[cfe] Move CompilationUnit and SourceCompilationUnitImpl to its own libraries

Change-Id: I09bf4f0199c78cd957b921084f471376b84a2b5c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/438040
Reviewed-by: Chloe Stefantsova <[email protected]>

Author: johnniwinther

pkg/front_end/lib/src/base/export.dart

@@ -5,6 +5,7 @@
 import 'package:kernel/ast.dart';
 
 import '../builder/builder.dart';
+import '../builder/compilation_unit.dart';
 import '../builder/library_builder.dart';
 import 'combinator.dart' show CombinatorBuilder;
 import 'uri_offset.dart';

pkg/front_end/lib/src/base/import.dart

@@ -5,6 +5,7 @@
 import 'package:kernel/ast.dart' show LibraryDependency;
 
 import '../builder/builder.dart';
+import '../builder/compilation_unit.dart';
 import '../builder/library_builder.dart';
 import '../builder/prefix_builder.dart';
 import '../source/source_library_builder.dart';

pkg/front_end/lib/src/base/import_chains.dart

@@ -5,7 +5,7 @@
 import 'package:_fe_analyzer_shared/src/util/link.dart';
 import 'package:_fe_analyzer_shared/src/util/relativize.dart' as uri_extras;
 
-import '../builder/library_builder.dart';
+import '../builder/compilation_unit.dart';
 
 /// Compute the set of distinct import chains to the library at [uri] within
 /// [loadedLibraries].

pkg/front_end/lib/src/base/incremental_compiler.dart

@@ -67,10 +67,11 @@ import '../api_prototype/lowering_predicates.dart'
     show isExtensionThisName, syntheticThisName;
 import '../api_prototype/memory_file_system.dart' show MemoryFileSystem;
 import '../builder/builder.dart' show Builder;
+import '../builder/compilation_unit.dart'
+    show CompilationUnit, SourceCompilationUnit;
 import '../builder/declaration_builders.dart'
     show ClassBuilder, ExtensionBuilder, ExtensionTypeDeclarationBuilder;
-import '../builder/library_builder.dart'
-    show CompilationUnit, LibraryBuilder, SourceCompilationUnit;
+import '../builder/library_builder.dart' show LibraryBuilder;
 import '../builder/member_builder.dart' show MemberBuilder;
 import '../codes/cfe_codes.dart';
 import '../dill/dill_class_builder.dart' show DillClassBuilder;
@@ -81,11 +82,9 @@ import '../kernel/benchmarker.dart' show BenchmarkPhases, Benchmarker;
 import '../kernel/hierarchy/hierarchy_builder.dart' show ClassHierarchyBuilder;
 import '../kernel/internal_ast.dart' show VariableDeclarationImpl;
 import '../kernel/kernel_target.dart' show BuildResult, KernelTarget;
+import '../source/source_compilation_unit.dart' show SourceCompilationUnitImpl;
 import '../source/source_library_builder.dart'
-    show
-        ImplicitLanguageVersion,
-        SourceCompilationUnitImpl,
-        SourceLibraryBuilder;
+    show ImplicitLanguageVersion, SourceLibraryBuilder;
 import '../source/source_loader.dart';
 import '../util/error_reporter_file_copier.dart' show saveAsGzip;
 import '../util/experiment_environment_getter.dart'

pkg/front_end/lib/src/base/loader.dart

@@ -6,6 +6,7 @@ import 'package:_fe_analyzer_shared/src/messages/severity.dart' show Severity;
 import 'package:kernel/ast.dart' show Class, DartType, ExtensionTypeDeclaration;
 
 import '../builder/declaration_builders.dart';
+import '../builder/compilation_unit.dart';
 import '../builder/library_builder.dart';
 import '../builder/type_builder.dart';
 import 'messages.dart' show FormattedMessage, LocatedMessage, Message;

pkg/front_end/lib/src/base/scope.dart

@@ -7,8 +7,8 @@ import 'package:kernel/class_hierarchy.dart';
 import 'package:kernel/type_environment.dart';
 
 import '../builder/builder.dart';
+import '../builder/compilation_unit.dart';
 import '../builder/declaration_builders.dart';
-import '../builder/library_builder.dart';
 import '../builder/metadata_builder.dart';
 import '../builder/prefix_builder.dart';
 import '../kernel/hierarchy/class_member.dart' show ClassMember;

pkg/front_end/lib/src/builder/compilation_unit.dart

@@ -0,0 +1,306 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:_fe_analyzer_shared/src/messages/severity.dart' show Severity;
+import 'package:kernel/ast.dart' show Annotatable, Library, Version;
+import 'package:kernel/reference_from_index.dart';
+
+import '../api_prototype/experimental_flags.dart';
+import '../base/combinator.dart' show CombinatorBuilder;
+import '../base/export.dart' show Export;
+import '../base/loader.dart' show Loader;
+import '../base/messages.dart'
+    show LocatedMessage, Message, ProblemReporting, noLength;
+import '../base/name_space.dart';
+import '../base/scope.dart';
+import '../fragment/fragment.dart';
+import '../kernel/body_builder_context.dart';
+import '../source/name_space_builder.dart';
+import '../source/offset_map.dart';
+import '../source/outline_builder.dart';
+import '../source/source_class_builder.dart';
+import '../source/source_library_builder.dart';
+import '../source/source_loader.dart';
+import 'builder.dart';
+import 'declaration_builders.dart';
+import 'library_builder.dart';
+import 'metadata_builder.dart';
+import 'prefix_builder.dart';
+import 'type_builder.dart';
+
+sealed class CompilationUnit {
+  /// Returns the import uri for the compilation unit.
+  ///
+  /// This is the canonical uri for the compilation unit, for instance
+  /// 'dart:core'.
+  Uri get importUri;
+
+  Uri get fileUri;
+
+  bool get isSynthetic;
+
+  /// If true, the library is not supported through the 'dart.library.*' value
+  /// used in conditional imports and `bool.fromEnvironment` constants.
+  bool get isUnsupported;
+
+  Loader get loader;
+
+  /// The [LibraryBuilder] for the library that this compilation unit belongs
+  /// to.
+  ///
+  /// This is only valid after `SourceLoader.resolveParts` has be called.
+  LibraryBuilder get libraryBuilder;
+
+  bool get isPart;
+
+  bool get isAugmenting;
+
+  LibraryBuilder? get partOfLibrary;
+
+  /// Returns the [Uri]s for the libraries that this library depend upon, either
+  /// through import or export.
+  Iterable<Uri> get dependencies;
+
+  void recordAccess(
+      CompilationUnit accessor, int charOffset, int length, Uri fileUri);
+
+  List<Export> get exporters;
+
+  void addExporter(SourceCompilationUnit exporter,
+      List<CombinatorBuilder>? combinators, int charOffset);
+
+  /// Add a problem with a severity determined by the severity of the message.
+  ///
+  /// If [fileUri] is null, it defaults to `this.fileUri`.
+  ///
+  /// See `Loader.addMessage` for an explanation of the
+  /// arguments passed to this method.
+  void addProblem(Message message, int charOffset, int length, Uri? fileUri,
+      {bool wasHandled = false,
+      List<LocatedMessage>? context,
+      Severity? severity,
+      bool problemOnLibrary = false});
+}
+
+abstract class DillCompilationUnit implements CompilationUnit {}
+
+abstract class SourceCompilationUnit
+    implements CompilationUnit, LibraryFragment {
+  OutlineBuilder createOutlineBuilder();
+
+  /// Creates a [SourceLibraryBuilder] for with this [SourceCompilationUnit] as
+  /// the main compilation unit.
+  SourceLibraryBuilder createLibrary([Library? library]);
+
+  @override
+  SourceLoader get loader;
+
+  OffsetMap get offsetMap;
+
+  /// The language version of this compilation unit as defined by the language
+  /// version of the package it belongs to, if present, or the current language
+  /// version otherwise.
+  ///
+  /// This language version will be used as the language version for the
+  /// compilation unit if the compilation unit does not contain an explicit
+  /// `@dart=` annotation.
+  LanguageVersion get packageLanguageVersion;
+
+  /// Set the language version to an explicit major and minor version.
+  ///
+  /// The default language version specified by the `package_config.json` file
+  /// is passed to the constructor, but the library can have source code that
+  /// specifies another one which should be supported.
+  ///
+  /// Only the first registered language version is used.
+  ///
+  /// [offset] and [length] refers to the offset and length of the source code
+  /// specifying the language version.
+  void registerExplicitLanguageVersion(Version version,
+      {int offset = 0, int length = noLength});
+
+  // TODO(johnniwinther): Remove this.
+  bool get forAugmentationLibrary;
+
+  // TODO(johnniwinther): Remove this.
+  bool get forPatchLibrary;
+
+  /// If this is an compilation unit for an augmentation library, returns the
+  /// import uri for the origin library. Otherwise the [importUri] for the
+  /// compilation unit itself.
+  Uri get originImportUri;
+
+  @override
+  SourceLibraryBuilder get libraryBuilder;
+
+  /// The parent compilation unit.
+  ///
+  /// This is the compilation unit that included this compilation unit as a
+  /// part or `null` if this is the root compilation unit of a library.
+  SourceCompilationUnit? get parentCompilationUnit;
+
+  LibraryFeatures get libraryFeatures;
+
+  /// Returns `true` if the compilation unit is part of a `dart:` library.
+  bool get isDartLibrary;
+
+  LanguageVersion get languageVersion;
+
+  String? get name;
+
+  int finishNativeMethods();
+
+  String? get partOfName;
+
+  Uri? get partOfUri;
+
+  List<MetadataBuilder>? get metadata;
+
+  /// The scope of this compilation unit.
+  ///
+  /// This is the enclosing scope for all declarations within the compilation
+  /// unit.
+  LookupScope get compilationUnitScope;
+
+  /// The prefix scope of this compilation unit.
+  ///
+  /// This contains all imports with prefixes declared in this compilation unit.
+  LookupScope get prefixScope;
+
+  NameSpace get prefixNameSpace;
+
+  bool get mayImplementRestrictedTypes;
+
+  void takeMixinApplications(
+      Map<SourceClassBuilder, TypeBuilder> mixinApplications);
+
+  void addDependencies(Library library, Set<SourceCompilationUnit> seen);
+
+  /// Runs through all part directives in this compilation unit and adds the
+  /// compilation unit for the parts to the [libraryBuilder] by adding them
+  /// to [includedParts]
+  ///
+  /// [usedParts] is used to ensure that a compilation unit is only included in
+  /// one library. If the compilation unit is part of two libraries, it is only
+  /// included in the first and reported as an error on the second.
+  ///
+  /// This should only be called on the main compilation unit for
+  /// [libraryBuilder]. Inclusion of nested parts is from within this method,
+  /// using [becomePart] for each individual subpart.
+  void includeParts(
+      List<SourceCompilationUnit> includedParts, Set<Uri> usedParts);
+
+  /// Includes this compilation unit as a part of [libraryBuilder] with
+  /// [parentCompilationUnit] as the parent compilation unit.
+  ///
+  /// The parent compilation unit is used to define the compilation unit
+  /// scope of this compilation unit.
+  ///
+  /// All fragment in this compilation unit will be added to
+  /// [libraryNameSpaceBuilder].
+  ///
+  /// If parts with parts is supported (through the enhanced parts feature),
+  /// the compilation units of the part directives in this compilation unit
+  /// will be added [libraryBuilder] recursively.
+  void becomePart(
+      SourceLibraryBuilder libraryBuilder,
+      LibraryNameSpaceBuilder libraryNameSpaceBuilder,
+      SourceCompilationUnit parentCompilationUnit,
+      List<SourceCompilationUnit> includedParts,
+      Set<Uri> usedParts,
+      {required bool allowPartInParts});
+
+  void buildOutlineExpressions(
+      {required Annotatable annotatable,
+      required Uri annotatableFileUri,
+      required BodyBuilderContext bodyBuilderContext});
+
+  /// Reports that [feature] is not enabled, using [charOffset] and
+  /// [length] for the location of the message.
+  ///
+  /// Return the primary message.
+  Message reportFeatureNotEnabled(
+      LibraryFeature feature, Uri fileUri, int charOffset, int length);
+
+  /// Registers that [augmentation] is a part of the library for which this is
+  /// the main compilation unit.
+  void registerAugmentation(CompilationUnit augmentation);
+
+  /// Reports [message] on all compilation units that access this compilation
+  /// unit.
+  void addProblemAtAccessors(Message message);
+
+  Iterable<LibraryAccess> get accessors;
+
+  /// Non-null if this library causes an error upon access, that is, there was
+  /// an error reading its source.
+  abstract Message? accessProblem;
+
+  /// Add a problem that might not be reported immediately.
+  ///
+  /// Problems will be issued after source information has been added.
+  /// Once the problems has been issued, adding a new "postponed" problem will
+  /// be issued immediately.
+  void addPostponedProblem(
+      Message message, int charOffset, int length, Uri fileUri);
+
+  void issuePostponedProblems();
+
+  void markLanguageVersionFinal();
+
+  /// Index of the library we use references for.
+  IndexedLibrary? get indexedLibrary;
+
+  void addSyntheticImport(
+      {required Uri importUri,
+      required String? prefix,
+      required List<CombinatorBuilder>? combinators,
+      required bool deferred});
+
+  void addImportedBuilderToScope(
+      {required String name,
+      required NamedBuilder builder,
+      required int charOffset});
+
+  void addImportsToScope();
+
+  void buildOutlineNode(Library library);
+
+  int finishDeferredLoadTearOffs(Library library);
+
+  /// This method instantiates type parameters to their bounds in some cases
+  /// where they were omitted by the programmer and not provided by the type
+  /// inference.  The method returns the number of distinct type parameters
+  /// that were instantiated in this library.
+  int computeDefaultTypes(TypeBuilder dynamicType, TypeBuilder nullType,
+      TypeBuilder bottomType, ClassBuilder objectClass);
+
+  /// Computes variances of type parameters on typedefs.
+  ///
+  /// The variance property of type parameters on typedefs is computed from the
+  /// use of the parameters in the right-hand side of the typedef definition.
+  int computeVariances();
+
+  /// Adds all unbound nominal parameters to [nominalParameters] and unbound
+  /// structural parameters to [structuralParameters], mapping them to
+  /// [libraryBuilder].
+  ///
+  /// This is used to compute the bounds of type parameters while taking the
+  /// bound dependencies, which might span multiple libraries, into account.
+  void collectUnboundTypeParameters(
+      SourceLibraryBuilder libraryBuilder,
+      Map<NominalParameterBuilder, SourceLibraryBuilder> nominalParameters,
+      Map<StructuralParameterBuilder, SourceLibraryBuilder>
+          structuralParameters);
+
+  /// Adds [prefixFragment] to library name space.
+  ///
+  /// Returns `true` if the prefix name was new to the name space. Otherwise the
+  /// prefix was merged with an existing prefix of the same name.
+  // TODO(johnniwinther): Remove this.
+  bool addPrefixFragment(
+      String name, PrefixFragment prefixFragment, int charOffset);
+
+  int resolveTypes(ProblemReporting problemReporting);
+}