K1/K2: add test confirming correct work of KT-63487 case

Author: mglukhikh

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java

@@ -0,0 +1,23 @@
+FILE: complexTypeUnwrapping2.kt
+    public abstract class AbstractField<out Field : R|AbstractField<Field>|> : R|kotlin/Any| {
+        public constructor<out Field : R|AbstractField<Field>|>(): R|AbstractField<Field>| {
+            super<R|kotlin/Any|>()
+        }
+
+    }
+    public abstract class AbstractElement<Element : R|AbstractElement<Element, Field>|, Field : R|AbstractField<Field>|> : R|kotlin/Any| {
+        public constructor<Element : R|AbstractElement<Element, Field>|, Field : R|AbstractField<Field>|>(): R|AbstractElement<Element, Field>| {
+            super<R|kotlin/Any|>()
+        }
+
+    }
+    public abstract interface ElementOrRef<Element : R|AbstractElement<Element, Field>|, Field : R|AbstractField<Field>|> : R|kotlin/Any| {
+        public abstract val element: R|Element|
+            public get(): R|Element|
+
+    }
+    public final fun elvis(x: R|ElementOrRef<*, *>?|, y: R|ElementOrRef<*, *>?|): R|kotlin/Unit| {
+        lval xElement: R|AbstractElement<out AbstractElement<*, out AbstractField<*>>, out AbstractField<*>>?| = R|<local>/x|?.{ $subj$.R|SubstitutionOverride</ElementOrRef.element: R|CapturedType(*)|>| }
+        lval yElement: R|AbstractElement<out AbstractElement<*, out AbstractField<*>>, out AbstractField<*>>?| = R|<local>/y|?.{ $subj$.R|SubstitutionOverride</ElementOrRef.element: R|CapturedType(*)|>| }
+        lval e: R|AbstractElement<*, out AbstractField<*>>?| = R|<local>/xElement| ?: R|<local>/yElement|
+    }

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java

@@ -0,0 +1,17 @@
+// FIR_IDENTICAL
+// ISSUE: KT-63487
+// FIR_DUMP
+
+abstract class AbstractField<out Field : AbstractField<Field>>
+
+abstract class AbstractElement<Element : AbstractElement<Element, Field>, Field : AbstractField<Field>>
+
+interface ElementOrRef<Element : AbstractElement<Element, Field>, Field : AbstractField<Field>> {
+    val element: Element
+}
+
+fun elvis(x: ElementOrRef<*, *>?, y: ElementOrRef<*, *>?) {
+    val xElement = x?.element
+    val yElement = y?.element
+    val e = xElement ?: yElement
+}