[IR] Fix classifier equality for Local classes

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/symbols/IrClassifierEqualityChecker.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.ir.symbols
 
 import org.jetbrains.kotlin.descriptors.ClassifierDescriptor
+import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.name.FqName
 
@@ -30,8 +31,22 @@ object FqNameEqualityChecker : IrClassifierEqualityChecker {
             return parentFqName?.child(name)
         }
 
+    private fun isLocalClass(declaration: IrClass): Boolean {
+        var current: IrDeclarationParent? = declaration
+        while (current != null && current !is IrPackageFragment) {
+            if (current is IrDeclarationWithVisibility && current.visibility == Visibilities.LOCAL)
+                return true
+            current = (current as? IrDeclaration)?.parent
+        }
+
+        return false
+    }
+
     private fun checkViaDeclarations(c1: IrSymbolOwner, c2: IrSymbolOwner): Boolean {
         if (c1 is IrClass && c2 is IrClass) {
+            if (isLocalClass(c1) || isLocalClass(c2))
+                return c1 === c2 // Local declarations should be identical
+
             return c1.fqName == c2.fqName
         }