maximally specific function in callable reference
 #KT-9601 Fixed
 #KT-10103 Fixed

compiler/testData/diagnostics/tests/callableReference/resolve/moreSpecificAmbiguousExtensions.kt

@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+interface IA
+interface IB : IA
+
+fun IA.extFun(x: IB) {}
+fun IB.extFun(x: IA) {}
+
+fun test() {
+    val extFun1 = IA::extFun
+    val extFun2 = IB::<!OVERLOAD_RESOLUTION_AMBIGUITY!>extFun<!>
+}
+
+fun testWithExpectedType() {
+    val extFun_AB_A: IA.(IB) -> Unit = IA::extFun
+    val extFun_AA_B: IA.(IA) -> Unit = IB::<!NONE_APPLICABLE!>extFun<!>
+    val extFun_BB_A: IB.(IB) -> Unit = IA::extFun
+    val extFun_BA_B: IB.(IA) -> Unit = IB::extFun
+    val extFun_BB_B: IB.(IB) -> Unit = IB::<!OVERLOAD_RESOLUTION_AMBIGUITY!>extFun<!>
+}