Null safety

[acoutts]

Will be nice for dartdoc to be migrated soon, assuming all upstream packages are ready.

[jcollins-g]

Blocked on #2500 among other things.

[jcollins-g]

After getting analyzer, mustache is the only non-dev dependency not migrated. However, our dev dependencies on unmigrated code are fairly extensive.

Current status:

$ dart migrate
Migrating /Users/jcollins/dart/dartdoc

See https://dart.dev/go/null-safety-migration for a migration guide.

Note: more than one project found; migrating the top-level project.

Analyzing project...
[-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------\]Bad state: Error: package has unmigrated dependencies.

Before migrating your package, we recommend ensuring that every library it
imports (either directly or indirectly) has been migrated to null safety, so
that you will be able to run your unit tests in sound null checking mode.  You
are currently importing the following non-null-safe libraries:

  package:build/build.dart
  package:build/experiments.dart
  package:build/src/analyzer/resolver.dart
  package:build/src/asset/exceptions.dart
  package:build/src/asset/id.dart
  package:build/src/asset/reader.dart
  package:build/src/asset/writer.dart
  package:build/src/builder/build_step.dart
  package:build/src/builder/build_step_impl.dart
  package:build/src/builder/builder.dart
  package:build/src/builder/exceptions.dart
  package:build/src/builder/file_deleting_builder.dart
  package:build/src/builder/logging.dart
  package:build/src/builder/multiplexing_builder.dart
  package:build/src/builder/post_process_build_step.dart
  package:build/src/builder/post_process_builder.dart
  package:build/src/experiments.dart
  package:build/src/generate/expected_outputs.dart
  package:build/src/generate/run_builder.dart
  package:build/src/generate/run_post_process_builder.dart
  package:build/src/resource/resource.dart
  package:build_resolvers/build_resolvers.dart
  package:build_resolvers/src/analysis_driver.dart
  package:build_resolvers/src/build_asset_uri_resolver.dart
  package:build_resolvers/src/human_readable_duration.dart
  package:build_resolvers/src/resolver.dart
  package:build_test/build_test.dart
  package:build_test/src/assets.dart
  package:build_test/src/builder.dart
  package:build_test/src/fake_watcher.dart
  package:build_test/src/globbing_builder.dart
  package:build_test/src/in_memory_reader.dart
  package:build_test/src/in_memory_writer.dart
  package:build_test/src/matchers.dart
  package:build_test/src/multi_asset_reader.dart
  package:build_test/src/package_reader.dart
  package:build_test/src/record_logs.dart
  package:build_test/src/resolve_source.dart
  package:build_test/src/stub_reader.dart
  package:build_test/src/stub_writer.dart
  package:build_test/src/test_builder.dart
  package:build_test/src/written_asset_reader.dart
  package:dart_style/dart_style.dart
  package:dart_style/src/argument_list_visitor.dart
  package:dart_style/src/call_chain_visitor.dart
  package:dart_style/src/chunk.dart
  package:dart_style/src/chunk_builder.dart
  package:dart_style/src/dart_formatter.dart
  package:dart_style/src/debug.dart
  package:dart_style/src/exceptions.dart
  package:dart_style/src/fast_hash.dart
  package:dart_style/src/line_splitting/line_splitter.dart
  package:dart_style/src/line_splitting/rule_set.dart
  package:dart_style/src/line_splitting/solve_state.dart
  package:dart_style/src/line_splitting/solve_state_queue.dart
  package:dart_style/src/line_writer.dart
  package:dart_style/src/nesting_builder.dart
  package:dart_style/src/nesting_level.dart
  package:dart_style/src/rule/argument.dart
  package:dart_style/src/rule/combinator.dart
  package:dart_style/src/rule/metadata.dart
  package:dart_style/src/rule/rule.dart
  package:dart_style/src/rule/type_argument.dart
  package:dart_style/src/source_code.dart
  package:dart_style/src/source_visitor.dart
  package:dart_style/src/string_compare.dart
  package:dart_style/src/style_fix.dart
  package:dart_style/src/whitespace.dart
  package:graphs/graphs.dart
  package:graphs/src/crawl_async.dart
  package:graphs/src/shortest_path.dart
  package:graphs/src/strongly_connected_components.dart
  package:mustache/mustache.dart
  package:mustache/src/lambda_context.dart
  package:mustache/src/node.dart
  package:mustache/src/parser.dart
  package:mustache/src/renderer.dart
  package:mustache/src/scanner.dart
  package:mustache/src/template.dart
  package:mustache/src/template_exception.dart
  package:mustache/src/token.dart

Please upgrade the packages containing these libraries to null safe versions
before continuing.  To see what null safe package versions are available, run
the following command: `dart pub outdated --mode=null-safety`.

To skip this check and try to migrate anyway, re-run with the flag
`--skip-import-check`.

$ dart pub outdated --mode=null-safety
Showing dependencies that are currently not opted in to null-safety.
[✗] indicates versions without null safety support.
[✓] indicates versions opting in to null safety.

Package Name   Current  Upgradable  Resolvable  Latest   

direct dependencies:
mustache       ✗1.1.1   ✗1.1.1      ✗1.1.1      ✗1.1.1   

dev_dependencies:
build          ✗1.6.3   ✗1.6.3      ✗1.6.3      ✗1.6.3   
build_runner   ✗1.11.3  ✗1.11.3     ✗1.11.3     ✗1.11.3  
build_test     ✗1.3.7   ✗1.3.7      ✗1.3.7      ✗1.3.7   
build_version  ✗2.0.1   ✗2.0.1      ✗2.0.1      ✗2.0.1   
coverage       ✗0.15.2  ✗0.15.2     ✗0.15.2     ✗0.15.2  
dart_style     ✗1.3.13  ✗1.3.13     ✗1.3.13     ✗1.3.13  
You are already using the newest resolvable versions listed in the 'Resolvable' column.
Newer versions, listed in 'Latest', may not be mutually compatible.
$ 

[srawlins]

Oops, done. In January.