chore(deps): update dependency dart to v3.9.0

[renovate]

This PR contains the following updates:

Package	Update	Change
dart (source)	minor	3.8.3 -> 3.9.0

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Release Notes

dart-lang/sdk (dart)

v3.9.0

Compare Source

Released on: 2025-08-13

Language

Dart 3.9 assumes null safety when computing type promotion, reachability, and
definite assignment. This makes these features produce more accurate results for
modern Dart programs. As a result of this change, more dead_code warnings may be
produced. To take advantage of these improvements, set your package's SDK
constraint lower bound to 3.9 or greater (sdk: '^3.9.0').

Tools

Analyzer

• The dart command-line tool commands that use the analysis server now run
  the AOT-compiled analysis server snapshot. These include dart analyze,
  dart fix, and dart language-server.

  There is no functional difference when using the AOT-compiled analysis server
  snapshot. But various tests indicate that there is a significant speedup in
  the time to analyze a project.

  In case of an incompatibility with the AOT-compiled snapshot, a
  --no-use-aot-snapshot flag may be passed to these commands. (Please file an
  issue with the appropriate project if you find that you need to use this
  flag! It will be removed in the future.) This flag directs the tool to revert
  to the old behavior, using the JIT-compiled analysis server snapshot. To
  direct the Dart Code plugin for VS Code to pass this flag, use the
  dart.analyzerAdditionalArgs setting. To direct the Dart
  IntelliJ plugin to pass this flag, use the dart.server.additional.arguments
  registry property, similar to these steps.

• Add the switch_on_type lint rule.

• Add the unnecessary_unawaited lint rule.

• Add an assist to convert a field formal parameter to a normal parameter.

Dart build

• Breaking change of feature in preview: dart build -f exe <target> is now
  dart build cli --target=<target>. See dart build cli --help for more info.

Dart Development Compiler (dartdevc)

• Outstanding async code now checks and cancels itself after a hot restart if
  it was started in a different generation of the application before the
  restart. This includes outstanding Futures created by calling
  JSPromise.toDart from thedart:js_interop and the underlying the
  dart:js_util helper promiseToFuture. Dart callbacks will not be run, but
  callbacks on the JavaScript side will still be executed.

• Fixed a soundness issue that allowed direct invocation of the value returned
  from a getter without any runtime checks when the getter's return type was a
  generic type argument instantiated as dynamic or Function.

  A getter defined as:

  class Container<T> {
    T get value => _value;
    ...
  }

  Could trigger the issue with a direct invocation:

  Container<dynamic>().value('Invocation with missing runtime checks!');

Dart native compiler

Added cross-compilation support for
target architectures of arm (ARM32) and riscv64 (RV64GC)
when the target OS is Linux.

Pub

• Git dependencies can now be version-solved based on git tags.

  Use a tag_pattern in the descriptor and a version constraint, and all
  commits matching the pattern will be considered during resolution. For
  example:

  dependencies:
    my_dependency:
      git:
        url: https://github.com/example/my_dependency
        tag_pattern: v{{version}}
      version: ^2.0.1

• Starting from language version 3.9 the flutter constraint upper bound is now
  respected in your root package. For example:

  name: my_app
  environment:
    sdk: ^3.9.0
    flutter: 3.33.0

  Results in dart pub get failing if invoked with a version of
  the Flutter SDK different from 3.33.0.

  The upper bound of the flutter constraint is still ignored in
  packages used as dependencies.
  https://github.com/flutter/flutter/issues/954725472 for details.

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✔️ Code generated!

Name	Link
🪓 Triggered by	0bc5d80a93e233d6830d167fa4c5739fe53ba2c6
🍃 Generated commit	a38de8030e8689c605672620deaa7f88fd814928
🌲 Generated branch	generated/renovate/dart-3.x