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

[renovate]

This PR contains the following updates:

Package	Update	Change
dart (source)	minor	3.7.3 -> 3.9.0

---

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.

v3.8.3

Compare Source

Released on: 2025-07-31

This is a patch release that:

• Fixes an issue with the DevTools Network screen and Hot Restart (issue flutter/devtools#9203)
• Fixes an issue when clearing the DevTools network screen (issue #​61187)

v3.8.2

Compare Source

Released on: 2025-07-16

This is a patch release that:

• Fixes an issue with the size of cross-compiled binaries (issue #​61097)

v3.8.1

Compare Source

Released on: 2025-05-28

This is a patch release that:

• Fixes an issue in DDC with late variables being incorrectly captured within
  async function bodies (issue #​60748).

v3.8.0

Compare Source

Released on: 2025-05-20

Language

Dart 3.8 adds null-aware elements to the language. To use them, set
your package's [SDK constraint][language version] lower bound to 3.8
or greater (sdk: '^3.8.0').

Null-aware elements

Null-aware elements make it easier to omit a value from a collection literal if
it's null. The syntax works in list literals, set literals, and map literals.
Within map literals, both null-aware keys and values are supported.
Here is an example a list literal written in both styles,
without using null-aware elements and using them:

String? lunch = isTuesday ? 'tacos!' : null;

var withoutNullAwareElements = [
  if (lunch != null) lunch,
  if (lunch.length != null) lunch.length!,
  if (lunch.length case var length?) length,
];

var withNullAwareElements = [
  ?lunch,
  ?lunch.length,
  ?lunch.length,
];

To learn more about null-aware collection elements,
check out the documentation
and the feature specification.

Libraries

dart:core

• Added Iterable.withIterator constructor.

dart:io

• Added HttpClientBearerCredentials.
• Updated Stdout.supportsAnsiEscapes and Stdin.supportsAnsiEscapes to
  return true for TERM containing tmux values.

dart:html

• Breaking change: Native classes in dart:html, like HtmlElement, can no
  longer be extended. Long ago, to support custom elements, element classes
  exposed a .created constructor that adhered to the v0.5 spec of web
  components. On this release, those constructors have been removed and with
  that change, the classes can no longer be extended. In a future change, they
  may be marked as interface classes as well. This is a follow up from an
  earlier breaking change in 3.0.0 that removed the registerElement APIs. See
  #​53264 for details.

dart:ffi

• Added Array.elements which exposes an Iterable over the Array's content.

Tools

Analyzer

• The analyzer now supports "doc imports," a new comment-based syntax which
  enables external elements to be referenced in documentation comments without
  actually importing them. See the
  documentation
  for details.
• Code completion is improved to offer more valid suggestions. In particular,
  the suggestions are improved when completing text in a comment reference on a
  documentation comment for an extension, a typedef, or a directive (an import,
  an export, or a library). Additionally, instance members can now be suggested
  in a documentation comment reference.
• Offer additional assist to wrap a Flutter widget with a FutureBuilder widget.
• Add a quick assist to wrap with ValueListenableBuilder.
• Add a quick fix to convert an (illegal) extension field declaration into a
  getter declaration.
• Add a quick fix to help code comply with a few lint rules that encourage
  omitting types: omit_local_variable_types,
  omit_obvious_local_variable_types, and omit_obvious_property_types.
• Add a quick fix to create an extension method to resolve an "undefined method
  invocation" error.
• Renaming a closure parameter is now possible.
• Renaming a field now adjusts implicit this references in order to avoid
  name collisions.
• Renaming a field formal parameter now properly renames known super-parameters
  in subclasses in other libraries.
• Renaming a method parameter now properly renames across the type hierarchy.
• The "encapsulate field" quick assist now works on final fields.
• The "inline method" refactoring now properly handles inner closures.
• The quick fix that adds names to a show clause or removes names from a
  hide clause can now add or remove multiple names simultaneously, in order to
  resolve as many "undefined" errors as possible.
• The "remove const" quick fix now operates on more types of code.
• The "add missing required argument" quick fix can now add multiple missing
  required arguments.
• Add a new warning that reports an import or export directive with multiple
  show or hide clauses, which are never necessary.
• Add a quick fix for this warning.
• Add LSP document links for lint rules in analysis options files.
• Add LSP document links for dependency packages in pubspec files.
• Fix various issues around patterns, like highlighting, navigation, and
  autocompletion.
• Add the use_null_aware_elements lint rule.
• Add the experimental unnecessary_ignore lint rule.
• (Thanks @​FMorschel for many of the above
  enhancements!)

Dart Development Compiler (dartdevc)

In order to align with dart2js semantics, DDC will now throw a runtime error
when a redirecting factory is torn off and one of its optional non-nullable
parameters is provided no value. The implicit null passed to the factory will
not match the non-nullable type and this will now throw.

In the future this will likely be a compile-time error and will be entirely
disallowed.

Dart to Javascript Compiler (dart2js)

Removed the --experiment-new-rti and --use-old-rti flags.

Dart native compiler

Added cross-compilation support for the
Linux x64 and Linux ARM64 target platforms.

Dart format

In 3.7.0, we released a largely rewritten formatter supporting a new
"tall" style. Since then, we've gotten a lot of feedback and bug
reports and made a number of fixes in response to that.

Features

Some users strongly prefer the old behavior where a trailing comma will be
preserved by the formatter and force the surrounding construct to split. That
behavior is supported again (but off by default) and can enabled by adding this
to a surrounding analysis_options.yaml file:

formatter:
  trailing_commas: preserve

This is similar to how trailing commas work in the old short style formatter
applied to code before language version 3.7.

Bug fixes

• Don't add a trailing comma in lists that don't allow it, even when there is
  a trailing comment (issue dart-lang/dart_style#1639).

Style changes

The following style changes are language versioned and only
affect code whose [language version][] is 3.8 or later.
Dart code at 3.7 or earlier is formatted the same as it was before.

• Allow more code on the same line as a named argument or =>.

  // Before:
  function(
    name:
        (param) => another(
          argument1,
          argument2,
        ),
  );
  
  // After:
  function(
    name: (param) => another(
      argument1,
      argument3,
    ),
  );

• Allow the target or property chain part of a split method chain on the RHS of
  =, :, and =>.

  // Before:
  variable =
      target.property
          .method()
          .another();
  
  // After:
  variable = target.property
      .method()
      .another();

• Allow the condition part of a split conditional expression on the RHS of =,
  :, and =>.

  // Before:
  variable =
      condition
      ? longThenBranch
      : longElseBranch;
  
  // After:
  variable = condition
      ? longThenBranch
      : longElseBranch;

• Don't indent conditional branches redundantly after =, :, and =>.

  // Before:
  function(
    argument:
        condition
            ? thenBranch
            : elseBranch,
  )
  
  // After:
  function(
    argument:
        condition
        ? thenBranch
        : elseBranch,
  )

• Indent conditional branches past the operators.

  // Before:
  condition
      ? thenBranch +
          anotherOperand
      : elseBranch(
        argument,
      );
  
  // After:
  condition
      ? thenBranch +
            anotherOperand
      : elseBranch(
          argument,
        );

• Block format record types in typedefs:

  // Before:
  typedef ExampleRecordTypedef =
      (
        String firstParameter,
        int secondParameter,
        String thirdParameter,
        String fourthParameter,
      );
  
  // After:
  typedef ExampleRecordTypedef = (
    String firstParameter,
    int secondParameter,
    String thirdParameter,
    String fourthParameter,
  );

• Eagerly split argument lists whose contents are complex enough to be easier
  to read spread across multiple lines even if they would otherwise fit on a
  single line.

  The heuristic is that the argument list must contain at least three named
  arguments, some of which are nested and some of which are not.

  // Before:
  TabBar(tabs: [Tab(text: 'A'), Tab(text: 'B')], labelColor: Colors.white70);
  
  // After:
  TabBar(
    tabs: [
      Tab(text: 'A'),
      Tab(text: 'B'),
    ],
    labelColor: Colors.white70,
  );

---

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