JVM_IR KT-42020 special IdSignature for some fake override members

compiler/testData/ir/irText/classes/clashingFakeOverrideSignatures.kt

@@ -0,0 +1,67 @@
+// IGNORE_BACKEND_FIR: ANY
+//  ^ TODO decide if we want to fix KT-42020 for FIR as well
+
+open class Base<T> {
+    fun foo(x: T) {}
+    fun foo(y: String) {}
+
+    val T.bar get() = 1
+    val String.bar get() = 2
+}
+
+open class Derived : Base<String>()
+
+class Derived2 : Derived()
+
+fun test(b: Base<String>, d: Derived, d2: Derived2) {
+    b.foo(x = "")
+    b.foo(y = "")
+    d.foo(x = "")
+    d.foo(y = "")
+    d2.foo(x = "")
+    d2.foo(y = "")
+}
+
+
+open class BaseXY<X, Y> {
+    fun foo(x: X, y: String) {}
+    fun foo(x: String, y: Y) {}
+}
+
+class DerivedXY : BaseXY<String, String>()
+
+
+fun outerFun() {
+    open class LocalBase<T> {
+        fun foo(x: T) {}
+        fun foo(y: String) {}
+
+        val T.bar get() = 1
+        val String.bar get() = 2
+    }
+
+    open class LocalDerived : LocalBase<String>()
+
+    class LocalDerived2 : LocalDerived()
+
+    fun test(b: LocalBase<String>, d: LocalDerived, d2: LocalDerived2) {
+        b.foo(x = "")
+        b.foo(y = "")
+        d.foo(x = "")
+        d.foo(y = "")
+        d2.foo(x = "")
+        d2.foo(y = "")
+    }
+}
+
+
+open class Outer<T> {
+    open inner class Inner {
+        fun foo(x: T) {}
+        fun foo(y: String) {}
+    }
+}
+
+class OuterDerived : Outer<String>() {
+    inner class InnerDerived : Inner()
+}