FIR: move getCallableNames/getClassifierNames from scope to FirContainingNamesAwareScope

compiler/fir/tree/src/org/jetbrains/kotlin/fir/scopes/FirCompositeScope.kt

@@ -11,7 +11,7 @@ import org.jetbrains.kotlin.fir.symbols.impl.FirFunctionSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirVariableSymbol
 import org.jetbrains.kotlin.name.Name
 
-class FirCompositeScope(val scopes: Iterable<FirScope>) : FirScope() {
+class FirCompositeScope(val scopes: Iterable<FirScope>) : FirScope(), FirContainingNamesAwareScope {
 
     override fun processClassifiersByNameWithSubstitution(
         name: Name,
@@ -46,10 +46,10 @@ class FirCompositeScope(val scopes: Iterable<FirScope>) : FirScope() {
     }
 
     override fun getCallableNames(): Set<Name> {
-        return scopes.flatMapTo(mutableSetOf()) { it.getCallableNames() }
+        return scopes.flatMapTo(hashSetOf()) { it.getContainingCallableNamesIfPresent() }
     }
 
     override fun getClassifierNames(): Set<Name> {
-        return scopes.flatMapTo(hashSetOf()) { it.getClassifierNames() }
+        return scopes.flatMapTo(hashSetOf()) { it.getContainingClassifierNamesIfPresent() }
     }
 }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/scopes/FirContainingNamesAwareScope.kt

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.scopes
+
+import org.jetbrains.kotlin.name.Name
+
+interface FirContainingNamesAwareScope {
+    fun getCallableNames(): Set<Name>
+
+    fun getClassifierNames(): Set<Name>
+}
+
+fun FirScope.getContainingCallableNamesIfPresent(): Set<Name> =
+    if (this is FirContainingNamesAwareScope) getCallableNames() else emptySet()
+
+fun FirScope.getContainingClassifierNamesIfPresent(): Set<Name> =
+    if (this is FirContainingNamesAwareScope) getClassifierNames() else emptySet()

compiler/fir/tree/src/org/jetbrains/kotlin/fir/scopes/FirScope.kt

@@ -33,10 +33,6 @@ abstract class FirScope {
     ) {}
 
     open fun mayContainName(name: Name) = true
-
-    open fun getCallableNames(): Set<Name> = emptySet()
-
-    open fun getClassifierNames(): Set<Name> = emptySet()
 }
 
 fun FirTypeScope.processOverriddenFunctionsAndSelf(

compiler/fir/tree/src/org/jetbrains/kotlin/fir/scopes/FirTypeScope.kt

@@ -8,8 +8,9 @@ package org.jetbrains.kotlin.fir.scopes
 import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirFunctionSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirPropertySymbol
+import org.jetbrains.kotlin.name.Name
 
-abstract class FirTypeScope : FirScope() {
+abstract class FirTypeScope : FirScope(), FirContainingNamesAwareScope {
     // Currently, this function and its property brother both have very weak guarantees
     // - It may silently do nothing on symbols originated from different scope instance
     // - It may return the same overridden symbols more then once in case of substitution
@@ -96,5 +97,9 @@ abstract class FirTypeScope : FirScope() {
             propertySymbol: FirPropertySymbol,
             processor: (FirPropertySymbol, Int) -> ProcessorAction
         ): ProcessorAction = ProcessorAction.NEXT
+
+        override fun getCallableNames(): Set<Name> = emptySet()
+
+        override fun getClassifierNames(): Set<Name> = emptySet()
     }
 }