FIR2IR: register file first and convert declarations second

This allows to find parent declaration from another file correctly

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrConverter.kt

@@ -35,10 +35,13 @@ object Fir2IrConverter {
         typeTranslator.constantValueGenerator = constantValueGenerator
         val builtIns = IrBuiltIns(moduleDescriptor.builtIns, typeTranslator, signaturer, symbolTable)
         val sourceManager = PsiSourceManager()
-        val fir2irTransformer = Fir2IrVisitor(session, moduleDescriptor, symbolTable, sourceManager, builtIns, fakeOverrideMode)
+        val fir2irVisitor = Fir2IrVisitor(session, moduleDescriptor, symbolTable, sourceManager, builtIns, fakeOverrideMode)
         val irFiles = mutableListOf<IrFile>()
         for (firFile in firFiles) {
-            val irFile = firFile.accept(fir2irTransformer, null) as IrFile
+            fir2irVisitor.registerFile(firFile)
+        }
+        for (firFile in firFiles) {
+            val irFile = firFile.accept(fir2irVisitor, null) as IrFile
             val fileEntry = sourceManager.getOrCreateFileEntry(firFile.psi as KtFile)
             sourceManager.putFileEntry(irFile, fileEntry)
             irFiles += irFile

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt

@@ -80,6 +80,10 @@ class Fir2IrDeclarationStorage(
         fileCache[firFile] = irFile
     }
 
+    fun getIrFile(firFile: FirFile): IrFile {
+        return fileCache[firFile]!!
+    }
+
     fun enterScope(descriptor: DeclarationDescriptor) {
         irSymbolTable.enterScope(descriptor)
         if (descriptor is WrappedSimpleFunctionDescriptor ||
@@ -525,7 +529,7 @@ class Fir2IrDeclarationStorage(
 
     fun getIrFunction(
         function: FirSimpleFunction,
-        irParent: IrDeclarationParent? = null,
+        irParent: IrDeclarationParent?,
         shouldLeaveScope: Boolean = false,
         origin: IrDeclarationOrigin = IrDeclarationOrigin.DEFINED
     ): IrSimpleFunction {

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrVisitor.kt

@@ -87,14 +87,16 @@ class Fir2IrVisitor(
         TODO("Should not be here: ${element.render()}")
     }
 
+    fun registerFile(file: FirFile) {
+        val irFile = IrFileImpl(
+            sourceManager.getOrCreateFileEntry(file.psi as KtFile),
+            moduleDescriptor.getPackage(file.packageFqName).fragments.first()
+        )
+        declarationStorage.registerFile(file, irFile)
+    }
+
     override fun visitFile(file: FirFile, data: Any?): IrFile {
-        return conversionScope.withParent(
-            IrFileImpl(
-                sourceManager.getOrCreateFileEntry(file.psi as KtFile),
-                moduleDescriptor.getPackage(file.packageFqName).fragments.first()
-            )
-        ) {
-            declarationStorage.registerFile(file, this)
+        return conversionScope.withParent(declarationStorage.getIrFile(file)) {
             file.declarations.forEach {
                 val irDeclaration = it.toIrDeclaration() ?: return@forEach
                 declarations += irDeclaration