FIR IDE: resolve reference to intersection override member to overridden members

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

@@ -58,6 +58,9 @@ abstract class KtAnalysisSession(final override val token: ValidityToken) : Vali
     fun KtCallableSymbol.getOverriddenSymbols(containingDeclaration: KtClassOrObjectSymbol): List<KtCallableSymbol> =
         symbolDeclarationOverridesProvider.getOverriddenSymbols(this, containingDeclaration)
 
+    fun KtCallableSymbol.getIntersectionOverriddenSymbols(): Collection<KtCallableSymbol> =
+        symbolDeclarationOverridesProvider.getIntersectionOverriddenSymbols(this)
+
     fun KtExpression.getSmartCasts(): Collection<KtType> = smartCastProvider.getSmartCastedToTypes(this)
 
     fun KtExpression.getImplicitReceiverSmartCasts(): Collection<ImplicitReceiverSmartCast> =

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

@@ -7,7 +7,6 @@ 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() {
@@ -19,5 +18,9 @@ abstract class KtSymbolDeclarationOverridesProvider : KtAnalysisSessionComponent
         containingDeclaration: KtClassOrObjectSymbol
     ): List<KtCallableSymbol>
 
-    //abstract fun getOverriddenSymbols(callableSymbol: KtCallableSymbol, containingDeclaration: KtClassOrObjectSymbol): List<KtCallableSymbol>
+    /**
+     * If [symbol] origin is [org.jetbrains.kotlin.idea.frontend.api.symbols.KtSymbolOrigin.INTERSECTION_OVERRIDE]
+     * Then returns the symbols which [symbol] overrides, otherwise empty collection
+     */
+    abstract fun getIntersectionOverriddenSymbols(symbol: KtCallableSymbol): Collection<KtCallableSymbol>
 }

idea/idea-frontend-api/src/org/jetbrains/kotlin/idea/frontend/api/symbols/KtSymbol.kt

@@ -42,5 +42,17 @@ enum class KtSymbolOrigin {
      */
     JAVA,
 
-    SAM_CONSTRUCTOR
+    SAM_CONSTRUCTOR,
+
+    /**
+     * Consider the following code:
+     * ```
+     * interface A { fun x() }
+     * interface B { fun x() }
+     *
+     * interface C : A, B
+     * ```
+     * The intersection of functions A.foo & B.foo will create a function C.foo which will be marked with [INTERSECTION_OVERRIDE]
+     */
+    INTERSECTION_OVERRIDE,
 }