[LL FIR] KT-57455 Avoid creating optional annotation class providers

- An `OptionalAnnotationClassesProvider` only needs to be created if the
  package part provider may even have optional annotation classes.
- In the IDE case, the package part provider never provides optional
  annotation classes, so especially in the IDE, we can avoid a lot of
  useless symbol providers with this.

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/project/structure/LLFirLibraryProviderFactory.kt

@@ -35,7 +35,7 @@ internal object LLFirLibraryProviderFactory {
         val packagePartProvider = project.createPackagePartProvider(scope)
         return LLFirModuleWithDependenciesSymbolProvider(
             session,
-            providers = listOf(
+            providers = listOfNotNull(
                 JvmClassFileBasedSymbolProvider(
                     session,
                     moduleDataProvider,
@@ -44,7 +44,7 @@ internal object LLFirLibraryProviderFactory {
                     VirtualFileFinderFactory.getInstance(project).create(scope),
                     LLFirJavaFacadeForBinaries(session, builtinTypes, project.createJavaClassFinder(scope), moduleDataProvider)
                 ),
-                OptionalAnnotationClassesProvider(session, moduleDataProvider, kotlinScopeProvider, packagePartProvider),
+                OptionalAnnotationClassesProvider.createIfNeeded(session, moduleDataProvider, kotlinScopeProvider, packagePartProvider),
             ),
             LLFirDependenciesSymbolProvider(session, listOf(builtinSymbolProvider)),
         )
@@ -60,18 +60,16 @@ internal object LLFirLibraryProviderFactory {
     ): List<FirSymbolProvider> {
         val moduleDataProvider = SingleModuleDataProvider(moduleData)
         val packagePartProvider = project.createPackagePartProvider(scope)
-        return buildList {
-            add(
-                JvmClassFileBasedSymbolProvider(
-                    session,
-                    moduleDataProvider,
-                    kotlinScopeProvider,
-                    packagePartProvider,
-                    VirtualFileFinderFactory.getInstance(project).create(scope),
-                    LLFirJavaFacadeForBinaries(session, builtinTypes, project.createJavaClassFinder(scope), moduleDataProvider)
-                )
-            )
-            add(OptionalAnnotationClassesProvider(session, moduleDataProvider, kotlinScopeProvider, packagePartProvider))
-        }
+        return listOfNotNull(
+            JvmClassFileBasedSymbolProvider(
+                session,
+                moduleDataProvider,
+                kotlinScopeProvider,
+                packagePartProvider,
+                VirtualFileFinderFactory.getInstance(project).create(scope),
+                LLFirJavaFacadeForBinaries(session, builtinTypes, project.createJavaClassFinder(scope), moduleDataProvider)
+            ),
+            OptionalAnnotationClassesProvider.createIfNeeded(session, moduleDataProvider, kotlinScopeProvider, packagePartProvider),
+        )
     }
 }

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/services/PackagePartProviderTestImpl.kt

@@ -37,6 +37,7 @@ internal class PackagePartProviderTestImpl(
                 return providers.flatMapTo(mutableSetOf()) { it.getAllOptionalAnnotationClasses() }.toList()
             }
 
+            override fun mayHaveOptionalAnnotationClasses(): Boolean = providers.any { it.mayHaveOptionalAnnotationClasses() }
         }
     }
 }

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/deserialization/OptionalAnnotationClassesProvider.kt

@@ -84,4 +84,28 @@ class OptionalAnnotationClassesProvider(
 
     override fun getPackage(fqName: FqName): FqName? =
         if (optionalAnnotationClassesAndPackages.second.contains(fqName.asString())) fqName else null
+
+    companion object {
+        /**
+         * Creates a new [OptionalAnnotationClassesProvider] if [packagePartProvider] has any optional annotation classes. Otherwise, the
+         * symbol provider does not need to be created because it would provide no symbols.
+         */
+        fun createIfNeeded(
+            session: FirSession,
+            moduleDataProvider: ModuleDataProvider,
+            kotlinScopeProvider: FirKotlinScopeProvider,
+            packagePartProvider: PackagePartProvider,
+            defaultDeserializationOrigin: FirDeclarationOrigin = FirDeclarationOrigin.Library,
+        ): OptionalAnnotationClassesProvider? {
+            if (!packagePartProvider.mayHaveOptionalAnnotationClasses()) return null
+
+            return OptionalAnnotationClassesProvider(
+                session,
+                moduleDataProvider,
+                kotlinScopeProvider,
+                packagePartProvider,
+                defaultDeserializationOrigin,
+            )
+        }
+    }
 }

compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/incremental/IncrementalPackagePartProvider.kt

@@ -68,4 +68,7 @@ class IncrementalPackagePartProvider(
     override fun getAllOptionalAnnotationClasses(): List<ClassData> =
         moduleMappings.flatMap(JvmPackagePartProviderBase.Companion::getAllOptionalAnnotationClasses) +
                 parent.getAllOptionalAnnotationClasses()
+
+    override fun mayHaveOptionalAnnotationClasses(): Boolean =
+        moduleMappings.any { it.moduleData.optionalAnnotations.isNotEmpty() } || parent.mayHaveOptionalAnnotationClasses()
 }

core/descriptors.jvm/src/org/jetbrains/kotlin/load/kotlin/JvmPackagePartProviderBase.kt

@@ -66,6 +66,11 @@ abstract class JvmPackagePartProviderBase<MappingsKey> : PackageAndMetadataPartP
             getAllOptionalAnnotationClasses(module.mapping)
         }
 
+    override fun mayHaveOptionalAnnotationClasses(): Boolean {
+        // `loadedModules` is mutable, so even a package part provider without optional annotation classes may have some in the future.
+        return true
+    }
+
     companion object {
         fun getAllOptionalAnnotationClasses(module: ModuleMapping): List<ClassData> {
             val data = module.moduleData

core/deserialization.common.jvm/src/org/jetbrains/kotlin/load/kotlin/PackagePartProvider.kt

@@ -28,6 +28,11 @@ interface PackagePartProvider {
 
     fun getAllOptionalAnnotationClasses(): List<ClassData>
 
+    /**
+     * Returns `true` if [getAllOptionalAnnotationClasses] may return a non-empty list.
+     */
+    fun mayHaveOptionalAnnotationClasses(): Boolean
+
     object Empty : PackagePartProvider {
         override fun findPackageParts(packageFqName: String): List<String> = emptyList()
 
@@ -35,6 +40,8 @@ interface PackagePartProvider {
 
         override fun getAllOptionalAnnotationClasses(): List<ClassData> = emptyList()
 
+        override fun mayHaveOptionalAnnotationClasses(): Boolean = false
+
         override fun computePackageSetWithNonClassDeclarations(): Set<String> = emptySet()
     }
 }