Flutter and Angular Dart should adopt optional new and const

[JekCharlsonYu]

• AngularDart examples: angulardart/angular@072a5d6

• Flutter: Meta-issue: Update all code to use optional new/const flutter/flutter#18604

[mit-mit]

From discussion with @Hixie, the preferred approach is to have a lint for this (opened #32602 to track)

[Hixie]

A lint would be great! cc @a14n who likes lints. :-)

[matanlurey]

We'd prefer to have a single collection of lints that best represents the style guide, and not to have to enable individual lints. As such we are not conforming to this new optional new/const until that is a possibility (and is vetted by the style guide team for both correctness and performance - we've had lints that literally caused IDE crashes due to leaks/memory usage).

[mit-mit]

We are asking for a lint that individual teams / repos / apps / package can opt-in to enforcing at their own schedule.

[Hixie]

FWIW, Flutter has a pair of "recommended" analysis options files, one for people who want an easy-go-lucky style (the default for flutter analyze), and one for people who want a super-strict style (the default for the Flutter repository itself). I could totally see the Effective Dart style guide having a recommended set of lints in the same way.

[dgrove]

@JekCharlsonYu this looks unlikely to happen by Beta 4.

@a14n are you taking on the lint?

[a14n]

@dgrove there's a pending PR for that dart-archive/linter#936. But as the rules have evolved it needs perhaps some changes. On vacation I will not work on it before a week.

[JekCharlsonYu]

@dgrove moving it to Dart2 Stable at least.