[FIR IDE] Add base implementation of find usages of overrides

idea/idea-frontend-api/src/org/jetbrains/kotlin/idea/frontend/api/KtAnalysisSession.kt

@@ -41,12 +41,14 @@ abstract class KtAnalysisSession(override val token: ValidityToken) : ValidityTo
     protected abstract val symbolProvider: KtSymbolProvider
     protected abstract val callResolver: KtCallResolver
     protected abstract val completionCandidateChecker: KtCompletionCandidateChecker
-
+    protected abstract val symbolDeclarationOverridesProvider: KtSymbolDeclarationOverridesProvider
 
     /// TODO: get rid of
     @Deprecated("Used only in completion now, temporary")
     abstract fun createContextDependentCopy(): KtAnalysisSession
 
+    fun KtCallableSymbol.getOverriddenSymbols(containingDeclaration: KtClassOrObjectSymbol): List<KtCallableSymbol> =
+        symbolDeclarationOverridesProvider.getOverriddenSymbols(this, containingDeclaration)
 
     fun KtExpression.getSmartCasts(): Collection<KtType> = smartCastProvider.getSmartCastedToTypes(this)
 

idea/idea-frontend-api/src/org/jetbrains/kotlin/idea/frontend/api/components/KtSymbolDeclarationOverridesProvider.kt

@@ -0,0 +1,23 @@
+/*
+ * 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.idea.frontend.api.components
+
+import org.jetbrains.kotlin.idea.frontend.api.symbols.KtCallableSymbol
+import org.jetbrains.kotlin.idea.frontend.api.symbols.KtClassOrObjectSymbol
+import org.jetbrains.kotlin.idea.frontend.api.symbols.KtFunctionSymbol
+import org.jetbrains.kotlin.idea.frontend.api.symbols.KtSymbol
+
+abstract class KtSymbolDeclarationOverridesProvider : KtAnalysisSessionComponent() {
+    /**
+     * Returns symbols that overridden by requested
+     */
+    abstract fun <T : KtSymbol> getOverriddenSymbols(
+        callableSymbol: T,
+        containingDeclaration: KtClassOrObjectSymbol
+    ): List<KtCallableSymbol>
+
+    //abstract fun getOverriddenSymbols(callableSymbol: KtCallableSymbol, containingDeclaration: KtClassOrObjectSymbol): List<KtCallableSymbol>
+}