[LL FIR] Respect allowKotlinPackage in LLFirKotlinSymbolNamesProvider

- `LLFirProviderHelper` is guarded by `allowKotlinPackage` and the
  symbol names provider should reflect that in the name sets.
- Note that this does not apply to stub-based deserialized symbol
  providers, because they do not pass any value to `allowKotlinPackage`.

^KT-57314

analysis/analysis-internal-utils/src/org/jetbrains/kotlin/analysis/utils/collections/collectionUtils.kt

@@ -9,8 +9,11 @@ package org.jetbrains.kotlin.analysis.utils.collections
  * Maps all elements of this non-empty collection with the given [transform] function to a new mutable set, or returns [emptySet] if this
  * collection is empty.
  *
- * [mapToSet] should be preferred over `collection.mapTo(mutableSetOf()) { ... }` when `collection` may be empty and the resulting set may
- * be cached, because [mapToSet] saves memory by avoiding the creation of an empty mutable set.
+ * [mapToSetOrEmpty] should be preferred over `collection.mapTo(mutableSetOf()) { ... }` when `collection` may be empty and the resulting
+ * set may be cached, because [mapToSetOrEmpty] saves memory by avoiding the creation of an empty mutable set.
  */
-public inline fun <T, R> Collection<T>.mapToSet(transform: (T) -> R): Set<R> =
+public inline fun <T, R> Collection<T>.mapToSetOrEmpty(transform: (T) -> R): Set<R> =
     if (isNotEmpty()) mapTo(mutableSetOf(), transform) else emptySet()
+
+public inline fun <T> Collection<T>.filterToSetOrEmpty(predicate: (T) -> Boolean): Set<T> =
+    filterTo(mutableSetOf(), predicate).ifEmpty { emptySet() }

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/providers/LLFirProviderHelper.kt

@@ -102,7 +102,7 @@ internal class LLFirProviderHelper(
     val symbolNameCache = FirCompositeCachedSymbolNamesProvider.create(
         firSession,
         listOfNotNull(
-            object : LLFirKotlinSymbolNamesProvider(declarationProvider) {
+            object : LLFirKotlinSymbolNamesProvider(declarationProvider, allowKotlinPackage) {
                 // This is a temporary workaround for KTIJ-25536.
                 override fun getPackageNamesWithTopLevelCallables(): Set<String>? = null
             },

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/util/LLFirKotlinSymbolNamesProvider.kt

@@ -6,7 +6,9 @@
 package org.jetbrains.kotlin.analysis.low.level.api.fir.util
 
 import org.jetbrains.kotlin.analysis.providers.KotlinDeclarationProvider
-import org.jetbrains.kotlin.analysis.utils.collections.mapToSet
+import org.jetbrains.kotlin.analysis.utils.collections.filterToSetOrEmpty
+import org.jetbrains.kotlin.analysis.utils.collections.mapToSetOrEmpty
+import org.jetbrains.kotlin.builtins.StandardNames
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolNamesProvider
 import org.jetbrains.kotlin.fir.resolve.providers.FirDelegatingCachedSymbolNamesProvider
@@ -16,23 +18,42 @@ import org.jetbrains.kotlin.name.Name
 
 /**
  * A [FirSymbolNamesProvider] that fetches top-level names from a Kotlin [declarationProvider].
+ *
+ * @param allowKotlinPackage Whether the associated symbol provider is allowed to provide symbols from the `kotlin` package.
  */
 internal open class LLFirKotlinSymbolNamesProvider(
     private val declarationProvider: KotlinDeclarationProvider,
+    private val allowKotlinPackage: Boolean? = null,
 ) : FirSymbolNamesProvider() {
-    override fun getTopLevelClassifierNamesInPackage(packageFqName: FqName): Set<String> =
-        declarationProvider
+    override fun getTopLevelClassifierNamesInPackage(packageFqName: FqName): Set<String> {
+        if (allowKotlinPackage == false && packageFqName.isKotlinPackage()) return emptySet()
+
+        return declarationProvider
             .getTopLevelKotlinClassLikeDeclarationNamesInPackage(packageFqName)
-            .mapToSet { it.asString() }
+            .mapToSetOrEmpty { it.asString() }
+    }
 
-    override fun getPackageNamesWithTopLevelCallables(): Set<String>? =
-        declarationProvider.computePackageSetWithTopLevelCallableDeclarations()
+    override fun getPackageNamesWithTopLevelCallables(): Set<String>? {
+        val packageNames = declarationProvider.computePackageSetWithTopLevelCallableDeclarations()
 
-    override fun getTopLevelCallableNamesInPackage(packageFqName: FqName): Set<Name> =
-        declarationProvider.getTopLevelCallableNamesInPackage(packageFqName).ifEmpty { emptySet() }
+        if (allowKotlinPackage == false && packageNames.any { it.isKotlinPackage() }) {
+            return packageNames.filterToSetOrEmpty { !it.isKotlinPackage() }
+        }
+
+        return packageNames
+    }
+
+    override fun getTopLevelCallableNamesInPackage(packageFqName: FqName): Set<Name> {
+        if (allowKotlinPackage == false && packageFqName.isKotlinPackage()) return emptySet()
+
+        return declarationProvider.getTopLevelCallableNamesInPackage(packageFqName).ifEmpty { emptySet() }
+    }
 
     companion object {
         fun cached(session: FirSession, declarationProvider: KotlinDeclarationProvider): FirCachedSymbolNamesProvider =
             FirDelegatingCachedSymbolNamesProvider(session, LLFirKotlinSymbolNamesProvider(declarationProvider))
     }
 }
+
+private fun FqName.isKotlinPackage(): Boolean = startsWith(StandardNames.BUILT_INS_PACKAGE_NAME)
+private fun String.isKotlinPackage(): Boolean = startsWith(StandardNames.BUILT_INS_PACKAGE_NAME.asString())