FIR2IR: add fake override generation for built-in classes

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt

@@ -34,6 +34,7 @@ import org.jetbrains.kotlin.fir.types.isSuspendFunctionType
 import org.jetbrains.kotlin.fir.resolve.isKFunctionInvoke
 import org.jetbrains.kotlin.fir.resolve.providers.firProvider
 import org.jetbrains.kotlin.fir.resolve.toSymbol
+import org.jetbrains.kotlin.fir.scopes.unsubstitutedScope
 import org.jetbrains.kotlin.fir.symbols.*
 import org.jetbrains.kotlin.fir.symbols.impl.*
 import org.jetbrains.kotlin.fir.types.*
@@ -163,6 +164,14 @@ class Fir2IrDeclarationStorage(
                 else -> {}
             }
         }
+        val scope = firClass.unsubstitutedScope(session, scopeSession, withForcedTypeCalculator = false)
+        scope.getCallableNames().forEach { callableName ->
+            buildList {
+                fakeOverrideGenerator.generateFakeOverridesForName(
+                    irClass, scope, callableName, firClass, this, realDeclarationSymbols = emptySet()
+                )
+            }.also(fakeOverrideGenerator::bindOverriddenSymbols)
+        }
     }
 
     fun registerFile(firFile: FirFile, irFile: IrFile) {

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/FakeOverrideGenerator.kt

@@ -101,7 +101,7 @@ class FakeOverrideGenerator(
         )
     }
 
-    private fun generateFakeOverridesForName(
+    internal fun generateFakeOverridesForName(
         irClass: IrClass,
         useSiteMemberScope: FirTypeScope,
         name: Name,