[FIR] Get rid of FirSymbolProvider.getClassNamesInPackage

There was one non-removable usage of those function in FirJavaElementFinder
  and three non-trivial implementation
- `FirProvider.SymbolProvider`
- `KotlinDeserializedJvmSymbolsProvider`
- `FirBuiltinSymbolProvider`

First implementation was moved to `FirProvider` and other two was
  deleted, because in FirJavaElementFinder we need lookup only in
  classes from source code, so such methods in library providers are
  useless

#KT-41048

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/FirJavaElementFinder.kt

@@ -43,13 +43,12 @@ class FirJavaElementFinder(
     private val firProvider = session.firProvider
 
     override fun findPackage(qualifiedName: String): PsiPackage? {
-        if (firProvider.symbolProvider.getClassNamesInPackage(FqName(qualifiedName)).isEmpty()) return null
+        if (firProvider.symbolProvider.getPackage(FqName(qualifiedName)) == null) return null
         return PsiPackageImpl(psiManager, qualifiedName)
     }
 
     override fun getClasses(psiPackage: PsiPackage, scope: GlobalSearchScope): Array<PsiClass> {
-        return firProvider.symbolProvider
+        return firProvider.getClassNamesInPackage(FqName(psiPackage.qualifiedName))
-            .getClassNamesInPackage(FqName(psiPackage.qualifiedName))
             .mapNotNull { findClass(psiPackage.qualifiedName + "." + it.identifier, scope) }
             .toTypedArray()
     }

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

@@ -408,11 +408,6 @@ class KotlinDeserializedJvmSymbolsProvider(
         }
     }
 
-    override fun getClassNamesInPackage(fqName: FqName): Set<Name> =
-        javaClassFinder.findPackage(fqName)
-            ?.getClasses { true }.orEmpty()
-            .mapTo(sortedSetOf(), JavaClass::name)
-
     private fun findRegularClass(classId: ClassId): FirRegularClass? =
         getClassLikeSymbolByFqName(classId)?.fir as? FirRegularClass
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/FirProvider.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirClassLikeSymbol
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
 
 @RequiresOptIn
 annotation class FirProviderInternals
@@ -44,4 +45,6 @@ abstract class FirProvider : FirSessionComponent {
 
     @FirProviderInternals
     abstract fun recordGeneratedMember(owner: FirAnnotatedDeclaration, klass: FirDeclaration)
+
+    abstract fun getClassNamesInPackage(fqName: FqName): Set<Name>
 }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/FirSymbolProvider.kt

@@ -56,9 +56,6 @@ abstract class FirSymbolProvider : FirSessionComponent {
 
     abstract fun getNestedClassifierScope(classId: ClassId): FirScope?
 
-    @Deprecated("will be deleted soon")
-    open fun getClassNamesInPackage(fqName: FqName): Set<Name> = emptySet()
-
     abstract fun getPackage(fqName: FqName): FqName? // TODO: Replace to symbol sometime
 }
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirBuiltinSymbolProvider.kt

@@ -257,12 +257,6 @@ class FirBuiltinSymbolProvider(val session: FirSession, val kotlinScopeProvider:
         }
     }
 
-    override fun getClassNamesInPackage(fqName: FqName): Set<Name> {
-        return allPackageFragments[fqName]?.flatMapTo(mutableSetOf()) {
-            it.getAllClassNames()
-        } ?: emptySet()
-    }
-
     private fun findRegularClass(classId: ClassId): FirRegularClass? =
         getClassLikeSymbolByFqName(classId)?.fir
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirCompositeSymbolProvider.kt

@@ -36,8 +36,4 @@ class FirCompositeSymbolProvider(val providers: List<FirSymbolProvider>) : FirSy
     override fun getClassLikeSymbolByFqName(classId: ClassId): FirClassLikeSymbol<*>? {
         return providers.firstNotNullResult { it.getClassLikeSymbolByFqName(classId) }
     }
-
-    override fun getClassNamesInPackage(fqName: FqName): Set<Name> {
-        return providers.flatMapTo(mutableSetOf()) { it.getClassNamesInPackage(fqName) }
-    }
 }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirDependenciesSymbolProviderImpl.kt

@@ -7,8 +7,8 @@ package org.jetbrains.kotlin.fir.resolve.providers.impl
 
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.dependenciesWithoutSelf
-import org.jetbrains.kotlin.fir.resolve.providers.AbstractFirSymbolProvider
 import org.jetbrains.kotlin.fir.resolve.firSymbolProvider
+import org.jetbrains.kotlin.fir.resolve.providers.AbstractFirSymbolProvider
 import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProviderInternals
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.symbols.CallableId
@@ -63,8 +63,4 @@ open class FirDependenciesSymbolProviderImpl(val session: FirSession) : Abstract
             null
         }
     }
-
-    override fun getClassNamesInPackage(fqName: FqName): Set<Name> {
-        return dependencyProviders.flatMapTo(mutableSetOf()) { it.getClassNamesInPackage(fqName) }
-    }
 }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirProviderImpl.kt

@@ -18,7 +18,9 @@ import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.scopes.KotlinScopeProvider
 import org.jetbrains.kotlin.fir.scopes.impl.nestedClassifierScope
 import org.jetbrains.kotlin.fir.symbols.CallableId
-import org.jetbrains.kotlin.fir.symbols.impl.*
+import org.jetbrains.kotlin.fir.symbols.impl.FirAccessorSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirClassLikeSymbol
 import org.jetbrains.kotlin.fir.visitors.FirDefaultVisitor
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
@@ -76,10 +78,6 @@ class FirProviderImpl(val session: FirSession, val kotlinScopeProvider: KotlinSc
             if (getFirFilesByPackage(fqName).isNotEmpty()) return fqName
             return null
         }
-
-        override fun getClassNamesInPackage(fqName: FqName): Set<Name> {
-            return state.classesInPackage[fqName] ?: emptySet()
-        }
     }
 
     @FirProviderInternals
@@ -259,6 +257,10 @@ class FirProviderImpl(val session: FirSession, val kotlinScopeProvider: KotlinSc
             state.setFrom(newState)
         }
     }
+
+    override fun getClassNamesInPackage(fqName: FqName): Set<Name> {
+        return state.classesInPackage[fqName] ?: emptySet()
+    }
 }
 
 private const val rebuildIndex = true

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/providers/FirIdeProvider.kt

@@ -112,6 +112,11 @@ internal class FirIdeProvider(
         TODO()
     }
 
+    override fun getClassNamesInPackage(fqName: FqName): Set<Name> {
+        // TODO: KT-41048
+        return emptySet()
+    }
+
     private inner class SymbolProvider : FirSymbolProvider() {
         override fun getTopLevelCallableSymbols(packageFqName: FqName, name: Name): List<FirCallableSymbol<*>> =
             providerHelper.getTopLevelCallableSymbols(packageFqName, name)

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/scopes/KtFirPackageScope.kt

@@ -5,7 +5,6 @@
 
 package org.jetbrains.kotlin.idea.frontend.api.fir.scopes
 
-import org.jetbrains.kotlin.fir.resolve.firSymbolProvider
 import org.jetbrains.kotlin.fir.scopes.impl.FirPackageMemberScope
 import org.jetbrains.kotlin.idea.frontend.api.ValidityToken
 import org.jetbrains.kotlin.idea.frontend.api.ValidityTokenOwner
@@ -25,7 +24,6 @@ internal class KtFirPackageScope(
 ) : KtPackageScope, ValidityTokenOwner {
     private val firScope by weakRef(firScope)
     override val fqName: FqName get() = firScope.fqName
-    private val provider get() = firScope.session.firSymbolProvider
 
     override fun getCallableNames(): Set<Name> = withValidityAssertion {
         // TODO: KT-41048
@@ -33,7 +31,8 @@ internal class KtFirPackageScope(
     }
 
     override fun getClassLikeSymbolNames(): Set<Name> = withValidityAssertion {
-        provider.getClassNamesInPackage(fqName)
+        // TODO: KT-41048
+        emptySet()
     }
 
     override fun getCallableSymbols(): Sequence<KtCallableSymbol> = withValidityAssertion {