v3.4.1

Compare Source

v3.4.0

Compare Source

Language

Dart 3.4 makes improvements to the type analysis of conditional expressions
(e1 ? e2 : e3), if-null expressions (e1 ?? e2), if-null assignments
(e1 ??= e2), and switch expressions (switch (e) { p1 => e1, ... }). To take
advantage of these improvements, set your package's
SDK constraint lower bound to 3.4 or greater
(sdk: '^3.4.0').

• Breaking Change #​54640: The pattern context type schema for
  cast patterns has been changed from Object? to _ (the unknown
  type), to align with the specification. This change is not expected
  to make any difference in practice.

• Breaking Change #​54828: The type schema used by the compiler front end
  to perform type inference on the operand of a null-aware spread operator
  (...?) in map and set literals has been made nullable, to match what
  currently happens in list literals. This makes the compiler front end behavior
  consistent with that of the analyzer. This change is expected to be very low
  impact.

Libraries

dart:async

• Added option for ParallelWaitError to get some meta-information that
  it can expose in its toString, and the Iterable<Future>.wait and
  (Future,...,Future).wait extension methods now provide that information.
  Should make a ParallelWaitError easier to log.

dart:cli

• Breaking change [#​52121][]: waitFor is removed in 3.4.

dart:ffi

• Added Struct.create and Union.create to create struct and union views
  of the sequence of bytes stored in a subtype of TypedData.

dart:io

• Breaking change #​53863: Stdout has a new field lineTerminator,
  which allows developers to control the line ending used by stdout and
  stderr. Classes that implement Stdout must define the lineTerminator
  field. The default semantics of stdout and stderr are not changed.

• Deprecates FileSystemDeleteEvent.isDirectory, which always returns
  false.

dart:js_interop

• Fixes an issue with several comparison operators in JSAnyOperatorExtension
  that were declared to return JSBoolean but really returned bool. This led
  to runtime errors when trying to use the return values. The implementation now
  returns a JSBoolean to align with the interface. See issue #​55024 for
  more details.

• Added ExternalDartReference and related conversion functions
  toExternalReference and toDartObject. This is a faster alternative to
  JSBoxedDartObject, but with fewer safety guarantees and fewer
  interoperability capabilities. See #​55187 for more details.

• On dart2wasm, JSBoxedDartObject now is an actual JS object that wraps the
  opaque Dart value instead of only externalizing the value. Like the JS
  backends, you'll now get a more useful error when trying to use it in another
  Dart runtime.

• Added isA helper to make type checks easier with interop types. See
  #​54138 for more details.

dart:typed_data

• BREAKING CHANGE #​53218 #​53785: The unmodifiable view classes for
  typed data are deprecated.

  To create an unmodifiable view of a typed-data object, use the
  asUnmodifiableView() methods added in Dart 3.3:

  Uint8List data = ...;
  final readOnlyView = data.asUnmodifiableView();
  // readOnlyView has type Uint8List, and throws if attempted modified.

  The reason for this change is to allow more flexibility in the implementation
  of typed data, so the native and web platforms can use different strategies
  to ensure that typed data has good performance.

  The deprecated types will be removed in Dart 3.5.

Tools

Analyzer

• Improved code completion. Fixed over 50% of completion correctness bugs,
  tagged analyzer-completion-correctness in the issue
  tracker.

• Support for new annotations introduced in version 1.14.0 of the meta
  package.

  • Support for the [@doNotSubmit][@​doNotSubmit] annotation, noting that any usage of an
    annotated member should not be submitted to source control.

  • Support for the [@mustBeConst][@​mustBeConst] annotation, which indicates that an
    annotated parameter only accepts constant arguments.

Linter

• Added the [unnecessary_library_name][unnecessary_library_name] lint.
• Added the [missing_code_block_language_in_doc_comment][missing_code_block_language_in_doc_comment] lint.

Compilers

• The compilation environment will no longer pretend to contain entries with
  value "" for all dart.library.foo strings, where dart:foo is not an
  available library. Instead there will only be entries for the available
  libraries, like dart.library.core, where the value was, and still is,
  "true". This should have no effect on const bool.fromEnvironment(...) or
  const String.fromEnvironment(...) without a defaultValue argument, an
  argument which was always ignored previously. It changes the behavior of
  const bool.hasEnvironment(...) on such an input, away from always being
  true and therefore useless.

DevTools

• Updated DevTools to version 2.33.0 from 2.31.1.
  To learn more, check out the release notes for versions
  2.32.0 and 2.33.0.

Pub

• Dependency resolution and dart pub outdated will now surface if a dependency
  is affected by a security advisory, unless the advisory is listed under a
  ignored_advisories section in the pubspec.yaml file. To learn more about
  pub's support for security advisories, visit
  dart.dev/go/pub-security-advisories.

• path-dependencies inside git-dependencies are now resolved relative to the
  git repo.

• All dart pub commands can now be run from any subdirectory of a project. Pub
  will find the first parent directory with a pubspec.yaml and operate
  relative it.

• New command dart pub unpack that downloads a package from pub.dev and
  extracts it to a subfolder of the current directory.

  This can be useful for inspecting the code, or playing with examples.

Dart Runtime

• Dart VM flags and options can now be provided to any executable generated
  using dart compile exe via the DART_VM_OPTIONS environment variable.
  DART_VM_OPTIONS should be set to a list of comma-separated flags and options
  with no whitespace. Options that allow for multiple values to be provided as
  comma-separated values are not supported (e.g.,
  --timeline-streams=Dart,GC,Compiler).

  Example of a valid DART_VM_OPTIONS environment variable:

  DART_VM_OPTIONS=--random_seed=42,--verbose_gc

• Dart VM no longer supports external strings: Dart_IsExternalString,
  Dart_NewExternalLatin1String and Dart_NewExternalUTF16String functions are
  removed from Dart C API.

v3.3.4

Compare Source

This is a patch release that:

• Fixes an issue with JS interop in dart2wasm where JS interop methods that used
  the enclosing library's @JS annotation were actually using the invocation's
  enclosing library's @JS annotation. (issue #​55430).

v3.3.3

Compare Source

This is a patch release that:

• Fixes an issue where dart vm crashed when running on pre-SSE41 older CPUs on Windows (issue #​55211).

v3.3.2

Compare Source

This is a patch release that:

• Fixes an issue in the CFE that placed some structural parameter references out
  of their context in the code restored from dill files, causing crashes in the
  incremental compiler whenever it restored a typedef from dill such that the
  typedef contained a generic function type on its right-hand side (issue
  #​55158).
• Fixes an issue in the CFE that prevented redirecting factories from being
  resolved in initializers of extension types (issue #​55194).
• Fixes an issues with VM's implementation of DateTime.timeZoneName
  on Windows, which was checking whether current date is in the summer or
  standard time rather than checking if the given moment is in the summer or
  standard time (issue #​55240).

v3.3.1

Compare Source

This is a patch release that:

• Fixes an issue in dart2js where object literal constructors in interop
  extension types would fail to compile without an @JS annotation on the
  library (issue #​55057).
• Disallows certain types involving extension types from being used as the
  operand of an await expression, unless the extension type itself implements
  Future (issue #​55095).

v3.3.0

Compare Source

Language

Dart 3.3 adds extension types to the language. To use them, set your
package's [SDK constraint][language version] lower bound to 3.3 or greater
(sdk: '^3.3.0').

Extension types

An extension type wraps an existing type with a different, static-only
interface. It works in a way which is in many ways similar to a class that
contains a single final instance variable holding the wrapped object, but
without the space and time overhead of an actual wrapper object.

Extension types are introduced by extension type declarations. Each
such declaration declares a new named type (not just a new name for the
same type). It declares a representation variable whose type is the
representation type. The effect of using an extension type is that the
representation (that is, the value of the representation variable) has
the members declared by the extension type rather than the members declared
by its "own" type (the representation type). Example:

extension type Meters(int value) {
  String get label => '${value}m';
  Meters operator +(Meters other) => Meters(value + other.value);
}

void main() {
  var m = Meters(42); // Has type `Meters`.
  var m2 = m + m; // OK, type `Meters`.
  // int i = m; // Compile-time error, wrong type.
  // m.isEven; // Compile-time error, no such member.
  assert(identical(m, m.value)); // Succeeds.
}

The declaration Meters is an extension type that has representation type
int. It introduces an implicit constructor Meters(int value); and a
getter int get value. m and m.value is the very same object, but m
has type Meters and m.value has type int. The point is that m
has the members of Meters and m.value has the members of int.

Extension types are entirely static, they do not exist at run time. If o
is the value of an expression whose static type is an extension type E
with representation type R, then o is just a normal object whose
run-time type is a subtype of R, exactly like the value of an expression
of type R. Also the run-time value of E is R (for example, E == R
is true). In short: At run time, an extension type is erased to the
corresponding representation type.

A method call on an expression of an extension type is resolved at
compile-time, based on the static type of the receiver, similar to how
extension method calls work. There is no virtual or dynamic dispatch. This,
combined with no memory overhead, means that extension types are zero-cost
wrappers around their representation value.

While there is thus no performance cost to using extension types, there is
a safety cost. Since extension types are erased at compile time, run-time
type tests on values that are statically typed as an extension type will
check the type of the representation object instead, and if the type check
looks like it tests for an extension type, like is Meters, it actually
checks for the representation type, that is, it works exactly like is int
at run time. Moreover, as mentioned above, if an extension type is used as
a type argument to a generic class or function, the type variable will be
bound to the representation type at run time. For example:

void main() {
  var meters = Meters(3);

  // At run time, `Meters` is just `int`.
  print(meters is int); // Prints "true".
  print(<Meters>[] is List<int>); // Prints "true".

  // An explicit cast is allowed and succeeds as well:
  List<Meters> meterList = <int>[1, 2, 3] as List<Meters>;
  print(meterList[1].label); // Prints "2m".
}

Extension types are useful when you are willing to sacrifice some run-time
encapsulation in order to avoid the overhead of wrapping values in
instances of wrapper classes, but still want to provide a different
interface than the wrapped object. An example of that is interop, where you
may have data that are not Dart objects to begin with (for example, raw
JavaScript objects when using JavaScript interop), and you may have large
collections of objects where it's not efficient to allocate an extra object
for each element.

Other changes

• Breaking Change #​54056: The rules for private field promotion have
  been changed so that an abstract getter is considered promotable if there are
  no conflicting declarations. There are no conflicting declarations if
  there are no non-final fields, external fields, concrete getters, or
  noSuchMethod forwarding getters with the same name in the same library.
  This makes the implementation more consistent and allows
  type promotion in a few rare scenarios where it wasn't previously allowed.
  It is unlikely, but this change could cause a breakage by changing
  an inferred type in a way that breaks later code. For example:

  class A {
    int? get _field;
  }
  class B extends A {
    final int? _field;
    B(this._field);
  }
  test(A a) {
    if (a._field != null) {
      var x = a._field; // Previously had type `int?`; now has type `int`
      ...
      x = null; // Previously allowed; now causes a compile-time error.
    }
  }

  Affected code can be fixed by adding an explicit type annotation.
  For example, in the above snippet, var x can be changed to int? x.

  It's also possible that some continuous integration configurations might fail
  if they have been configured to treat warnings as errors, because the expanded
  type promotion could lead to one of the following warnings:

  • unnecessary_non_null_assertion
  • unnecessary_cast
  • invalid_null_aware_operator

  These warnings can be addressed in the usual way, by removing the unnecessary
  operation in the first two cases, or changing ?. to . in the third case.

  To learn more about other rules surrounding type promotion,
  check out the guide on Fixing type promotion failures.

Libraries

dart:core

• String.fromCharCodes now allow start and end to be after the end of
  the Iterable argument, just like skip and take does on an Iterable.

dart:ffi

• In addition to functions, @Native can now be used on fields.
• Allow taking the address of native functions and fields via
  Native.addressOf.
• The elementAt pointer arithmetic extension methods on
  core Pointer types are now deprecated.
  Migrate to the new - and + operators instead.
• The experimental and deprecated @FfiNative annotation has been removed.
  Usages should be updated to use the @Native annotation.

dart:js_interop

• Breaking Change in the representation of JS types #​52687: JS types
  like JSAny were previously represented using a custom erasure of
  @staticInterop types that were compiler-specific. They are now represented
  as extension types where their representation types are compiler-specific.
  This means that user-defined @staticInterop types that implemented JSAny
  or JSObject can no longer do so and need to use
  JSObject.fromInteropObject. Going forward, it's recommended to use extension
  types to define interop APIs. Those extension types can still implement JS
  types.
• JSArray and JSPromise generics: JSArray and JSPromise are now generic
  types whose type parameter is a subtype of JSAny?. Conversions to and from
  these types are changed to account for the type parameters of the Dart or JS
  type, respectively.
• Breaking Change in names of extensions: Some dart:js_interop extension
  members are moved to different extensions on the same type or a supertype to
  better organize the API surface. See JSAnyUtilityExtension and
  JSAnyOperatorExtension for the new extensions. This shouldn't make a
  difference unless the extension names were explicitly used.
• Add importModule to allow users to dynamically import modules using the JS
  import() expression.

dart:js_interop_unsafe

• Add has helper to make hasProperty calls more concise.

dart:typed_data

• BREAKING CHANGE (https://github.com/dart-lang/sdk/issues/53218) The
  unmodifiable view classes for typed data are deprecated. Instead of using the
  constructors for these classes to create an unmodifiable view, e.g.

  Uint8List data = ...
  final readOnlyView = UnmodifiableUint8ListView(data);

  use the new asUnmodifiableView() methods:

  Uint8List data = ...
  final readOnlyView = data.asUnmodifiableView();

  The reason for this change is to allow more flexibility in the implementation
  of typed data so the native and web platforms can use different strategies
  for ensuring typed data has good performance.

  The deprecated types will be removed in a future Dart version.

dart:nativewrappers

• Breaking Change #​51896: The NativeWrapperClasses are marked base so
  that none of their subtypes can be implemented. Implementing subtypes can lead
  to crashes when passing such native wrapper to a native call, as it will try
  to unwrap a native field that doesn't exist.

Tools

Dart command line

• The dart create command now uses v3 of package:lints,
  including multiple new recommended lints by default.
  To learn more about the updated collection of lints,
  check out the package:lints 3.0.0 changelog entry.

DevTools

• Updated DevTools to version 2.31.1 from 2.28.1.
  To learn more, check out the release notes for versions
  2.29.0, 2.30.0,
  and 2.31.0.

Wasm compiler (dart2wasm)

• Breaking Change #​54004: dart:js_util, package:js, and dart:js
  are now disallowed from being imported when compiling with dart2wasm. Prefer
  using dart:js_interop and dart:js_interop_unsafe.

Development JavaScript compiler (DDC)

• Type arguments of package:js interop types are now printed as any instead
  of being omitted. This is simply a change to the textual representation of
  package js types that have type arguments. These type arguments are still
  completely ignored by the type system at runtime.

• Removed "implements <...>" text from the Chrome custom formatter display for
  Dart classes. This information provides little value and keeping it imposes an
  unnecessary maintenance cost.

Production JavaScript compiler (dart2js)

• Breaking Change #​54201:
  The Invocation that is passed to noSuchMethod will no longer have a
  minified memberName, even when dart2js is invoked with --minify.
  See #​54201 for more details.

Analyzer

• You can now suppress diagnostics in pubspec.yaml files by
  adding an # ignore: <diagnostic_id> comment.
• Invalid dart doc comment directives are now reported.
• The [flutter_style_todos][flutter_style_todos] lint now has a quick fix.

Linter

• Removed the iterable_contains_unrelated_type and
  list_remove_unrelated_type lints.
  Consider migrating to the expanded
  [collection_methods_unrelated_type][collection_methods_unrelated_type] lint.
• Removed various lints that are no longer necessary with sound null safety:
  • always_require_non_null_named_parameters
  • avoid_returning_null,
  • avoid_returning_null_for_future

v3.2.6

Compare Source

v3.2.5

Compare Source