Values equality no more provides guarantee for their types equality (for open types or types with overridden equals) #KT-11280 Fixed

compiler/testData/diagnostics/tests/smartCasts/fakeSmartCastOnEquality.kt

@@ -0,0 +1,95 @@
+abstract class Base {
+    override fun equals(other: Any?) = other is Base
+}
+
+class Derived1 : Base() {
+    fun foo() {}
+}
+
+class Derived2 : Base()
+
+fun check(x1: Derived1, x: Base) {
+    if (x1 == x) {
+        // Smart cast here will provoke CCA
+        x.<!UNRESOLVED_REFERENCE!>foo<!>()
+    }
+    if (x1 === x) {
+        // OK
+        <!DEBUG_INFO_SMARTCAST!>x<!>.foo()
+    }
+    if (x1 !== x) {} else {
+        // OK
+        <!DEBUG_INFO_SMARTCAST!>x<!>.foo()
+    }
+}
+
+class FinalClass { // <-- 'equals' on instances of this class is useful for smart casts
+    fun use() {}
+
+    fun equals(x: Int): Boolean = x > 42
+}
+
+fun foo(x: FinalClass?, y: Any) {
+    if (x == y) {
+        // OK
+        <!DEBUG_INFO_SMARTCAST!>x<!>.hashCode()
+        // OK
+        <!DEBUG_INFO_SMARTCAST!>y<!>.use()
+    }
+    when (x) {
+        // OK (equals from FinalClass)
+        y -> <!DEBUG_INFO_SMARTCAST!>y<!>.use()
+    }
+    when (y) {
+        // ERROR (equals from Any)
+        x -> y.<!UNRESOLVED_REFERENCE!>use<!>()
+    }
+}
+
+open class OpenClass {
+    override fun equals(other: Any?) = other is OpenClass
+}
+
+interface Dummy // should not influence anything
+
+class FinalClass2 : Dummy, OpenClass() { // but here not
+    fun use() {}
+}
+
+fun bar(x: FinalClass2?, y: Any) {
+    if (x == y) {
+        // OK
+        <!DEBUG_INFO_SMARTCAST!>x<!>.hashCode()
+        // ERROR
+        y.<!UNRESOLVED_REFERENCE!>use<!>()
+    }
+}
+
+open class OpenClass2 // and here too
+
+fun bar(x: OpenClass2?, y: Any) {
+    if (x == y) {
+        // OK
+        <!DEBUG_INFO_SMARTCAST!>x<!>.hashCode()
+        // ERROR
+        y.<!UNRESOLVED_REFERENCE!>use<!>()
+    }
+}
+
+sealed class Sealed {
+    override fun equals(other: Any?) = other is Sealed
+
+    class Sealed1 : Sealed() {
+        fun gav() {}
+    }
+
+    object Sealed2 : Sealed()
+
+    fun check(arg: Sealed1) {
+        if (arg == this) {
+            // Smart cast here will provoke CCA
+            this.<!UNRESOLVED_REFERENCE!>gav<!>()
+            <!UNRESOLVED_REFERENCE!>gav<!>()
+        }
+    }
+}