Convert options/logging libraries to null safety (#2748)

* Update analyzer version to 2.0.0

* grind build for analyzer 2

* First steps toward migrating

* Start migrating some things around the edges and see what happens

* Basic migration infrastruture for new NNBD branch

* use separate workflow file for nnbd branch, for clarity

* thinko

* Switch to using CompilationUnitElement.classes (#2743)

* Ignore null safe import warnings for presubmits

* Prepare dartdoc_options for migration (#2745)

* more specific imports in options

* do not allow autoinitialization

* dartfmt

* parameterize the valueWithContext type

* Use alternative constructors instead of externalizing, didn't realize the autodetect was so widely used

* more subclasses

* Empty commit to straighten out GitHub Actions

* dartfmt

Author: jcollins-g

analysis_options_presubmit.yaml

@@ -10,6 +10,8 @@ analyzer:
     ### Extra ignores for presubmit
     deprecated_member_use: ignore
     deprecated_member_use_from_same_package: ignore
+    ### Temporary presubmit ignore for NNBD migration
+    import_of_legacy_library_into_null_safe: ignore
   exclude:
     - 'doc/**'
     - 'lib/src/third_party/pkg/**'

lib/options.dart

@@ -1,5 +1,3 @@
-// @dart=2.9
-
 import 'dart:io' show stderr, exitCode;
 
 import 'package:analyzer/file_system/file_system.dart';
@@ -12,34 +10,24 @@ import 'package:dartdoc/src/package_meta.dart';
 
 /// Helper class that consolidates option contexts for instantiating generators.
 class DartdocGeneratorOptionContext extends DartdocOptionContext {
-  DartdocGeneratorOptionContext(
-      DartdocOptionSet optionSet, Folder dir, ResourceProvider resourceProvider)
+  DartdocGeneratorOptionContext(DartdocOptionSet optionSet, Folder? dir,
+      ResourceProvider resourceProvider)
       : super(optionSet, dir, resourceProvider);
-
   DartdocGeneratorOptionContext.fromDefaultContextLocation(
       DartdocOptionSet optionSet, ResourceProvider resourceProvider)
       : super.fromDefaultContextLocation(optionSet, resourceProvider);
 
-  // TODO(migration): Make late final with initializer when Null Safe.
-  String _header;
-
   /// Returns the joined contents of any 'header' files specified in options.
-  String get header =>
-      _header ??= _joinCustomTextFiles(optionSet['header'].valueAt(context));
-
-  // TODO(migration): Make late final with initializer when Null Safe.
-  String _footer;
+  late final String header =
+      _joinCustomTextFiles(optionSet['header'].valueAt(context));
 
   /// Returns the joined contents of any 'footer' files specified in options.
-  String get footer =>
-      _footer ??= _joinCustomTextFiles(optionSet['footer'].valueAt(context));
-
-  // TODO(migration): Make late final with initializer when Null Safe.
-  String _footerText;
+  late final String footer =
+      _joinCustomTextFiles(optionSet['footer'].valueAt(context));
 
   /// Returns the joined contents of any 'footer-text' files specified in
   /// options.
-  String get footerText => _footerText ??=
+  late final String footerText =
       _joinCustomTextFiles(optionSet['footerText'].valueAt(context));
 
   String _joinCustomTextFiles(Iterable<String> paths) => paths
@@ -63,8 +51,8 @@ class DartdocGeneratorOptionContext extends DartdocOptionContext {
 
 class DartdocProgramOptionContext extends DartdocGeneratorOptionContext
     with LoggingContext {
-  DartdocProgramOptionContext(
-      DartdocOptionSet optionSet, Folder dir, ResourceProvider resourceProvider)
+  DartdocProgramOptionContext(DartdocOptionSet optionSet, Folder? dir,
+      ResourceProvider resourceProvider)
       : super(optionSet, dir, resourceProvider);
   DartdocProgramOptionContext.fromDefaultContextLocation(
       DartdocOptionSet optionSet, ResourceProvider resourceProvider)
@@ -91,10 +79,10 @@ Future<List<DartdocOption<bool>>> createDartdocProgramOptions(
   ];
 }
 
-Future<DartdocProgramOptionContext> parseOptions(
+Future<DartdocProgramOptionContext?> parseOptions(
   PackageMetaProvider packageMetaProvider,
   List<String> arguments, {
-  OptionGenerator additionalOptions,
+  OptionGenerator? additionalOptions,
 }) async {
   var optionSet = await DartdocOptionSet.fromOptionGenerators(
       'dartdoc',

lib/src/logging.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// @dart=2.9
-
 import 'dart:convert';
 import 'dart:io' show stderr, stdout;
 

pubspec.yaml

@@ -10,7 +10,7 @@ dependencies:
   analyzer: ^2.0.0
   args: ^2.0.0
   charcode: ^1.2.0
-  collection: ^1.15.0-nullsafety.4
+  collection: ^1.15.0
   cli_util: ^0.3.0
   crypto: ^3.0.0
   glob: ^2.0.0