Use FirNamedFunctionSymbol in FirSimpleFunction & its inheritors

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/SessionUtils.kt

@@ -12,7 +12,6 @@ import org.jetbrains.kotlin.fir.resolve.inference.inferenceComponents
 import org.jetbrains.kotlin.fir.scopes.ProcessorAction
 import org.jetbrains.kotlin.fir.scopes.processOverriddenFunctions
 import org.jetbrains.kotlin.fir.scopes.unsubstitutedScope
-import org.jetbrains.kotlin.fir.symbols.impl.FirNamedFunctionSymbol
 import org.jetbrains.kotlin.fir.types.ConeInferenceContext
 import org.jetbrains.kotlin.fir.types.ConeTypeCheckerContext
 
@@ -30,7 +29,6 @@ fun FirSimpleFunction.lowestVisibilityAmongOverrides(
     session: FirSession,
     scopeSession: ScopeSession
 ): Visibility {
-    val symbol = symbol as? FirNamedFunctionSymbol ?: return visibility
     val firTypeScope = containingClass.unsubstitutedScope(session, scopeSession, withForcedTypeCalculator = false)
     var visibility = visibility
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/ConstructorProcessing.kt

@@ -117,7 +117,7 @@ private fun FirTypeAliasSymbol.findSAMConstructorForTypeAlias(
 
     if (type.typeArguments.isEmpty()) return samConstructorForClass
 
-    val namedSymbol = samConstructorForClass.symbol as? FirNamedFunctionSymbol ?: return null
+    val namedSymbol = samConstructorForClass.symbol
 
     val substitutor = prepareSubstitutorForTypeAliasConstructors(
         type,

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirStatusResolver.kt

@@ -75,12 +75,10 @@ class FirStatusResolver(
             buildList<FirCallableMemberDeclaration<*>> {
                 val scope = containingClass.unsubstitutedScope(session, scopeSession, withForcedTypeCalculator = false)
                 val symbol = function.symbol
-                if (symbol is FirNamedFunctionSymbol) {
-                    scope.processFunctionsByName(function.name) {}
-                    scope.processDirectOverriddenFunctionsWithBaseScope(symbol) { overriddenSymbol, _ ->
-                        this += overriddenSymbol.fir
-                        ProcessorAction.NEXT
-                    }
+                scope.processFunctionsByName(function.name) {}
+                scope.processDirectOverriddenFunctionsWithBaseScope(symbol) { overriddenSymbol, _ ->
+                    this += overriddenSymbol.fir
+                    ProcessorAction.NEXT
                 }
             }.mapNotNull {
                 it.status as? FirResolvedDeclarationStatus

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/scopes/impl/FirDelegatedMemberScope.kt

@@ -64,7 +64,7 @@ class FirDelegatedMemberScope(
                     newModality = Modality.OPEN,
                 ).apply {
                     delegatedWrapperData = DelegatedWrapperData(functionSymbol.fir, containingClass.symbol.toLookupTag(), delegateField)
-                }.symbol as FirNamedFunctionSymbol
+                }.symbol
             }
             processor(delegatedSymbol)
         }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/scopes/impl/FirFakeOverrideGenerator.kt

@@ -54,7 +54,7 @@ object FirFakeOverrideGenerator {
     }
 
     private fun createSubstitutionOverrideFunction(
-        fakeOverrideSymbol: FirFunctionSymbol<FirSimpleFunction>,
+        fakeOverrideSymbol: FirNamedFunctionSymbol,
         session: FirSession,
         baseFunction: FirSimpleFunction,
         newDispatchReceiverType: ConeKotlinType?,
@@ -85,7 +85,7 @@ object FirFakeOverrideGenerator {
     }
 
     fun createCopyForFirFunction(
-        newSymbol: FirFunctionSymbol<FirSimpleFunction>,
+        newSymbol: FirNamedFunctionSymbol,
         baseFunction: FirSimpleFunction,
         session: FirSession,
         origin: FirDeclarationOrigin,

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/scopes/impl/FirLocalScope.kt

@@ -34,7 +34,7 @@ class FirLocalScope private constructor(
 
     fun storeFunction(function: FirSimpleFunction): FirLocalScope {
         return FirLocalScope(
-            properties, functions.put(function.name, function.symbol as FirNamedFunctionSymbol), classes
+            properties, functions.put(function.name, function.symbol), classes
         )
     }