Lasse R.H. Nielsen
4d750a862d
We introduced a `nullFuture` during the null-safety migration where
we changed some methods to no longer allow returning `null`,
and they therefore had to return a `Future`.
That affected timing, because returning `null` was processed
synchronously, and that change in timing made some tests fail.
Rather that fix the fragile tests, we made the function return
a recognizable future, a canonical `Future<Null>.value(null)`,
and then recognized it and took a synchronous path for it.
That caused other issues, because the future was created in the
root zone. (Well, originally, it was created in the first zone
which needed one, that was worse. Now it's created in the root zone.)
Some code tries to contain asynchrony inside a custom zone, and
then the get a `nullFuture` and calls `then` on it, and that
schedules a microtask in the root zone.
(It should probably have used the listener's zone, and not store
a zone in the future at all, but that's how it was first done,
and now people rely on that behavior too.)
This change creates a `null` future *per zone* (lazily initialized
when asked for). That should be sufficient because the code recognizing
a returned `null` future is generally running in the same zone,
but if any other code gets the `nullFuture`, it will be in the
expected zone for where it was requested.
This is a reland of commit a247b158d6
Change-Id: Ia113756de1f6d50af4b1abfec219d6b4dcd5d59b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/249488
Reviewed-by: Nate Bosch <nbosch@google.com>
Commit-Queue: Lasse Nielsen <lrn@google.com>
Front end for Dart
This package provides a low-level API for use by compiler back ends that wish to implement the Dart language. It is intended for eventual use by dev_compiler, dart2js, and the Dart VM. In addition, it will share implementation details with the analyzer package--this will be accomplished by having the analyzer package import (and re-export) parts of this package's private implementation.
End-users should use the dart analyze
command-line tool to analyze their Dart code.
Integrators that want to write tools that analyze Dart code should use the analyzer package.
Note: A previous version of this package was published on pub.dev. It has now been marked DISCONTINUED as it is not intended for direct consumption, as per the notes above.