Elements. Create loadLibrary() function with reference, lazily.

Related to https://dart-review.googlesource.com/c/sdk/+/393164

Change-Id: Ia448ff42c9de538be9a8f6f2101dff0c949671d3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/393260
Commit-Queue: Konstantin Shcheglov <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Phil Quitslund <[email protected]>

Author: scheglov

pkg/analyzer/lib/src/dart/analysis/driver.dart

@@ -98,7 +98,7 @@ import 'package:meta/meta.dart';
 // TODO(scheglov): Clean up the list of implicitly analyzed files.
 class AnalysisDriver {
   /// The version of data format, should be incremented on every format change.
-  static const int DATA_VERSION = 412;
+  static const int DATA_VERSION = 413;
 
   /// The number of exception contexts allowed to write. Once this field is
   /// zero, we stop writing any new exception contexts in this process.

pkg/analyzer/lib/src/dart/element/element.dart

@@ -6328,10 +6328,9 @@ class LibraryElementImpl extends ElementImpl
   /// an entry point.
   FunctionElement? _entryPoint;
 
-  /// The element representing the synthetic function `loadLibrary` that is
-  /// defined for this library, or `null` if the element has not yet been
-  /// created.
-  late FunctionElement _loadLibraryFunction;
+  /// The provider for the synthetic function `loadLibrary` that is defined
+  /// for this library.
+  late final LoadLibraryFunctionProvider loadLibraryProvider;
 
   @override
   int nameLength;
@@ -6605,13 +6604,14 @@ class LibraryElementImpl extends ElementImpl
   }
 
   @override
-  FunctionElement get loadLibraryFunction {
-    return _loadLibraryFunction;
+  FunctionElementImpl get loadLibraryFunction {
+    return loadLibraryFunction2.firstFragment;
   }
 
   @override
-  TopLevelFunctionElement get loadLibraryFunction2 =>
-      loadLibraryFunction as TopLevelFunctionElement;
+  TopLevelFunctionElementImpl get loadLibraryFunction2 {
+    return loadLibraryProvider.getElement(this);
+  }
 
   @override
   List<ElementAnnotationImpl> get metadata {
@@ -6732,18 +6732,6 @@ class LibraryElementImpl extends ElementImpl
     builder.writeLibraryElement(this);
   }
 
-  /// Create the [FunctionElement] to be returned by [loadLibraryFunction].
-  /// The [typeProvider] must be already set.
-  void createLoadLibraryFunction() {
-    var fragment = FunctionElementImpl(FunctionElement.LOAD_LIBRARY_NAME, -1)
-      ..enclosingElement3 = library
-      ..isSynthetic = true
-      ..returnType = typeProvider.futureDynamicType;
-    _loadLibraryFunction = fragment;
-    // TODO(scheglov): create it sooner, with actual reference.
-    TopLevelFunctionElementImpl(Reference.root(), fragment);
-  }
-
   @override
   ClassElement? getClass(String name) {
     for (var unitElement in units) {
@@ -6959,6 +6947,38 @@ class LibraryImportElementImpl extends _ExistingElementImpl
   }
 }
 
+/// The provider for the lazily created `loadLibrary` function.
+final class LoadLibraryFunctionProvider {
+  final Reference fragmentReference;
+  final Reference elementReference;
+  TopLevelFunctionElementImpl? _element;
+
+  LoadLibraryFunctionProvider({
+    required this.fragmentReference,
+    required this.elementReference,
+  });
+
+  TopLevelFunctionElementImpl getElement(LibraryElementImpl library) {
+    return _element ??= _create(library);
+  }
+
+  TopLevelFunctionElementImpl _create(LibraryElementImpl library) {
+    var name = FunctionElement.LOAD_LIBRARY_NAME;
+
+    var fragment = FunctionElementImpl(name, -1);
+    fragment.name2 = name;
+    fragment.isSynthetic = true;
+    fragment.isStatic = true;
+    fragment.returnType = library.typeProvider.futureDynamicType;
+    fragment.enclosingElement3 = library.definingCompilationUnit;
+
+    fragment.reference = fragmentReference;
+    fragmentReference.element = fragment;
+
+    return TopLevelFunctionElementImpl(elementReference, fragment);
+  }
+}
+
 class LocalFunctionElementImpl extends ExecutableElementImpl2
     with WrappedElementMixin
     implements LocalFunctionElement {

pkg/analyzer/lib/src/summary2/bundle_reader.dart

@@ -661,6 +661,11 @@ class LibraryReader {
       _reader.readUInt30List(),
     );
 
+    libraryElement.loadLibraryProvider = LoadLibraryFunctionProvider(
+      fragmentReference: _readReference(),
+      elementReference: _readReference(),
+    );
+
     // Read the library units.
     libraryElement.definingCompilationUnit = _readUnitElement(
       libraryElement: libraryElement,
@@ -1182,7 +1187,6 @@ class LibraryReader {
         TopLevelFunctionElementImpl(reference2, fragment);
       }
 
-
       var linkedData = FunctionElementLinkedData(
         reference: reference,
         libraryReader: this,

pkg/analyzer/lib/src/summary2/bundle_writer.dart

@@ -104,6 +104,7 @@ class BundleWriter {
     _writeLanguageVersion(libraryElement.languageVersion);
     _writeExportedReferences(libraryElement.exportedReferences);
     _sink.writeUint30List(libraryElement.nameUnion.mask);
+    _writeLoadLibraryFunctionReferences(libraryElement);
 
     // Write the library units.
     // This will write also resolution data, e.g. for classes.
@@ -483,6 +484,12 @@ class BundleWriter {
     }
   }
 
+  void _writeLoadLibraryFunctionReferences(LibraryElementImpl library) {
+    var element = library.loadLibraryFunction2;
+    _writeReference2(element.firstFragment.reference);
+    _writeReference2(element.reference);
+  }
+
   void _writeMethodElement(MethodElementImpl element) {
     _sink.writeUInt30(_resolutionSink.offset);
     _writeReference(element);

pkg/analyzer/lib/src/summary2/library_builder.dart

@@ -1258,6 +1258,25 @@ class LibraryBuilder with MacroApplicationsContainer {
     );
   }
 
+  /// We want to have stable references for `loadLibrary` function. But we
+  /// cannot create the function itself right now, because the type provider
+  /// might be not available yet. So, we create references together with the
+  /// library, and create the fragment and element later.
+  void _createLoadLibraryReferences() {
+    var name = FunctionElement.LOAD_LIBRARY_NAME;
+
+    var fragmentContainer = units[0].reference.getChild('@function');
+    var fragmentReference = fragmentContainer.addChild(name);
+
+    var elementContainer = reference.getChild('@function');
+    var elementReference = elementContainer.addChild(name);
+
+    element.loadLibraryProvider = LoadLibraryFunctionProvider(
+      fragmentReference: fragmentReference,
+      elementReference: elementReference,
+    );
+  }
+
   /// These elements are implicitly declared in `dart:core`.
   void _declareDartCoreDynamicNever() {
     if (reference.name == 'dart:core') {
@@ -1316,7 +1335,6 @@ class LibraryBuilder with MacroApplicationsContainer {
     libraryElement.isSynthetic = !libraryFile.exists;
     libraryElement.languageVersion = libraryUnitNode.languageVersion;
     _bindReference(libraryReference, libraryElement);
-    elementFactory.setLibraryTypeSystem(libraryElement);
 
     var unitContainerRef = libraryReference.getChild('@fragment');
 
@@ -1354,6 +1372,9 @@ class LibraryBuilder with MacroApplicationsContainer {
       units: linkingUnits,
     );
 
+    builder._createLoadLibraryReferences();
+    elementFactory.setLibraryTypeSystem(libraryElement);
+
     if (inputMacroResult != null) {
       var import = inputLibrary.addMacroPart(
         inputMacroResult.code,

pkg/analyzer/lib/src/summary2/linked_element_factory.dart

@@ -310,8 +310,6 @@ class LinkedElementFactory {
     libraryElement.typeProvider = analysisContext.typeProvider;
     libraryElement.typeSystem = analysisContext.typeSystem;
     libraryElement.hasTypeProviderSystemSet = true;
-
-    libraryElement.createLoadLibraryFunction();
   }
 
   void _disposeLibrary(Element? libraryElement) {

pkg/analyzer/test/src/dart/resolution/function_reference_test.dart

@@ -2804,11 +2804,11 @@ ExpressionStatement
     period: .
     identifier: SimpleIdentifier
       token: loadLibrary
-      staticElement: loadLibrary@-1
-      element: <exception>
+      staticElement: package:test/a.dart::<fragment>::@function::loadLibrary
+      element: package:test/a.dart::@function::loadLibrary
       staticType: Future<dynamic> Function()
-    staticElement: loadLibrary@-1
-    element: <exception>
+    staticElement: package:test/a.dart::<fragment>::@function::loadLibrary
+    element: package:test/a.dart::@function::loadLibrary
     staticType: Future<dynamic> Function()
   semicolon: ;
 ''');

pkg/analyzer/test/src/dart/resolution/method_invocation_test.dart

@@ -2286,8 +2286,8 @@ MethodInvocation
   operator: ?.
   methodName: SimpleIdentifier
     token: loadLibrary
-    staticElement: loadLibrary@-1
-    element: <exception>
+    staticElement: dart:math::<fragment>::@function::loadLibrary
+    element: dart:math::@function::loadLibrary
     staticType: Future<dynamic> Function()
   argumentList: ArgumentList
     leftParenthesis: (
@@ -3554,8 +3554,8 @@ MethodInvocation
   operator: .
   methodName: SimpleIdentifier
     token: loadLibrary
-    staticElement: loadLibrary@-1
-    element: <exception>
+    staticElement: dart:math::<fragment>::@function::loadLibrary
+    element: dart:math::@function::loadLibrary
     staticType: Future<dynamic> Function()
   argumentList: ArgumentList
     leftParenthesis: (
@@ -3588,8 +3588,8 @@ MethodInvocation
   operator: .
   methodName: SimpleIdentifier
     token: loadLibrary
-    staticElement: loadLibrary@-1
-    element: <exception>
+    staticElement: dart:math::<fragment>::@function::loadLibrary
+    element: dart:math::@function::loadLibrary
     staticType: Future<dynamic> Function()
   argumentList: ArgumentList
     leftParenthesis: (