diff --git a/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinToJVMBytecodeCompiler.kt b/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinToJVMBytecodeCompiler.kt
index 888d91c2e7a..da56507ab1d 100644
--- a/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinToJVMBytecodeCompiler.kt
+++ b/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinToJVMBytecodeCompiler.kt
@@ -55,7 +55,7 @@ import org.jetbrains.kotlin.fir.backend.Fir2IrConverter
 import org.jetbrains.kotlin.fir.backend.jvm.FirJvmClassCodegen
 import org.jetbrains.kotlin.fir.builder.RawFirBuilder
 import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
-import org.jetbrains.kotlin.fir.extensions.extensionsService
+import org.jetbrains.kotlin.fir.extensions.oldExtensionsService
 import org.jetbrains.kotlin.fir.extensions.registerExtensions
 import org.jetbrains.kotlin.fir.java.FirJavaModuleBasedSession
 import org.jetbrains.kotlin.fir.java.FirLibrarySession
@@ -327,7 +327,7 @@ object KotlinToJVMBytecodeCompiler {
                     dependenciesInfo, provider, librariesScope,
                     project, environment.createPackagePartProvider(librariesScope)
                 )
-                it.extensionsService.registerExtensions(FirExtensionRegistrar.RegisteredExtensions.EMPTY)
+                it.oldExtensionsService.registerExtensions(FirExtensionRegistrar.RegisteredExtensions.EMPTY)
             }
             val firProvider = (session.firProvider as FirProviderImpl)
             val builder = RawFirBuilder(session, firProvider.kotlinScopeProvider, stubMode = false)
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/collectors/FirDiagnosticsCollector.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/collectors/FirDiagnosticsCollector.kt
index 5c9be8bef7b..42b296897bf 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/collectors/FirDiagnosticsCollector.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/collectors/FirDiagnosticsCollector.kt
@@ -8,7 +8,7 @@ package org.jetbrains.kotlin.fir.analysis.collectors
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.analysis.checkersComponent
 import org.jetbrains.kotlin.fir.analysis.extensions.additionalCheckers
-import org.jetbrains.kotlin.fir.extensions.extensionsService
+import org.jetbrains.kotlin.fir.extensions.oldExtensionsService
 
 object FirDiagnosticsCollector {
     fun create(session: FirSession): AbstractDiagnosticCollector {
@@ -28,6 +28,6 @@ object FirDiagnosticsCollector {
     }
 
     private fun FirSession.registerAdditionalCheckers() {
-        extensionsService.additionalCheckers.forEach(checkersComponent::register)
+        oldExtensionsService.additionalCheckers.forEach(checkersComponent::register)
     }
 }
\ No newline at end of file
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/extensions/FirAdditionalCheckersExtension.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/extensions/FirAdditionalCheckersExtension.kt
index c20ec690bfb..f8d1f1fcee2 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/extensions/FirAdditionalCheckersExtension.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/extensions/FirAdditionalCheckersExtension.kt
@@ -36,14 +36,14 @@ abstract class FirAdditionalCheckersExtension(session: FirSession) : AbstractFir
         get() = Mode.ALL
 }
 
-val FirExtensionsService.additionalCheckers: List<FirAdditionalCheckersExtension> by FirExtensionsService.additionalCheckers()
+val FirOldExtensionsService.additionalCheckers: List<FirAdditionalCheckersExtension> by FirOldExtensionsService.additionalCheckers()
 
-private fun FirExtensionsService.Companion.additionalCheckers(): ReadOnlyProperty<FirExtensionsService, List<FirAdditionalCheckersExtension>> {
+private fun FirOldExtensionsService.Companion.additionalCheckers(): ReadOnlyProperty<FirOldExtensionsService, List<FirAdditionalCheckersExtension>> {
     val accessor = generateAccessor<FirRegisteredExtension<AbstractFirAdditionalCheckersExtension>, AbstractFirAdditionalCheckersExtension>(
         AbstractFirAdditionalCheckersExtension::class
     )
-    return object : ReadOnlyProperty<FirExtensionsService, List<FirAdditionalCheckersExtension>> {
-        override fun getValue(thisRef: FirExtensionsService, property: KProperty<*>): List<FirAdditionalCheckersExtension> {
+    return object : ReadOnlyProperty<FirOldExtensionsService, List<FirAdditionalCheckersExtension>> {
+        override fun getValue(thisRef: FirOldExtensionsService, property: KProperty<*>): List<FirAdditionalCheckersExtension> {
             val extensions = accessor.getValue(thisRef, property)
             @Suppress("UNCHECKED_CAST")
             return extensions.extensionsWithAllMode as List<FirAdditionalCheckersExtension>
diff --git a/compiler/fir/java/src/org/jetbrains/kotlin/fir/java/FirJavaModuleBasedSession.kt b/compiler/fir/java/src/org/jetbrains/kotlin/fir/java/FirJavaModuleBasedSession.kt
index 70d4eee460f..78039e04868 100644
--- a/compiler/fir/java/src/org/jetbrains/kotlin/fir/java/FirJavaModuleBasedSession.kt
+++ b/compiler/fir/java/src/org/jetbrains/kotlin/fir/java/FirJavaModuleBasedSession.kt
@@ -15,7 +15,7 @@ import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.FirSessionBase
 import org.jetbrains.kotlin.fir.FirSessionProvider
 import org.jetbrains.kotlin.fir.analysis.CheckersComponent
-import org.jetbrains.kotlin.fir.extensions.FirExtensionsService
+import org.jetbrains.kotlin.fir.extensions.FirOldExtensionsService
 import org.jetbrains.kotlin.fir.java.deserialization.KotlinDeserializedJvmSymbolsProvider
 import org.jetbrains.kotlin.fir.resolve.FirProvider
 import org.jetbrains.kotlin.fir.resolve.FirSymbolProvider
@@ -122,8 +122,8 @@ class FirLibrarySession private constructor(
         )
 
         registerComponent(
-            FirExtensionsService::class,
-            FirExtensionsService(this)
+            FirOldExtensionsService::class,
+            FirOldExtensionsService(this)
         )
 
         sessionProvider.sessionCache[moduleInfo] = this
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirModuleBasedSession.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirModuleBasedSession.kt
index e3c3f371fe2..77dff5e96f2 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirModuleBasedSession.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirModuleBasedSession.kt
@@ -6,7 +6,7 @@
 package org.jetbrains.kotlin.fir
 
 import org.jetbrains.kotlin.analyzer.ModuleInfo
-import org.jetbrains.kotlin.fir.extensions.FirExtensionsService
+import org.jetbrains.kotlin.fir.extensions.FirOldExtensionsService
 import org.jetbrains.kotlin.fir.resolve.*
 import org.jetbrains.kotlin.fir.resolve.impl.*
 import org.jetbrains.kotlin.fir.scopes.impl.FirDeclaredMemberScopeProvider
@@ -17,7 +17,7 @@ abstract class FirModuleBasedSession(override val moduleInfo: ModuleInfo, sessio
         registerComponent(FirQualifierResolver::class, FirQualifierResolverImpl(this))
         registerComponent(FirTypeResolver::class, FirTypeResolverImpl(this))
         registerComponent(FirDeclaredMemberScopeProvider::class, FirDeclaredMemberScopeProvider())
-        registerComponent(FirExtensionsService::class, FirExtensionsService(this))
+        registerComponent(FirOldExtensionsService::class, FirOldExtensionsService(this))
     }
 }
 
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirClassGenerationExtension.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirClassGenerationExtension.kt
index f0da640701e..416d66e47ec 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirClassGenerationExtension.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirClassGenerationExtension.kt
@@ -43,4 +43,4 @@ abstract class FirClassGenerationExtension(session: FirSession) : FirExtension(s
     fun interface Factory : FirExtension.Factory<FirClassGenerationExtension>
 }
 
-val FirExtensionsService.classGenerationExtensions: FirExtensionsService.ExtensionsAccessor<FirClassGenerationExtension> by FirExtensionsService.registeredExtensions()
+val FirOldExtensionsService.classGenerationExtensions: FirOldExtensionsService.ExtensionsAccessor<FirClassGenerationExtension> by FirOldExtensionsService.registeredExtensions()
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrar.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrar.kt
index 6ae4b3ae23d..ad86fe249c8 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrar.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrar.kt
@@ -57,7 +57,7 @@ abstract class FirExtensionRegistrar {
     }
 }
 
-fun FirExtensionsService.registerExtensions(extensions: FirExtensionRegistrar.RegisteredExtensions) {
+fun FirOldExtensionsService.registerExtensions(extensions: FirExtensionRegistrar.RegisteredExtensions) {
     registerExtensions(FirStatusTransformerExtension::class, extensions.statusTransformerExtensions)
     registerExtensions(FirClassGenerationExtension::class, extensions.classGenerationExtensions)
     registerExtensions(AbstractFirAdditionalCheckersExtension::class, extensions.additionalCheckersExtensions)
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirExtensionsService.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirOldExtensionsService.kt
similarity index 92%
rename from compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirExtensionsService.kt
rename to compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirOldExtensionsService.kt
index a6da2953ae3..db1a598207a 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirExtensionsService.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirOldExtensionsService.kt
@@ -35,14 +35,15 @@ class FirRegisteredExtension<P : FirExtension>(
     }
 }
 
-class FirExtensionsService(
+@Deprecated("")
+class FirOldExtensionsService(
     val session: FirSession
 ) : ComponentArrayOwner<FirExtension, FirRegisteredExtension<*>>(), FirSessionComponent {
     companion object : TypeRegistry<FirExtension, FirRegisteredExtension<*>>() {
-        inline fun <reified P : FirExtension, V : FirRegisteredExtension<P>> registeredExtensions(): ReadOnlyProperty<FirExtensionsService, ExtensionsAccessor<P>> {
+        inline fun <reified P : FirExtension, V : FirRegisteredExtension<P>> registeredExtensions(): ReadOnlyProperty<FirOldExtensionsService, ExtensionsAccessor<P>> {
             val accessor = generateAccessor<V, P>(P::class)
-            return object : ReadOnlyProperty<FirExtensionsService, ExtensionsAccessor<P>> {
-                override fun getValue(thisRef: FirExtensionsService, property: KProperty<*>): ExtensionsAccessor<P> {
+            return object : ReadOnlyProperty<FirOldExtensionsService, ExtensionsAccessor<P>> {
+                override fun getValue(thisRef: FirOldExtensionsService, property: KProperty<*>): ExtensionsAccessor<P> {
                     return ExtensionsAccessor(thisRef.session, accessor.getValue(thisRef, property))
                 }
             }
@@ -93,6 +94,7 @@ class FirExtensionsService(
         )
     }
 
+    @Deprecated("")
     fun registerUserDefinedAnnotation(metaAnnotation: AnnotationFqn, annotations: Collection<FirRegularClass>) {
         for (annotation in annotations) {
             require(annotation.classKind == ClassKind.ANNOTATION_CLASS)
@@ -119,10 +121,12 @@ class FirExtensionsService(
         }
     }
 
+    @Deprecated("")
     val annotations: Set<AnnotationFqn>
         get() = _annotations
     private val _annotations: MutableSet<AnnotationFqn> = mutableSetOf()
 
+    @Deprecated("")
     val metaAnnotations: Set<AnnotationFqn>
         get() = _metaAnnotations
     private val _metaAnnotations: MutableSet<AnnotationFqn> = mutableSetOf()
@@ -130,6 +134,7 @@ class FirExtensionsService(
     private val extensionsWithMetaAnnotations: Multimap<AnnotationFqn, FirExtension> = createMultimap()
 
     // MetaAnnotation -> Annotations
+    @Deprecated("")
     val userDefinedAnnotations: Multimap<AnnotationFqn, AnnotationFqn> = createMultimap()
 
     var registeredExtensionsSize: Int = 0
@@ -170,12 +175,13 @@ class FirExtensionsService(
     }
 }
 
-val FirSession.extensionsService: FirExtensionsService by FirSession.sessionComponentAccessor()
+@Deprecated("")
+val FirSession.oldExtensionsService: FirOldExtensionsService by FirSession.sessionComponentAccessor()
 
 fun FirAnnotationCall.fqName(session: FirSession): FqName? {
     val symbol = session.firSymbolProvider.getSymbolByTypeRef<FirRegularClassSymbol>(annotationTypeRef) ?: return null
     return symbol.classId.asSingleFqName()
 }
 
-val FirExtensionsService.hasExtensions: Boolean
+val FirOldExtensionsService.hasExtensions: Boolean
     get() = registeredExtensionsSize > 0
\ No newline at end of file
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirStatusTransfomerExtension.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirStatusTransfomerExtension.kt
index d8599d9baa0..c728ae85113 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirStatusTransfomerExtension.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirStatusTransfomerExtension.kt
@@ -28,7 +28,7 @@ abstract class FirStatusTransformerExtension(session: FirSession) : FirExtension
     fun interface Factory : FirExtension.Factory<FirStatusTransformerExtension>
 }
 
-val FirExtensionsService.statusTransformerExtensions: FirExtensionsService.ExtensionsAccessor<FirStatusTransformerExtension> by FirExtensionsService.registeredExtensions()
+val FirOldExtensionsService.statusTransformerExtensions: FirOldExtensionsService.ExtensionsAccessor<FirStatusTransformerExtension> by FirOldExtensionsService.registeredExtensions()
 
 inline fun FirDeclarationStatus.transform(
     visibility: Visibility = this.visibility,
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirStatusResolveTransformer.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirStatusResolveTransformer.kt
index 6471bd79101..2116b2627a8 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirStatusResolveTransformer.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirStatusResolveTransformer.kt
@@ -14,7 +14,7 @@ import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.impl.FirDeclarationStatusImpl
 import org.jetbrains.kotlin.fir.expressions.FirBlock
 import org.jetbrains.kotlin.fir.expressions.FirStatement
-import org.jetbrains.kotlin.fir.extensions.extensionsService
+import org.jetbrains.kotlin.fir.extensions.oldExtensionsService
 import org.jetbrains.kotlin.fir.extensions.statusTransformerExtensions
 import org.jetbrains.kotlin.fir.visitors.CompositeTransformResult
 import org.jetbrains.kotlin.fir.visitors.compose
@@ -165,7 +165,7 @@ class FirStatusResolveTransformer(
 
     private fun <D> prepareStatus(declaration: D, status: FirDeclarationStatus): FirDeclarationStatus where D : FirDeclaration, D : FirAnnotationContainer {
         var result = status
-        session.extensionsService.statusTransformerExtensions.forDeclaration(declaration, classes).forEach {
+        session.oldExtensionsService.statusTransformerExtensions.forDeclaration(declaration, classes).forEach {
             result = it.transformStatus(declaration, status)
         }
         return result
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/plugin/FirFirstGenerationTransformer.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/plugin/FirFirstGenerationTransformer.kt
index 6b899211df5..5672594daca 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/plugin/FirFirstGenerationTransformer.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/plugin/FirFirstGenerationTransformer.kt
@@ -12,7 +12,7 @@ import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.expressions.FirStatement
 import org.jetbrains.kotlin.fir.extensions.FirClassGenerationExtension
 import org.jetbrains.kotlin.fir.extensions.classGenerationExtensions
-import org.jetbrains.kotlin.fir.extensions.extensionsService
+import org.jetbrains.kotlin.fir.extensions.oldExtensionsService
 import org.jetbrains.kotlin.fir.extensions.hasExtensions
 import org.jetbrains.kotlin.fir.visitors.CompositeTransformResult
 import org.jetbrains.kotlin.fir.visitors.FirDefaultTransformer
@@ -22,7 +22,7 @@ class FirFirstGenerationTransformer : FirDefaultTransformer<Nothing?>() {
     private lateinit var session: FirSession
     private val generatedDeclarations: MutableList<FirClassGenerationExtension.GeneratedClass> = mutableListOf()
     private lateinit var file: FirFile
-    private val extensionPointService get() = session.extensionsService
+    private val extensionPointService get() = session.oldExtensionsService
 
     override fun transformFile(file: FirFile, data: Nothing?): CompositeTransformResult<FirDeclaration> {
         session = file.session
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/plugin/FirPluginAnnotationsResolveTransformer.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/plugin/FirPluginAnnotationsResolveTransformer.kt
index 2c51e7fafb9..9bfce171db7 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/plugin/FirPluginAnnotationsResolveTransformer.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/plugin/FirPluginAnnotationsResolveTransformer.kt
@@ -33,7 +33,7 @@ class FirPluginAnnotationsResolveTransformer(
     private val annotationTransformer = FirAnnotationResolveTransformer(session, scopeSession)
     private val importTransformer = FirPartialImportResolveTransformer(session)
 
-    private val extensionPointService = session.extensionsService
+    val extensionPointService = session.oldExtensionsService
 
     override fun <E : FirElement> transformElement(element: E, data: Nothing?): CompositeTransformResult<E> {
         throw IllegalStateException("Should not be here")
diff --git a/compiler/tests-common/tests/org/jetbrains/kotlin/fir/AbstractFirBaseDiagnosticsTest.kt b/compiler/tests-common/tests/org/jetbrains/kotlin/fir/AbstractFirBaseDiagnosticsTest.kt
index d669f199fd3..ab217ff1e56 100644
--- a/compiler/tests-common/tests/org/jetbrains/kotlin/fir/AbstractFirBaseDiagnosticsTest.kt
+++ b/compiler/tests-common/tests/org/jetbrains/kotlin/fir/AbstractFirBaseDiagnosticsTest.kt
@@ -26,9 +26,9 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnostic
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirPsiDiagnostic
 import org.jetbrains.kotlin.fir.builder.RawFirBuilder
 import org.jetbrains.kotlin.fir.declarations.FirFile
-import org.jetbrains.kotlin.fir.extensions.FirExtensionsService
+import org.jetbrains.kotlin.fir.extensions.FirOldExtensionsService
 import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
-import org.jetbrains.kotlin.fir.extensions.extensionsService
+import org.jetbrains.kotlin.fir.extensions.oldExtensionsService
 import org.jetbrains.kotlin.fir.extensions.registerExtensions
 import org.jetbrains.kotlin.fir.java.FirJavaModuleBasedSession
 import org.jetbrains.kotlin.fir.java.FirLibrarySession
@@ -80,7 +80,7 @@ abstract class AbstractFirBaseDiagnosticsTest : BaseDiagnosticsTest() {
             builtInsModuleInfo, sessionProvider, allProjectScope, project,
             environment.createPackagePartProvider(allProjectScope)
         ).also {
-            registerFirExtensions(it.extensionsService)
+            registerFirExtensions(it.oldExtensionsService)
         }
 
         val configToSession = modules.mapValues { (config, info) ->
@@ -89,7 +89,7 @@ abstract class AbstractFirBaseDiagnosticsTest : BaseDiagnosticsTest() {
                 project,
                 moduleFiles.mapNotNull { it.ktFile })
             FirJavaModuleBasedSession(info, sessionProvider, scope).also {
-                registerFirExtensions(it.extensionsService)
+                registerFirExtensions(it.oldExtensionsService)
             }
         }
 
@@ -109,7 +109,7 @@ abstract class AbstractFirBaseDiagnosticsTest : BaseDiagnosticsTest() {
         runAnalysis(testDataFile, files, firFilesPerSession)
     }
 
-    open fun registerFirExtensions(service: FirExtensionsService) {
+    open fun registerFirExtensions(service: FirOldExtensionsService) {
         service.registerExtensions(FirExtensionRegistrar.RegisteredExtensions.EMPTY)
     }
 
diff --git a/compiler/tests-common/tests/org/jetbrains/kotlin/fir/SessionTestUtils.kt b/compiler/tests-common/tests/org/jetbrains/kotlin/fir/SessionTestUtils.kt
index 7550945780e..df9157e386c 100644
--- a/compiler/tests-common/tests/org/jetbrains/kotlin/fir/SessionTestUtils.kt
+++ b/compiler/tests-common/tests/org/jetbrains/kotlin/fir/SessionTestUtils.kt
@@ -9,7 +9,7 @@ import com.intellij.openapi.project.Project
 import com.intellij.psi.search.GlobalSearchScope
 import org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment
 import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
-import org.jetbrains.kotlin.fir.extensions.extensionsService
+import org.jetbrains.kotlin.fir.extensions.oldExtensionsService
 import org.jetbrains.kotlin.fir.extensions.registerExtensions
 import org.jetbrains.kotlin.fir.java.FirJavaModuleBasedSession
 import org.jetbrains.kotlin.fir.java.FirLibrarySession
@@ -35,7 +35,7 @@ fun createSession(
     val provider = FirProjectSessionProvider(project)
     return FirJavaModuleBasedSession(moduleInfo, provider, sourceScope).also {
         createSessionForDependencies(project, provider, moduleInfo, librariesScope, packagePartProvider)
-        it.extensionsService.registerExtensions(FirExtensionRegistrar.RegisteredExtensions.EMPTY)
+        it.oldExtensionsService.registerExtensions(FirExtensionRegistrar.RegisteredExtensions.EMPTY)
     }
 }
 
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/fir/FirModuleResolveState.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/fir/FirModuleResolveState.kt
index c2294dd9465..9f9380aa1d0 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/fir/FirModuleResolveState.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/fir/FirModuleResolveState.kt
@@ -15,7 +15,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnostic
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirPsiDiagnostic
 import org.jetbrains.kotlin.fir.declarations.FirFile
 import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
-import org.jetbrains.kotlin.fir.extensions.extensionsService
+import org.jetbrains.kotlin.fir.extensions.oldExtensionsService
 import org.jetbrains.kotlin.fir.extensions.registerExtensions
 import org.jetbrains.kotlin.fir.java.FirProjectSessionProvider
 import org.jetbrains.kotlin.idea.caches.project.ModuleSourceInfo
@@ -40,7 +40,7 @@ interface FirModuleResolveState {
                 sessionProvider.sessionCache[moduleInfo] = moduleBasedSession
             }
             session.also {
-                it.extensionsService.registerExtensions(FirExtensionRegistrar.RegisteredExtensions.EMPTY)
+                it.oldExtensionsService.registerExtensions(FirExtensionRegistrar.RegisteredExtensions.EMPTY)
             }
         }
     }
diff --git a/idea/idea-fir/tests/org/jetbrains/kotlin/idea/fir/AbstractFirMultiModuleResolveTest.kt b/idea/idea-fir/tests/org/jetbrains/kotlin/idea/fir/AbstractFirMultiModuleResolveTest.kt
index b592e8afcac..39171fb3c18 100644
--- a/idea/idea-fir/tests/org/jetbrains/kotlin/idea/fir/AbstractFirMultiModuleResolveTest.kt
+++ b/idea/idea-fir/tests/org/jetbrains/kotlin/idea/fir/AbstractFirMultiModuleResolveTest.kt
@@ -17,7 +17,7 @@ import org.jetbrains.kotlin.fir.declarations.FirFile
 import org.jetbrains.kotlin.fir.declarations.FirResolvePhase
 import org.jetbrains.kotlin.fir.dependenciesWithoutSelf
 import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
-import org.jetbrains.kotlin.fir.extensions.extensionsService
+import org.jetbrains.kotlin.fir.extensions.oldExtensionsService
 import org.jetbrains.kotlin.fir.extensions.registerExtensions
 import org.jetbrains.kotlin.fir.java.FirJavaModuleBasedSession
 import org.jetbrains.kotlin.fir.java.FirLibrarySession
@@ -72,7 +72,7 @@ abstract class AbstractFirMultiModuleResolveTest : AbstractMultiModuleTest() {
     private fun createSession(module: Module, provider: FirProjectSessionProvider): FirJavaModuleBasedSession {
         val moduleInfo = module.productionSourceInfo()!!
         return FirJavaModuleBasedSession(moduleInfo, provider, moduleInfo.contentScope()).also {
-            it.extensionsService.registerExtensions(FirExtensionRegistrar.RegisteredExtensions.EMPTY)
+            it.oldExtensionsService.registerExtensions(FirExtensionRegistrar.RegisteredExtensions.EMPTY)
         }
     }
 
diff --git a/plugins/fir/fir-plugin-prototype/tests/org/jetbrains/kotlin/fir/plugin/AbstractFirAllOpenDiagnosticTest.kt b/plugins/fir/fir-plugin-prototype/tests/org/jetbrains/kotlin/fir/plugin/AbstractFirAllOpenDiagnosticTest.kt
index 5b342a6d7eb..4b730c5d59c 100644
--- a/plugins/fir/fir-plugin-prototype/tests/org/jetbrains/kotlin/fir/plugin/AbstractFirAllOpenDiagnosticTest.kt
+++ b/plugins/fir/fir-plugin-prototype/tests/org/jetbrains/kotlin/fir/plugin/AbstractFirAllOpenDiagnosticTest.kt
@@ -8,12 +8,12 @@ package org.jetbrains.kotlin.fir.plugin
 import org.jetbrains.kotlin.cli.jvm.config.addJvmClasspathRoot
 import org.jetbrains.kotlin.config.CompilerConfiguration
 import org.jetbrains.kotlin.fir.AbstractFirDiagnosticsTest
-import org.jetbrains.kotlin.fir.extensions.FirExtensionsService
+import org.jetbrains.kotlin.fir.extensions.FirOldExtensionsService
 import org.jetbrains.kotlin.fir.extensions.registerExtensions
 import java.io.File
 
 abstract class AbstractFirAllOpenDiagnosticTest : AbstractFirDiagnosticsTest() {
-    override fun registerFirExtensions(service: FirExtensionsService) {
+    override fun registerFirExtensions(service: FirOldExtensionsService) {
         service.registerExtensions(FirAllOpenComponentRegistrar().configure())
     }