[FE] Add regression test for KT-57036

compiler/testData/diagnostics/tests/subtyping/kFunctionalCST.kt

@@ -0,0 +1,27 @@
+// INFERENCE_HELPERS
+// ISSUE: KT-57036
+
+abstract class Base(block: String.() -> Int)
+class A(block: String.() -> Int) : Base(block)
+class B(block: String.() -> Int) : Base(block)
+
+fun test_1() {
+    val c = select(::A, ::B)
+    c <!TYPE_MISMATCH!>{ <!UNRESOLVED_REFERENCE!>length<!> }<!>
+    c { it.length }
+}
+
+fun test_2(cond: Boolean) {
+    val c = if (cond) ::A else ::B
+    c <!TYPE_MISMATCH!>{ <!UNRESOLVED_REFERENCE!>length<!> }<!>
+    c { it.length }
+}
+
+fun test_3(cond: Boolean) {
+    val c = when(cond) {
+        true -> ::A
+        false -> ::B
+    }
+    c <!TYPE_MISMATCH!>{ <!UNRESOLVED_REFERENCE!>length<!> }<!>
+    c { it.length }
+}