Dart 3 tools changes

[mit-mit]

This is a meta-issue to discuss, triage, and track tools changes in the Dart 3 release. A core theme of this release is getting rid of historical bagage, so we should look at cleaning up historical tooling artefacts.

Included in Dart 3

• Deprecate historical CLI tools, and combine everything into the dart tool:
  [breaking change]: Deprecation and discontinuation of standalone Dart tools #46100
• Remove support for .packages, now replaced with .dart_tool/package_config.json:
  [breaking change] discontinue .packages file #48272
• Hide dart format --fix (now dart fix):
  Remove --fix dart_style#1153
• Cleanup web dev compiler files shipped in the SDK:
  Cleanup DDC files copied to the released SDK for Dart 3.0 #50700
• Remove lints from the linter no longer relevant:
  • remove deprecated lints in 3.0 #58948
  • proposal: remove lints deprecated for 3.0 core#789
• Remove Dart null safety migration tools, and require using Dart 2.19 for migrations:
  Do we need to ship the null safety migration tool in Dart 3.0? #50319,
  Remove features for migrating to null safety pub#3713
  • dart migrate
  • dart pub upgrade --null-safety
  • dart pub outdated --mode=null-safety
• Remove deprecated "strong mode" analyzer mode:
  Remove analyzer's deprecated analysis modes: no-implicit-casts and no-implicit-dynamic #50679
• Cleanup of various dart CLI tool commands:
  [Meta] Dart 3.0 CLI Cleanup #50973
• Disable Observatory by-default (should use DevTools):
  edead9c
• JS compiler flags:
  JavaScript compilers support for --null-assertions in Dart 3.0 #50711
• Implicit get command:
  dart cli commands should run pub get #50422

Postponed

- [ ] Standardized location for user-level SDK files. Currently these are scattered across ~/.pub-cache, .dartServer, .dart, .flutter, .flutter-devtools, etc.
- [ ] Some dart subcommand for managing this location (viewing size, pruning it, etc.)
- [ ] Consider using OS-standard locations for these (e.g. on Windows)

[vsmenon]

@mit-mit - anything we need to land here for the beta? We still have one item unchecked.

[vsmenon]

@pq - only open item here is dart-lang/core#789. I assume we don't need that for the beta cut. Is this something we want for Dart 3 stable?

[pq]

@vsmenon: correct. We only want that for stable.

[mit-mit]

Yeah, we're good here for beta!

[vsmenon]

Anything we need for stable?

[mit-mit]

Last issue is dart-lang/core#789. I'll ping on that.

[mit-mit]

All done 🥳