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## 3.6.0
### Language
- **Breaking Change** [#56065][]: The context used by the compiler and analyzer
to perform type inference on the operand of a `throw` expression has been
changed from the "unknown type" to `Object`. This makes the type system more
self-consistent, because it reflects the fact that it's not legal to throw
`null`. This change is not expected to make any difference in practice.
[#56065]: https://github.com/dart-lang/sdk/issues/56065
### Libraries
#### `dart:js_interop`
- Added constructors for `JSArrayBuffer`, `JSDataView`, and concrete typed array
types e.g. `JSInt8Array`.
- Added `length` and `[]`/`[]=` operators to `JSArray`.
- Added `toJSCaptureThis` so `this` is passed in from JavaScript to the
callback as the first parameter.
## 3.5.0
### Language
- **Breaking Change** [#55418][]: The context used by the compiler to perform
type inference on the operand of an `await` expression has been changed to
match the behavior of the analyzer. This change is not expected to make any
difference in practice.
- **Breaking Change** [#55436][]: The context used by the compiler to perform
type inference on the right hand side of an "if-null" expression (`e1 ?? e2`)
has been changed to match the behavior of the analyzer. change is expected to
have low impact on real-world code. But in principle it could cause
compile-time errors or changes in runtime behavior by changing inferred
types. The old behavior can be restored by supplying explicit types.
[#55418]: https://github.com/dart-lang/sdk/issues/55418
[#55436]: https://github.com/dart-lang/sdk/issues/55436
### Libraries
#### `dart:core`
- **Breaking Change** [#44876][]: `DateTime` on the web platform now stores
microseconds. The web implementation is now practically compatible with the
native implementation, where it is possible to round-trip a timestamp in
microseconds through a `DateTime` value without rounding the lower
digits. This change might be breaking for apps that rely in some way on the
`.microsecond` component always being zero, for example, expecting only three
fractional second digits in the `toString()` representation. Small
discrepancies in arithmetic due to rounding of web integers may still occur
for extreme values, (1) `microsecondsSinceEpoch` outside the safe range,
corresponding to dates with a year outside of 1685..2255, and (2) arithmetic
(`add`, `subtract`, `difference`) where the `Duration` argument or result
exceeds 570 years.
[#44876]: https://github.com/dart-lang/sdk/issues/44876
#### `dart:io`
- **Breaking Change** [#55786][]: `SecurityContext` is now `final`. This means
that `SecurityContext` can no longer be subclassed. `SecurityContext`
subclasses were never able to interoperate with other parts of `dart:io`.
- A `ConnectionTask` can now be created using an existing `Future<Socket>`.
Fixes [#55562].
[#55786]: https://github.com/dart-lang/sdk/issues/55786
[#55562]: https://github.com/dart-lang/sdk/issues/55562
#### `dart:typed_data`
- **Breaking Change** [#53785][]: The unmodifiable view classes for typed data
have been removed. These classes were deprecated in Dart 3.4.
To create an unmodifiable view of a typed-data object, use the
`asUnmodifiableView()` methods added in Dart 3.3.
- Added superinterface `TypedDataList` to typed data lists, implementing both
`List` and `TypedData`. Allows abstracting over all such lists without losing
access to either the `List` or the `TypedData` members.
A `ByteData` is still only a `TypedData`, not a list.
[#53785]: https://github.com/dart-lang/sdk/issues/53785
#### `dart:js_interop`
- **Breaking Change** [#55508][]: `importModule` now accepts a `JSAny` instead
of a `String` to support other JS values as well, like `TrustedScriptURL`s.
- **Breaking Change** [#55267][]: `isTruthy` and `not` now return `JSBoolean`
instead of `bool` to be consistent with the other operators.
- **Breaking Change** `ExternalDartReference` no longer implements `Object`.
`ExternalDartReference` now accepts a type parameter `T` with a bound of
`Object?` to capture the type of the Dart object that is externalized.
`ExternalDartReferenceToObject.toDartObject` now returns a `T`.
`ExternalDartReferenceToObject` and `ObjectToExternalDartReference` are now
extensions on `T` and `ExternalDartReference<T>`, respectively, where `T
extends Object?`. See [#55342][] and [#55536][] for more details.
- Fixed some consistency issues with `Function.toJS` across all compilers.
Specifically, calling `Function.toJS` on the same function gives you a new JS
function (see issue [#55515][]), the maximum number of arguments that are
passed to the JS function is determined by the static type of the Dart
function, and extra arguments are dropped when passed to the JS function in
all compilers (see [#48186][]).
[#55508]: https://github.com/dart-lang/sdk/issues/55508
[#55267]: https://github.com/dart-lang/sdk/issues/55267
[#55342]: https://github.com/dart-lang/sdk/issues/55342
[#55536]: https://github.com/dart-lang/sdk/issues/55536
[#55515]: https://github.com/dart-lang/sdk/issues/55515
[#48186]: https://github.com/dart-lang/sdk/issues/48186
### Tools
#### Linter
- Added the [`unintended_html_in_doc_comment`][] lint.
- Added the [`invalid_runtime_check_with_js_interop_types`][] lint.
- Added the [`document_ignores`][] lint.
[`unintended_html_in_doc_comment`]: https://dart.dev/lints/unintended_html_in_doc_comment
[`invalid_runtime_check_with_js_interop_types`]: https://dart.dev/lints/invalid_runtime_check_with_js_interop_types
[`document_ignores`]: https://dart.dev/lints/document_ignores
#### Pub
- New flag `dart pub downgrade --tighten` to restrict lower bounds of
dependencies' constraints to the minimum that can be resolved.
### Dart Runtime
- The Dart VM only executes sound null safe code, running of unsound null
safe code using the option `--no-sound-null-safety` has been removed.
- `Dart_NewListOf` and `Dart_IsLegacyType` functions are
removed from Dart C API.
- `Dart_DefaultCanonicalizeUrl` is removed from the Dart C API.
## 3.4.0
### 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][language version] lower bound to 3.4 or greater
(`sdk: '^3.4.0'`).
[language version]: https://dart.dev/guides/language/evolution
- **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.
[#54640]: https://github.com/dart-lang/sdk/issues/54640
[#54828]: https://github.com/dart-lang/sdk/issues/54828
### 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`.
[#53863]: https://github.com/dart-lang/sdk/issues/53863
#### `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.
[#54138]: https://github.com/dart-lang/sdk/issues/54138
[#55024]: https://github.com/dart-lang/sdk/issues/55024
[#55187]: https://github.com/dart-lang/sdk/issues/55187
#### `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:
```dart
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.
[#53218]: https://github.com/dart-lang/sdk/issues/53218
[#53785]: https://github.com/dart-lang/sdk/issues/53785
### Tools
#### Analyzer
- Improved code completion. Fixed over 50% of completion correctness bugs,
tagged `analyzer-completion-correctness` in the [issue
tracker][analyzer-completion-correction-issues].
- Support for new annotations introduced in version 1.14.0 of the [meta]
package.
- Support for the [`@doNotSubmit`] annotation, noting that any usage of an
annotated member should not be submitted to source control.
- Support for the [`@mustBeConst`] annotation, which indicates that an
annotated parameter only accepts constant arguments.
[analyzer-completion-correction-issues]: https://github.com/dart-lang/sdk/labels/analyzer-completion-correctness
[meta]: https://pub.dev/packages/meta
[`@doNotSubmit`]: https://pub.dev/documentation/meta/latest/meta/doNotSubmit-constant.html
[`@mustBeConst`]: https://pub.dev/documentation/meta/latest/meta/mustBeConst-constant.html
#### Linter
- Added the [`unnecessary_library_name`][] lint.
- Added the [`missing_code_block_language_in_doc_comment`][] lint.
[`unnecessary_library_name`]: https://dart.dev/lints/unnecessary_library_name
[`missing_code_block_language_in_doc_comment`]: https://dart.dev/lints/missing_code_block_language_in_doc_comment
#### 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][devtools-2-32-0] and [2.33.0][devtools-2-33-0].
[devtools-2-32-0]: https://docs.flutter.dev/tools/devtools/release-notes/release-notes-2.32.0
[devtools-2-33-0]: https://docs.flutter.dev/tools/devtools/release-notes/release-notes-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][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.
[pub-security-advisories]: https://dart.dev/go/pub-security-advisories
### 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:
```bash
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.
## 3.3.4 - 2024-04-17
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]).
[#55430]: https://github.com/dart-lang/sdk/issues/55430
## 3.3.3 - 2024-03-27
This is a patch release that:
- Fixes an issue where dart vm crashed when running on pre-SSE41 older CPUs on Windows (issue [#55211][]).
[#55211]: https://github.com/dart-lang/sdk/issues/55211
## 3.3.2 - 2024-03-20
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][]).
[#55158]: https://github.com/dart-lang/sdk/issues/55158
[#55194]: https://github.com/dart-lang/sdk/issues/55194
[#55240]: https://github.com/dart-lang/sdk/issues/55240
## 3.3.1 - 2024-03-06
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][]).
[#55057]: https://github.com/dart-lang/sdk/issues/55057
[#55095]: https://github.com/dart-lang/sdk/issues/55095
## 3.3.0
### 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
[extension types]: https://github.com/dart-lang/language/issues/2727
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:
```dart
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:
```dart
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:
```dart
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][].
[#54056]: https://github.com/dart-lang/sdk/issues/54056
[Fixing type promotion failures]: https://dart.dev/tools/non-promotion-reasons
### 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.
[#52687]: https://github.com/dart-lang/sdk/issues/52687
#### `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.
```dart
Uint8List data = ...
final readOnlyView = UnmodifiableUint8ListView(data);
```
use the new `asUnmodifiableView()` methods:
```dart
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.
[#51896]: https://github.com/dart-lang/sdk/issues/51896
### 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][lints-3-0].
[lints-3-0]: https://pub.dev/packages/lints/changelog#300
#### 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][devtools-2-29-0], [2.30.0][devtools-2-30-0],
and [2.31.0][devtools-2-31-0].
[devtools-2-29-0]: https://docs.flutter.dev/tools/devtools/release-notes/release-notes-2.29.0
[devtools-2-30-0]: https://docs.flutter.dev/tools/devtools/release-notes/release-notes-2.30.0
[devtools-2-31-0]: https://docs.flutter.dev/tools/devtools/release-notes/release-notes-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`.
[#54004]: https://github.com/dart-lang/sdk/issues/54004
#### 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.
[#54201]: https://github.com/dart-lang/sdk/issues/54201
#### 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`][] lint now has a quick fix.
[`flutter_style_todos`]: https://dart.dev/lints/flutter_style_todos
#### Linter
- Removed the `iterable_contains_unrelated_type` and
`list_remove_unrelated_type` lints.
Consider migrating to the expanded
[`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`
[`collection_methods_unrelated_type`]: https://dart.dev/lints/collection_methods_unrelated_type
## 3.2.3 - 2023-12-06
This is a patch release that:
- Disallows final fields to be used in a constant context during analysis
(issue [#54232][]).
- Upgrades Dart DevTools to version 2.28.4 (issue [#54213][]).
- Fixes new AOT snapshots in the SDK failing with SIGILL in ARM
environments that don't support the integer division
instructions or x86-64 environments that don't support
SSE4.1 (issue [#54215][]).
[#54232]: https://github.com/dart-lang/sdk/issues/54232
[#54213]: https://github.com/dart-lang/sdk/issues/54213
[#54215]: https://github.com/dart-lang/sdk/issues/54215
## 3.2.2 - 2023-11-29
This is a patch release that:
- Adjusts the nullablity computations in the implementation of the
upper bound algorithm in the compiler frontend (issue [#53999][]).
- Fixes missing closure code completion entries for function parameters
for LSP-based editors like VS Code (issue [#54112][]).
[#53999]: https://github.com/dart-lang/sdk/issues/53999
[#54112]: https://github.com/dart-lang/sdk/issues/54112
## 3.2.1 - 2023-11-22
This is a patch release that:
- Fixes the left/mobile sidebar being empty on non-class pages
in documentation generated with `dart doc` (issue [#54073][]).
- Fixes a JSON array parsing bug that causes a segmentation fault when
`flutter test` is invoked with the `--coverage` flag
(SDK issue [#54059][], Flutter issue [#124145][]).
- Upgrades Dart DevTools to version 2.28.3 (issue [#54085][]).
[#54073]: https://github.com/dart-lang/sdk/issues/54073
[#54059]: https://github.com/dart-lang/sdk/issues/54059
[#124145]: https://github.com/flutter/flutter/issues/124145
[#54085]: https://github.com/dart-lang/sdk/issues/54085
## 3.2.0 - 2023-11-15
### Language
Dart 3.2 adds the following features. To use them, set your package's [SDK
constraint][language version] lower bound to 3.2 or greater (`sdk: '^3.2.0'`).
[language version]: https://dart.dev/guides/language/evolution
- **Private field promotion**: In most circumstances, the types of private final
fields can now be promoted by null checks and `is` tests. For example:
```dart
class Example {
final int? _privateField;
Example(this._privateField);
f() {
if (_privateField != null) {
// _privateField has now been promoted; you can use it without
// null checking it.
int i = _privateField; // OK
}
}
}
// Private field promotions also work from outside of the class:
f(Example x) {
if (x._privateField != null) {
int i = x._privateField; // OK
}
}
```
To ensure soundness, a field is not eligible for field promotion in the
following circumstances:
- If it's not final (because a non-final field could be changed in between the
test and the usage, invalidating the promotion).
- If it's overridden elsewhere in the library by a concrete getter or a
non-final field (because an access to an overridden field might resolve at
runtime to the overriding getter or field).
- If it's not private (because a non-private field might be overridden
elsewhere in the program).
- If it has the same name as a concrete getter or a non-final field in some
other unrelated class in the library (because a class elsewhere in the
program might extend one of the classes and implement the other, creating an
override relationship between them).
- If there is a concrete class `C` in the library whose interface contains a
getter with the same name, but `C` does not have an implementation of that
getter (such unimplemented getters aren't safe for field promotion, because
they are implicitly forwarded to `noSuchMethod`, which might not return the
same value each time it's called).
- **Breaking Change** [#53167][]: Use a more precise split point for refutable
patterns. Previously, in an if-case statement, if flow analysis could prove
that the scrutinee expression was guaranteed to throw an exception, it would
sometimes fail to propagate type promotions implied by the pattern to the
(dead) code that follows. This change makes the type promotion behavior of
if-case statements consistent regardless of whether the scrutinee expression
throws an exception.
No live code is affected by this change, but there is a small chance that the
change in types will cause a compile-time error to appear in some dead code in
the user's project, where no compile-time error appeared previously.
[#53167]: https://github.com/dart-lang/sdk/issues/53167
### Libraries
#### `dart:async`
- Added `broadcast` parameter to `Stream.empty` constructor.
#### `dart:cli`
- **Breaking change** [#52121][]:
- `waitFor` is disabled by default and slated for removal in 3.4. Attempting
to call this function will now throw an exception. Users that still depend
on `waitFor` can enable it by passing `--enable_deprecated_wait_for` flag
to the VM.
[#52121]: https://github.com/dart-lang/sdk/issues/52121
#### `dart:convert`
- **Breaking change** [#52801][]:
- Changed return types of `utf8.encode()` and `Utf8Codec.encode()` from
`List<int>` to `Uint8List`.
[#52801]: https://github.com/dart-lang/sdk/issues/52801
#### `dart:developer`
- Deprecated the `Service.getIsolateID` method.
- Added `getIsolateId` method to `Service`.
- Added `getObjectId` method to `Service`.
#### `dart:ffi`
- Added the `NativeCallable.isolateLocal` constructor. This creates
`NativeCallable`s with the same functionality as `Pointer.fromFunction`,
except that `NativeCallable` accepts closures.
- Added the `NativeCallable.keepIsolateAlive` method, which determines whether
the `NativeCallable` keeps the isolate that created it alive.
- All `NativeCallable` constructors can now accept closures. Previously
`NativeCallable`s had the same restrictions as `Pointer.fromFunction`, and
could only create callbacks for static functions.
- **Breaking change** [#53311][]: `NativeCallable.nativeFunction` now throws an
error if is called after the `NativeCallable` has already been `close`d. Calls
to `close` after the first are now ignored.
[#53311]: https://github.com/dart-lang/sdk/issues/53311
#### `dart:io`
- **Breaking change** [#53005][]: The headers returned by
`HttpClientResponse.headers` and `HttpRequest.headers` no longer include
trailing whitespace in their values.
- **Breaking change** [#53227][]: Folded headers values returned by
`HttpClientResponse.headers` and `HttpRequest.headers` now have a space
inserted at the fold point.
[#53005]: https://dartbug.com/53005
[#53227]: https://dartbug.com/53227
#### `dart:isolate`
- Added `Isolate.packageConfigSync` and `Isolate.resolvePackageUriSync` APIs.
#### `dart:js_interop`
- **Breaking Change on JSNumber.toDart and Object.toJS**:
`JSNumber.toDart` is removed in favor of `toDartDouble` and `toDartInt` to
make the type explicit. `Object.toJS` is also removed in favor of
`Object.toJSBox`. Previously, this function would allow Dart objects to flow
into JS unwrapped on the JS backends. Now, there's an explicit wrapper that is
added and unwrapped via `JSBoxedDartObject.toDart`. Similarly,
`JSExportedDartObject` is renamed to `JSBoxedDartObject` and the extensions
`ObjectToJSExportedDartObject` and `JSExportedDartObjectToObject` are renamed
to `ObjectToJSBoxedDartObject` and `JSBoxedDartObjectToObject` in order to
avoid confusion with `@JSExport`.
- **Type parameters in external APIs**:
Type parameters must now be bound to a static interop type or one of the
`dart:js_interop` types like `JSNumber` when used in an external API. This
only affects `dart:js_interop` classes and not `package:js` or other forms of
JS interop.
- **Subtyping `dart:js_interop` types**:
`@staticInterop` types can subtype only `JSObject` and `JSAny` from the set of
JS types in `dart:js_interop`. Subtyping other types from `dart:js_interop`
would result in confusing type errors before, so this makes it a static error.
- **Global context of `dart:js_interop` and `@staticInterop` APIs**:
Static interop APIs will now use the same global context as non-static interop
instead of `globalThis` to avoid a greater migration. Static interop APIs,
either through `dart:js_interop` or the `@staticInterop` annotation, have used
JavaScript's `globalThis` as the global context. This is relevant to things
like external top-level members or external constructors, as this is the root
context we expect those members to reside in. Historically, this was not the
case in dart2js and DDC. We used either `self` or DDC's `global` in non-static
interop APIs with `package:js`. So, static interop APIs will now use one of
those global contexts. Functionally, this should matter in only a very small
number of cases, like when using older browser versions. `dart:js_interop`'s
`globalJSObject` is also renamed to `globalContext` and returns the global
context used in the lowerings.
- **Breaking Change on Types of `dart:js_interop` External APIs**:
External JS interop APIs when using `dart:js_interop` are restricted to a set
of allowed types. Namely, this includes the primitive types like `String`, JS
types from `dart:js_interop`, and other static interop types (either through
`@staticInterop` or extension types).
- **Breaking Change on `dart:js_interop` `isNull` and `isUndefined`**:
`null` and `undefined` can only be discerned in the JS backends. dart2wasm
conflates the two values and treats them both as Dart null. Therefore, these
two helper methods should not be used on dart2wasm and will throw to avoid
potentially erroneous code.
- **Breaking Change on `dart:js_interop` `typeofEquals` and `instanceof`**:
Both APIs now return a `bool` instead of a `JSBoolean`. `typeofEquals` also
now takes in a `String` instead of a `JSString`.
- **Breaking Change on `dart:js_interop` `JSAny` and `JSObject`**:
These types can only be implemented, and no longer extended, by user
`@staticInterop` types.
- **Breaking Change on `dart:js_interop` `JSArray.withLength`**:
This API now takes in an `int` instead of `JSNumber`.
### Tools
#### Development JavaScript compiler (DDC)
- Applications compiled by DDC will no longer add members to the native
JavaScript Object prototype.
- **Breaking change for JS interop with Symbols and BigInts**:
JavaScript `Symbol`s and `BigInt`s are now associated with their own
interceptor and should not be used with `package:js` classes. These types were
being intercepted with the assumption that they are a subtype of JavaScript's
`Object`, but this is incorrect. This lead to erroneous behavior when using
these types as Dart `Object`s. See [#53106][] for more details. Use
`dart:js_interop`'s `JSSymbol` and `JSBigInt` with extension types to interop
with these types.
#### Production JavaScript compiler (dart2js)
- **Breaking change for JS interop with Symbols and BigInts**:
JavaScript `Symbol`s and `BigInt`s are now associated with their own
interceptor and should not be used with `package:js` classes. These types were
being intercepted with the assumption that they are a subtype of JavaScript's
`Object`, but this is incorrect. This lead to erroneous behavior when using
these types as Dart `Object`s. See [#53106][] for more details. Use
`dart:js_interop`'s `JSSymbol` and `JSBigInt` with extension types to interop
with these types.
[#53106]: https://github.com/dart-lang/sdk/issues/53106
#### Dart command line
- The `dart create` command has a new `cli` template
to quickly create Dart command-line applications
with basic argument parsing capabilities.
To learn more about using the template,
run `dart help create`.
#### Dart format
- Always split enum declarations containing a line comment.
- Fix regression in splitting type annotations with library prefixes.
- Support `--enable-experiment` command-line option to enable language
experiments.
#### DevTools
- Incorporated the [2.26.1][devtools-2-26-1], [2.27.0][devtools-2-27-0], and
[2.28.1][devtools-2-28-1] releases of DevTools.
[devtools-2-26-1]: https://docs.flutter.dev/tools/devtools/release-notes/release-notes-2.26.1
[devtools-2-27-0]: https://docs.flutter.dev/tools/devtools/release-notes/release-notes-2.27.0
[devtools-2-28-1]: https://docs.flutter.dev/tools/devtools/release-notes/release-notes-2.28.1
#### Linter
- Added the experimental [`annotate_redeclares`][] lint.
- Marked the [`use_build_context_synchronously`][] lint as stable.
[`annotate_redeclares`]: https://dart.dev/lints/annotate_redeclares
[`use_build_context_synchronously`]: https://dart.dev/lints/use_build_context_synchronously
#### Pub
- New option `dart pub upgrade --tighten` which will update dependencies' lower
bounds in `pubspec.yaml` to match the current version.
- The commands `dart pub get`/`add`/`upgrade` will now show if a dependency
changed between direct, dev and transitive dependency.
- The command `dart pub upgrade` no longer shows unchanged dependencies.
## 3.1.5 - 2023-10-25
This is a patch release that:
- Fixes an issue affecting Dart compiled to JavaScript running in Node.js 21. A
change in Node.js 21 affected the Dart Web compiler runtime. This patch
release accommodates for those changes (issue #53810).
[#53810]: https://github.com/dart-lang/sdk/issues/53810
## 3.1.4 - 2023-10-18
This is a patch release that:
- Fixes an issue in the Dart VM, users are not being able to see
value of variables while debugging code (issue [#53747]).
[#53654]: https://github.com/dart-lang/sdk/issues/53747
## 3.1.3 - 2023-09-27
This is a patch release that:
- Fixes a bug in dart2js which would cause the compiler to crash when using
`@staticInterop` `@anonymous` factory constructors with type parameters (see
issue [#53579] for more details).
- The standalone Dart VM now exports symbols only for the Dart_* embedding API
functions, avoiding conflicts with other DSOs loaded into the same process,
such as shared libraries loaded through `dart:ffi`, that may have different
versions of the same symbols (issue [#53503]).
- Fixes an issue with super slow access to variables while debugging.
The fix avoids searching static functions in the imported libraries
as references to members are fully resolved by the front-end. (issue
[#53541])
[#53579]: https://github.com/dart-lang/sdk/issues/53579
[#53267]: https://github.com/dart-lang/sdk/issues/53503
[#53541]: https://github.com/dart-lang/sdk/issues/53541
## 3.1.2 - 2023-09-13
This is a patch release that:
- Fixes a bug in dart2js which crashed the compiler when a typed record pattern
was used outside the scope of a function body, such as in a field initializer.
For example `final x = { for (var (int a,) in someList) a: a };`
(issue [#53449])
- Fixes an expedient issue of users seeing an unhandled
exception pause in the debugger, please see
https://github.com/dart-lang/sdk/issues/53450 for more
details.
The fix uses try/catch in lookupAddresses instead of
Future error so that we don't see an unhandled exception
pause in the debugger (issue [#53450])
[#53449]: https://github.com/dart-lang/sdk/issues/53449
[#53450]: https://github.com/dart-lang/sdk/issues/53450
## 3.1.1 - 2023-09-07
This is a patch release that:
- Fixes a bug in the parser which prevented a record pattern from containing a
nested record pattern, where the nested record pattern uses record
destructuring shorthand syntax, for example `final ((:a, :b), c) = record;`
(issue [#53352]).
[#53352]: https://github.com/dart-lang/sdk/issues/53352
## 3.1.0 - 2023-08-16
### Libraries
#### `dart:async`
- **Breaking change** [#52334][]:
- Added the `interface` modifier to purely abstract classes:
`MultiStreamController`, `StreamConsumer`, `StreamIterator` and
`StreamTransformer`. As a result, these types can only be implemented,
not extended or mixed in.
[#52334]: https://github.com/dart-lang/sdk/issues/52334
#### `dart:core`
- `Uri.base` on native platforms now respects `IOOverrides` overriding
current directory ([#39796][]).
[#39796]: https://github.com/dart-lang/sdk/issues/39796
#### `dart:ffi`
- Added the `NativeCallable` class, which can be used to create callbacks that
allow native code to call into Dart code from any thread. See
`NativeCallable.listener`. In future releases, `NativeCallable` will be
updated with more functionality, and will become the recommended way of
creating native callbacks for all use cases, replacing `Pointer.fromFunction`.
#### `dart:io`
- **Breaking change** [#51486][]:
- Added `sameSite` to the `Cookie` class.
- Added class `SameSite`.
- **Breaking change** [#52027][]: `FileSystemEvent` is
[`sealed`](https://dart.dev/language/class-modifiers#sealed). This means
that `FileSystemEvent` cannot be extended or implemented.
- Added a deprecation warning when `Platform` is instantiated.
- Added `Platform.lineTerminator` which exposes the character or characters
that the operating system uses to separate lines of text, e.g.,
`"\r\n"` on Windows.
[#51486]: https://github.com/dart-lang/sdk/issues/51486
[#52027]: https://github.com/dart-lang/sdk/issues/52027
#### `dart:js_interop`
- **Object literal constructors**:
`ObjectLiteral` is removed from `dart:js_interop`. It's no longer needed in
order to declare an object literal constructor with inline classes. As long as
an external constructor has at least one named parameter, it'll be treated as
an object literal constructor. If you want to create an object literal with no
named members, use `{}.jsify()`.
### Other libraries
#### `package:js`
- **Breaking change to `@staticInterop` and `external` extension members**:
`external` `@staticInterop` members and `external` extension members can no
longer be used as tear-offs. Declare a closure or a non-`external` method that
calls these members, and use that instead.
- **Breaking change to `@staticInterop` and `external` extension members**:
`external` `@staticInterop` members and `external` extension members will
generate slightly different JS code for methods that have optional parameters.
Whereas before, the JS code passed in the default value for missing optionals,
it will now pass in only the provided members. This aligns with how JS
parameters work, where omitted parameters are actually omitted. For example,
calling `external void foo([int a, int b])` as `foo(0)` will now result in
`foo(0)`, and not `foo(0, null)`.
### Tools
#### DevTools
- Incorporated the [2.24.0][devtools-2-24-0] and [2.25.0][devtools-2-25-0]
releases of DevTools.
[devtools-2-24-0]: https://docs.flutter.dev/tools/devtools/release-notes/release-notes-2.24.0
[devtools-2-25-0]: https://docs.flutter.dev/tools/devtools/release-notes/release-notes-2.25.0
#### Linter
- Added new static analysis lints you can [enable][enable-lints] in
your package's `analysis_options.yaml` file:
- [`no_self_assignments`](https://dart.dev/lints/no_self_assignments)
- [`no_wildcard_variable_uses`](https://dart.dev/lints/no_wildcard_variable_uses)
[enable-lints]: https://dart.dev/tools/analysis#enabling-linter-rules
## 3.0.7 - 2023-07-26
This is a patch release that:
- Fixes a bug in dart2js which would cause certain uses of records to lead to
bad codegen causing a `TypeError` or `NoSuchMethodError` to be thrown
at runtime (issue [#53001]).
[#53001]: https://github.com/dart-lang/sdk/issues/53001
## 3.0.6 - 2023-07-12
This is a patch release that:
- Fixes a flow in flow analysis that causes it to sometimes ignore destructuring
assignments (issue [#52767]).
- Fixes an infinite loop in some web development compiles that include `is` or
`as` expressions involving record types with named fields (issue [#52869]).
- Fixes a memory leak in Dart analyzer's file-watching (issue [#52791]).
- Fixes a memory leak of file system watcher related data structures (issue [#52793]).
[#52767]: https://github.com/dart-lang/sdk/issues/52767
[#52869]: https://github.com/dart-lang/sdk/issues/52869
[#52791]: https://github.com/dart-lang/sdk/issues/52791
[#52793]: https://github.com/dart-lang/sdk/issues/52793
## 3.0.5 - 2023-06-14
This is a patch release that:
- Fixes a bad cast in the frontend which can manifest as a crash in the dart2js
`ListFactorySpecializer` during Flutter web builds (issue [#52403]).
[#52403]: https://github.com/dart-lang/sdk/issues/52403
## 3.0.4 - 2023-06-07
This is a patch release that:
- `dart format` now handles formatting nullable record types
with no fields (dart_style issue [#1224]).
- Fixes error when using records when targeting the web in development mode
(issue [#52480]).
[#1224]: https://github.com/dart-lang/dart_style/issues/1224
[#52480]: https://github.com/dart-lang/sdk/issues/52480
## 3.0.3 - 2023-02-07
This is a patch release that:
- Fixes an AOT compiler crash when generating an implicit getter
returning an unboxed record (issue [#52449]).
- Fixes a situation in which variables appearing in multiple branches of an
or-pattern might be erroneously reported as being mismatched (issue [#52373]).
- Adds missing `interface` modifiers on the purely abstract classes
`MultiStreamController`, `StreamConsumer`, `StreamIterator` and
`StreamTransformer` (issue [#52334]).
- Fixes an error during debugging when `InternetAddress.tryParse` is
used (issue [#52423]).
- Fixes a VM issue causing crashes on hot reload (issue [#126884]).
- Improves linter support (issue [#4195]).
- Fixes an issue in variable patterns preventing users from expressing
a pattern match using a variable or wildcard pattern with a nullable
record type (issue [#52439]).
- Updates warnings and provide instructions for updating the Dart pub
cache on Windows (issue [#52386]).
[#52373]: https://github.com/dart-lang/sdk/issues/52373
[#52334]: https://github.com/dart-lang/sdk/issues/52334
[#52423]: https://github.com/dart-lang/sdk/issues/52423
[#126884]: https://github.com/flutter/flutter/issues/126884
[#4195]: https://github.com/dart-lang/linter/issues/4195
[#52439]: https://github.com/dart-lang/sdk/issues/52439
[#52449]: https://github.com/dart-lang/sdk/issues/52449
[#52386]: https://github.com/dart-lang/sdk/issues/52386
## 3.0.2 - 2023-05-24
This is a patch release that:
- Fixes a dart2js crash when using a switch case expression on a record where
the fields don't match the cases (issue [#52438]).
- Add class modifier chips on class and mixin pages
generated with `dart doc` (issue [#3392]).
- Fixes a situation causing the parser to fail resulting in an infinite loop
leading to higher memory usage (issue [#52352]).
- Add clear errors when mixing inheritance in pre and post Dart 3 libraries
(issue: [#52078]).
[#52438]: https://github.com/dart-lang/sdk/issues/52438
[#3392]: https://github.com/dart-lang/dartdoc/issues/3392
[#52352]: https://github.com/dart-lang/sdk/issues/52352
[#52078]: https://github.com/dart-lang/sdk/issues/52078
## 3.0.1 - 2023-05-17
This is a patch release that:
- Fixes a compiler crash involving redirecting factories and FFI
(issue [#124369]).
- Fixes a dart2js crash when using a combination of local functions, generics,
and records (issue [#51899]).
- Fixes incorrect error using a `void` in a switch case expression
(issue [#52191]).
- Fixes a false error when using in switch case expressions when the switch
refers to a private getter (issue [#52041]).
- Prevent the use of `when` and `as` as variable names in patterns
(issue [#52260]).
- Fixes an inconsistency in type promotion between the analyzer and VM
(issue [#52241]).
- Improve performance on functions with many parameters (issue [#1212]).
[#124369]: https://github.com/flutter/flutter/issues/124369
[#51899]: https://github.com/dart-lang/sdk/issues/51899
[#52191]: https://github.com/dart-lang/sdk/issues/52191
[#52041]: https://github.com/dart-lang/sdk/issues/52041
[#52260]: https://github.com/dart-lang/sdk/issues/52260
[#52241]: https://github.com/dart-lang/sdk/issues/52241
[#1212]: https://github.com/dart-lang/dart_style/issues/1212
## 3.0.0 - 2023-05-10
### Language
Dart 3.0 adds the following features. To use them, set your package's [SDK
constraint][language version] lower bound to 3.0 or greater (`sdk: '^3.0.0'`).
[language version]: https://dart.dev/guides/language/evolution
- **[Records]**: Records are anonymous immutable data structures that let you
aggregate multiple values together, similar to [tuples][] in other languages.
With records, you can return multiple values from a function, create composite
map keys, or use them any other place where you want to bundle a couple of
objects together.
For example, using a record to return two values:
```dart
(double x, double y) geoLocation(String name) {
if (name == 'Nairobi') {
return (-1.2921, 36.8219);
} else {
...
}
}
```
- **[Pattern matching]**: Expressions build values out of smaller pieces.
Conversely, patterns are an expressive tool for decomposing values back into
their constituent parts. Patterns can call getters on an object, access
elements from a list, pull fields out of a record, etc. For example, we can
destructure the record from the previous example like so:
```dart
var (lat, long) = geoLocation('Nairobi');
print('Nairobi is at $lat, $long.');
```
Patterns can also be used in [switch cases]. There, you can destructure values
and also test them to see if they have a certain type or value:
```dart
switch (object) {
case [int a]:
print('A list with a single integer element $a');
case ('name', _):
print('A two-element record whose first field is "name".');
default: print('Some other object.');
}
```
Also, as you can see, non-empty switch cases no longer need `break;`
statements.
**Breaking change**: Dart 3.0 interprets [switch cases] as patterns instead of
constant expressions. Most constant expressions found in switch cases are
valid patterns with the same meaning (named constants, literals, etc.). You
may need to tweak a few constant expressions to make them valid. This only
affects libraries that have upgraded to language version 3.0.
- **[Switch expressions]**: Switch expressions allow you to use patterns and
multi-way branching in contexts where a statement isn't allowed:
```dart
return TextButton(
onPressed: _goPrevious,
child: Text(switch (page) {
0 => 'Exit story',
1 => 'First page',
_ when page == _lastPage => 'Start over',
_ => 'Previous page',
}),
);
```
- **[If-case statements and elements]**: A new if construct that matches a value
against a pattern and executes the then or else branch depending on whether
the pattern matches:
```dart
if (json case ['user', var name]) {
print('Got user message for user $name.');
}
```
There is also a corresponding [if-case element] that can be used in collection
literals.
- **[Sealed classes]**: When you mark a type `sealed`, the compiler ensures that
switches on values of that type [exhaustively cover] every subtype. This
enables you to program in an [algebraic datatype][] style with the
compile-time safety you expect:
```dart
sealed class Amigo {}
class Lucky extends Amigo {}
class Dusty extends Amigo {}
class Ned extends Amigo {}
String lastName(Amigo amigo) =>
switch (amigo) {
Lucky _ => 'Day',
Ned _ => 'Nederlander',
};
```
In this last example, the compiler reports an error that the switch doesn't
cover the subclass `Dusty`.
- **[Class modifiers]**: New modifiers `final`, `interface`, `base`, and `mixin`
on `class` and `mixin` declarations let you control how the type can be used.
By default, Dart is flexible in that a single class declaration can be used as
an interface, a superclass, or even a mixin. This flexibility can make it
harder to evolve an API over time without breaking users. We mostly keep the
current flexible defaults, but these new modifiers give you finer-grained
control over how the type can be used.
**Breaking change:** Class declarations from libraries that have been upgraded
to Dart 3.0 can no longer be used as mixins by default. If you want the class
to be usable as both a class and a mixin, mark it [`mixin class`][mixin
class]. If you want it to be used only as a mixin, make it a `mixin`
declaration. If you haven't upgraded a class to Dart 3.0, you can still use it
as a mixin.
- **Breaking change** [#50902][]: Dart reports a compile-time error if a
`continue` statement targets a [label] that is not a loop (`for`, `do` and
`while` statements) or a `switch` member. Fix this by changing the `continue`
to target a valid labeled statement.
- **Breaking change** [language/#2357][]: Starting in language version 3.0,
Dart reports a compile-time error if a colon (`:`) is used as the
separator before the default value of an optional named parameter.
Fix this by changing the colon (`:`) to an equal sign (`=`).
[records]: https://dart.dev/language/records
[tuples]: https://en.wikipedia.org/wiki/Tuple
[pattern matching]: https://dart.dev/language/patterns
[switch cases]: https://dart.dev/language/branches#switch
[switch expressions]: https://dart.dev/language/branches#switch-expressions
[if-case statements and elements]: https://dart.dev/language/branches#if-case
[if-case element]: https://dart.dev/language/collections#control-flow-operators
[sealed classes]: https://dart.dev/language/class-modifiers#sealed
[exhaustively cover]: https://dart.dev/language/branches#exhaustiveness-checking
[algebraic datatype]: https://en.wikipedia.org/wiki/Algebraic_data_type
[class modifiers]: https://dart.dev/language/class-modifiers
[mixin class]: https://dart.dev/language/mixins#class-mixin-or-mixin-class
[#50902]: https://github.com/dart-lang/sdk/issues/50902
[label]: https://dart.dev/language/branches#switch
[language/#2357]: https://github.com/dart-lang/language/issues/2357
### Libraries
#### General changes
- **Breaking Change**: Non-`mixin` classes in the platform libraries
can no longer be mixed in, unless they are explicitly marked as `mixin class`.
The following existing classes have been made mixin classes:
* `Iterable`
* `IterableMixin` (now alias for `Iterable`)
* `IterableBase` (now alias for `Iterable`)
* `ListMixin`
* `SetMixin`
* `MapMixin`
* `LinkedListEntry`
* `StringConversionSink`
#### `dart:core`
- Added `bool.parse` and `bool.tryParse` static methods.
- Added `DateTime.timestamp()` constructor to get current time as UTC.
- The type of `RegExpMatch.pattern` is now `RegExp`, not just `Pattern`.
- **Breaking change** [#49529][]:
- Removed the deprecated `List` constructor, as it wasn't null safe.
Use list literals (e.g. `[]` for an empty list or `<int>[]` for an empty
typed list) or [`List.filled`][].
- Removed the deprecated `onError` argument on [`int.parse`][], [`double.parse`][],
and [`num.parse`][]. Use the [`tryParse`][] method instead.
- Removed the deprecated [`proxy`][] and [`Provisional`][] annotations.
The original `proxy` annotation has no effect in Dart 2,
and the `Provisional` type and [`provisional`][] constant
were only used internally during the Dart 2.0 development process.
- Removed the deprecated [`Deprecated.expires`][] getter.
Use [`Deprecated.message`][] instead.
- Removed the deprecated [`CastError`][] error.
Use [`TypeError`][] instead.
- Removed the deprecated [`FallThroughError`][] error. The kind of
fall-through previously throwing this error was made a compile-time
error in Dart 2.0.
- Removed the deprecated [`NullThrownError`][] error. This error is never
thrown from null safe code.
- Removed the deprecated [`AbstractClassInstantiationError`][] error. It was made
a compile-time error to call the constructor of an abstract class in Dart 2.0.
- Removed the deprecated [`CyclicInitializationError`]. Cyclic dependencies are
no longer detected at runtime in null safe code. Such code will fail in other
ways instead, possibly with a StackOverflowError.
- Removed the deprecated [`NoSuchMethodError`][] default constructor.
Use the [`NoSuchMethodError.withInvocation`][] named constructor instead.
- Removed the deprecated [`BidirectionalIterator`][] class.
Existing bidirectional iterators can still work, they just don't have
a shared supertype locking them to a specific name for moving backwards.
- **Breaking change when migrating code to Dart 3.0**:
Some changes to platform libraries only affect code when that code is migrated
to language version 3.0.
- The `Function` type can no longer be implemented, extended or mixed in.
Since Dart 2.0 writing `implements Function` has been allowed
for backwards compatibility, but it has not had any effect.
In Dart 3.0, the `Function` type is `final` and cannot be subtyped,
preventing code from mistakenly assuming it works.
- The following declarations can only be implemented, not extended:
* `Comparable`
* `Exception`
* `Iterator`
* `Pattern`
* `Match`
* `RegExp`
* `RegExpMatch`
* `StackTrace`
* `StringSink`
None of these declarations contained any implementation to inherit,
and are marked as `interface` to signify that they are only intended
as interfaces.
- The following declarations can no longer be implemented or extended:
* `MapEntry`
* `OutOfMemoryError`
* `StackOverflowError`
* `Expando`
* `WeakReference`
* `Finalizer`
The `MapEntry` value class is restricted to enable later optimizations.
The remaining classes are tightly coupled to the platform and not
intended to be subclassed or implemented.
[#49529]: https://github.com/dart-lang/sdk/issues/49529
[`List.filled`]: https://api.dart.dev/stable/2.18.6/dart-core/List/List.filled.html
[`int.parse`]: https://api.dart.dev/stable/2.18.4/dart-core/int/parse.html
[`double.parse`]: https://api.dart.dev/stable/2.18.4/dart-core/double/parse.html
[`num.parse`]: https://api.dart.dev/stable/2.18.4/dart-core/num/parse.html
[`tryParse`]: https://api.dart.dev/stable/2.18.4/dart-core/num/tryParse.html
[`Deprecated.expires`]: https://api.dart.dev/stable/2.18.4/dart-core/Deprecated/expires.html
[`Deprecated.message`]: https://api.dart.dev/stable/2.18.4/dart-core/Deprecated/message.html
[`AbstractClassInstantiationError`]: https://api.dart.dev/stable/2.17.4/dart-core/AbstractClassInstantiationError-class.html
[`CastError`]: https://api.dart.dev/stable/2.17.4/dart-core/CastError-class.html
[`FallThroughError`]: https://api.dart.dev/stable/2.17.4/dart-core/FallThroughError-class.html
[`NoSuchMethodError`]: https://api.dart.dev/stable/2.18.4/dart-core/NoSuchMethodError/NoSuchMethodError.html
[`NoSuchMethodError.withInvocation`]: https://api.dart.dev/stable/2.18.4/dart-core/NoSuchMethodError/NoSuchMethodError.withInvocation.html
[`CyclicInitializationError`]: https://api.dart.dev/dev/2.19.0-430.0.dev/dart-core/CyclicInitializationError-class.html
[`Provisional`]: https://api.dart.dev/stable/2.18.4/dart-core/Provisional-class.html
[`provisional`]: https://api.dart.dev/stable/2.18.4/dart-core/provisional-constant.html
[`proxy`]: https://api.dart.dev/stable/2.18.4/dart-core/proxy-constant.html
[`CastError`]: https://api.dart.dev/stable/2.18.3/dart-core/CastError-class.html
[`TypeError`]: https://api.dart.dev/stable/2.18.3/dart-core/TypeError-class.html
[`FallThroughError`]: https://api.dart.dev/dev/2.19.0-374.0.dev/dart-core/FallThroughError-class.html
[`NullThrownError`]: https://api.dart.dev/dev/2.19.0-430.0.dev/dart-core/NullThrownError-class.html
[`AbstractClassInstantiationError`]: https://api.dart.dev/stable/2.18.3/dart-core/AbstractClassInstantiationError-class.html
[`CyclicInitializationError`]: https://api.dart.dev/dev/2.19.0-430.0.dev/dart-core/CyclicInitializationError-class.html
[`BidirectionalIterator`]: https://api.dart.dev/dev/2.19.0-430.0.dev/dart-core/BidirectionalIterator-class.html
#### `dart:async`
- Added extension member `wait` on iterables and 2-9 tuples of futures.
- **Breaking change** [#49529][]:
- Removed the deprecated [`DeferredLibrary`][] class.
Use the [`deferred as`][] import syntax instead.
[#49529]: https://github.com/dart-lang/sdk/issues/49529
[`DeferredLibrary`]: https://api.dart.dev/stable/2.18.4/dart-async/DeferredLibrary-class.html
[`deferred as`]: https://dart.dev/language/libraries#deferred-loading
#### `dart:collection`
- Added extension members `nonNulls`, `firstOrNull`, `lastOrNull`,
`singleOrNull`, `elementAtOrNull` and `indexed` on `Iterable`s.
Also exported from `dart:core`.
- Deprecated the `HasNextIterator` class ([#50883][]).
- **Breaking change when migrating code to Dart 3.0**:
Some changes to platform libraries only affect code when it is migrated
to language version 3.0.
- The following interface can no longer be extended, only implemented:
* `Queue`
- The following implementation classes can no longer be implemented:
* `LinkedList`
* `LinkedListEntry`
- The following implementation classes can no longer be implemented
or extended:
* `HasNextIterator` (Also deprecated.)
* `HashMap`
* `LinkedHashMap`
* `HashSet`
* `LinkedHashSet`
* `DoubleLinkedQueue`
* `ListQueue`
* `SplayTreeMap`
* `SplayTreeSet`
[#50883]: https://github.com/dart-lang/sdk/issues/50883
#### `dart:developer`
- **Breaking change** [#49529][]:
- Removed the deprecated [`MAX_USER_TAGS`][] constant.
Use [`maxUserTags`][] instead.
- Callbacks passed to `registerExtension` will be run in the zone from which
they are registered.
- **Breaking change** [#50231][]:
- Removed the deprecated [`Metrics`][], [`Metric`][], [`Counter`][],
and [`Gauge`][] classes as they have been broken since Dart 2.0.
[#49529]: https://github.com/dart-lang/sdk/issues/49529
[#50231]: https://github.com/dart-lang/sdk/issues/50231
[`MAX_USER_TAGS`]: https://api.dart.dev/stable/2.19.6/dart-developer/UserTag/MAX_USER_TAGS-constant.html
[`maxUserTags`]: https://api.dart.dev/beta/2.19.0-255.2.beta/dart-developer/UserTag/maxUserTags-constant.html
[`Metrics`]: https://api.dart.dev/stable/2.18.2/dart-developer/Metrics-class.html
[`Metric`]: https://api.dart.dev/stable/2.18.2/dart-developer/Metric-class.html
[`Counter`]: https://api.dart.dev/stable/2.18.2/dart-developer/Counter-class.html
[`Gauge`]: https://api.dart.dev/stable/2.18.2/dart-developer/Gauge-class.html
#### `dart:ffi`
- The experimental `@FfiNative` annotation is now deprecated.
Usages should be replaced with the new `@Native` annotation.
#### `dart:html`
- **Breaking change**: As previously announced, the deprecated `registerElement`
and `registerElement2` methods in `Document` and `HtmlDocument` have been
removed. See [#49536](https://github.com/dart-lang/sdk/issues/49536) for
details.
#### `dart:math`
- **Breaking change when migrating code to Dart 3.0**:
Some changes to platform libraries only affect code when it is migrated
to language version 3.0.
- The `Random` interface can only be implemented, not extended.
#### `dart:io`
- Added `name` and `signalNumber` to the `ProcessSignal` class.
- Deprecate `NetworkInterface.listSupported`. Has always returned true since
Dart 2.3.
- Finalize `httpEnableTimelineLogging` parameter name transition from `enable`
to `enabled`. See [#43638][].
- Favor IPv4 connections over IPv6 when connecting sockets. See
[#50868].
- **Breaking change** [#51035][]:
- Update `NetworkProfiling` to accommodate new `String` ids
that are introduced in vm_service:11.0.0
[#43638]: https://github.com/dart-lang/sdk/issues/43638
[#50868]: https://github.com/dart-lang/sdk/issues/50868
[#51035]: https://github.com/dart-lang/sdk/issues/51035
#### `dart:js_util`
- Added several helper functions to access more JavaScript operators, like
`delete` and the `typeof` functionality.
- `jsify` is now permissive and has inverse semantics to `dartify`.
- `jsify` and `dartify` both handle types they understand natively more
efficiently.
- Signature of `callMethod` has been aligned with the other methods and
now takes `Object` instead of `String`.
### Tools
#### Observatory
- Observatory is no longer served by default and users should instead use Dart
DevTools. Users requiring specific functionality in Observatory should set
the `--serve-observatory` flag.
#### Web Dev Compiler (DDC)
- Removed deprecated command line flags `-k`, `--kernel`, and `--dart-sdk`.
- The compile time flag `--nativeNonNullAsserts`, which ensures web library APIs
are sound in their nullability, is by default set to true in sound mode. For
more information on the flag, see [NATIVE_NULL_ASSERTIONS.md][].
[NATIVE_NULL_ASSERTIONS.md]: https://github.com/dart-lang/sdk/blob/main/sdk/lib/html/doc/NATIVE_NULL_ASSERTIONS.md
#### dart2js
- The compile time flag `--native-null-assertions`, which ensures web library
APIs are sound in their nullability, is by default set to true in sound mode,
unless `-O3` or higher is passed, in which case they are not checked. For more
information on the flag, see [NATIVE_NULL_ASSERTIONS.md][].
[NATIVE_NULL_ASSERTIONS.md]: https://github.com/dart-lang/sdk/blob/main/sdk/lib/html/doc/NATIVE_NULL_ASSERTIONS.md
#### Dart2js
- Cleanup related to [#46100](https://github.com/dart-lang/sdk/issues/46100):
the internal dart2js snapshot fails unless it is called from a supported
interface, such as `dart compile js`, `flutter build`, or
`build_web_compilers`. This is not expected to be a visible change.
#### Formatter
* Format `sync*` and `async*` functions with `=>` bodies.
* Don't split after `<` in collection literals.
* Better indentation of multiline function types inside type argument lists.
* Fix bug where parameter metadata wouldn't always split when it should.
#### Analyzer
- Most static analysis "hints" are converted to be "warnings," and any
remaining hints are intended to be converted soon after the Dart 3.0 release.
This means that any (previously) hints reported by `dart analyze` are now
considered "fatal" (will result in a non-zero exit code). The previous
behavior, where such hints (now warnings) are not fatal, can be achieved by
using the `--no-fatal-warnings` flag. This behavior can also be altered, on a
code-by-code basis, by [changing the severity of rules] in an analysis
options file.
- Add static enforcement of the SDK-only `@Since` annotation. When code in a
package uses a Dart SDK element annotated with `@Since`, analyzer will report
a warning if the package's [Dart SDK constraint] allows versions of Dart
which don't include that element.
- Protects the Dart Analysis Server against extreme memory usage by limiting
the number of plugins per analysis context to 1. (issue [#50981][]).
[changing the severity of rules]: https://dart.dev/tools/analysis#changing-the-severity-of-rules
[Dart SDK constraint]: https://dart.dev/tools/pub/pubspec#sdk-constraints
#### Linter
Updates the Linter to `1.35.0`, which includes changes that
- add new lints:
- `implicit_reopen`
- `unnecessary_breaks`
- `type_literal_in_constant_pattern`
- `invalid_case_patterns`
- update existing lints to support patterns and class modifiers
- remove support for:
- `enable_null_safety`
- `invariant_booleans`
- `prefer_bool_in_asserts`
- `prefer_equal_for_default_values`
- `super_goes_last`
- fix `unnecessary_parenthesis` false-positives with null-aware expressions.
- fix `void_checks` to allow assignments of `Future<dynamic>?` to parameters
typed `FutureOr<void>?`.
- fix `use_build_context_synchronously` in if conditions.
- fix a false positive for `avoid_private_typedef_functions` with generalized
type aliases.
- update `unnecessary_parenthesis` to detect some doubled parens.
- update `void_checks` to allow returning `Never` as void.
- update `no_adjacent_strings_in_list` to support set literals and for- and
if-elements.
- update `avoid_types_as_parameter_names` to handle type variables.
- update `avoid_positional_boolean_parameters` to handle typedefs.
- update `avoid_redundant_argument_values` to check parameters of redirecting
constructors.
- improve performance for `prefer_const_literals_to_create_immutables`.
- update `use_build_context_synchronously` to check context properties.
- improve `unnecessary_parenthesis` support for property accesses and method
invocations.
- update `unnecessary_parenthesis` to allow parentheses in more null-aware
cascade contexts.
- update `unreachable_from_main` to track static elements.
- update `unnecessary_null_checks` to not report on arguments passed to
`Future.value` or `Completer.complete`.
- mark `always_use_package_imports` and `prefer_relative_imports` as
incompatible rules.
- update `only_throw_errors` to not report on `Never`-typed expressions.
- update `unnecessary_lambdas` to not report with `late final` variables.
- update `avoid_function_literals_in_foreach_calls` to not report with nullable-
typed targets.
- add new lint: `deprecated_member_use_from_same_package` which replaces the
soft-deprecated analyzer hint of the same name.
- update `public_member_api_docs` to not require docs on enum constructors.
- update `prefer_void_to_null` to not report on as-expressions.
#### Migration tool removal
The null safety migration tool (`dart migrate`) has been removed. If you still
have code which needs to be migrated to null safety, please run `dart migrate`
using Dart version 2.19, before upgrading to Dart version 3.0.
#### Pub
- To preserve compatibility with null-safe code pre Dart 3, Pub will interpret a
language constraint indicating a language version of `2.12` or higher and an
upper bound of `<3.0.0` as `<4.0.0`.
For example `>=2.19.2 <3.0.0` will be interpreted as `>=2.19.2 <4.0.0`.
- `dart pub publish` will no longer warn about `dependency_overrides`. Dependency
overrides only take effect in the root package of a resolution.
- `dart pub token add` now verifies that the given token is valid for including
in a header according to [RFC 6750 section
2.1](https://www.rfc-editor.org/rfc/rfc6750#section-2.1). This means they must
contain only the characters: `^[a-zA-Z0-9._~+/=-]+$`. Before a failure would
happen when attempting to send the authorization header.
- `dart pub get` and related commands will now by default also update the
dependencies in the `example` folder (if it exists). Use `--no-example` to
avoid this.
- On Windows the `PUB_CACHE` has moved to `%LOCALAPPDATA%`, since Dart 2.8 the
`PUB_CACHE` has been created in `%LOCALAPPDATA%` when one wasn't present.
Hence, this only affects users with a `PUB_CACHE` created by Dart 2.7 or
earlier. If you have `path/to/.pub-cache/bin` in `PATH` you may need to
update your `PATH`.
## 2.19.6 - 2023-03-29
This is a patch release that:
- Fixes an `Out of Memory` exception due to a VM bug. (issue [#50537]).
[#50537]: https://github.com/dart-lang/sdk/issues/50537
## 2.19.5 - 2023-03-22
This is a patch release that:
- Fixes broken usage of `Dart_CObject_Type`. (issue [#51459]).
[#51459]: https://github.com/dart-lang/sdk/issues/51459
## 2.19.4 - 2023-03-08
This is a patch release that:
- Fixes mobile devices vm crashes caused by particular use of RegExp. (issue
[#121270][]).
[#121270]: https://github.com/flutter/flutter/issues/121270
## 2.19.3 - 2023-03-01
This is a patch release that:
- Updates DDC test and builder configuration. (issue [#51481][]).
- Protects the Dart Analysis Server against extreme memory usage by limiting
the number of plugins per analysis context to 1. (issue [#50981][]).
[#50981]: https://github.com/dart-lang/sdk/issues/50981
[#51481]: https://github.com/dart-lang/sdk/issues/51481
## 2.19.2 - 2023-02-08
This is a patch release that:
- Fixes a VM crash when mixing the use of double and float calculations in
debug/jit configuration. (issue [#50622][]).
- Fixes the compiler crashing when attempting to inline a method with lots of
optional parameters with distinct default values. (issue [#119220][]).
- Fixes the `part_of_different_library` error encountered when using `PackageBuildWorkspace`. (issue [#51087][]).
[#50622]: https://github.com/dart-lang/sdk/issues/50622
[#119220]: https://github.com/flutter/flutter/issues/119220
[#51087]: https://github.com/dart-lang/sdk/issues/51087
## 2.19.1 - 2023-02-01
This is a patch release that:
- Fixes `pub get` behaviour: In Dart 2.19.0 a `dart pub get` with a
`pubspec.lock` created by a 2.18 SDK will unlock all constraints, effectively
like a `pub upgrade` (issue [#51166][]).
- Stops rewriting SDK constraints: In Dart 3, a SDK constraint like
`>=2.12.0 <3.0.0` gets interpreted by the pub client as `>=2.12.0 <4.0.0` to
allow for backwards compatibility (issue [#51101][]).
This change was intended for Dart 3.0.0 and later, but was landed already in
2.19.0. It is now being removed in 2.19.1, as it can give confusing messages
such as:
> Because library requires SDK version >=2.19.2 <4.0.0, version solving failed.
This reinterpretation no longer happens in Dart 2.19.1.
- Fixes a VM crash caused by incorrect sharing of RegExp between isolates
(issue [#51130][]).
[#51166]: https://github.com/dart-lang/sdk/issues/51166
[#51101]: https://github.com/dart-lang/sdk/issues/51101
[#51130]: https://github.com/dart-lang/sdk/issues/51130
## 2.19.0 - 2023-01-24
### Language
- **Breaking change** [#49635][]: Flag additional code as unreachable due to
types `Null` and `Never`. Several unusual constructs that lead to unreachable
code are now recognized by flow analysis:
- Control flow after an expression of the form `e ?? other` or `e ??= other`,
where `e` has static type `Null` and `other` has static type `Never`, is
considered unreachable.
- Control flow predicated on an expression of the form `e is Never` evaluating
to `true` is considered unreachable.
- Control flow predicated on an expression of the form `e is! Never`
evaluating to `false` is considered unreachable.
- Control flow on the RHS of a null-aware access such as `e?.property...`,
`e?.property = ...` or `e?.method(...)`, where `e` has static type `Null`,
is considered unreachable (Note: this can arise in the presence of extension
methods).
Previously, these behaviors only took effect if `e` was a reference to a local
variable.
Additionally, a type test of the form `v is Never` (where `v` is a local
variable) no longer promotes `v` to type `Never`.
[#49635]: https://github.com/dart-lang/sdk/issues/49635
- **Breaking Change** [#49687][]: Don't delegate inaccessible private names to
`noSuchMethod`. If a concrete class implements an interface containing a
member with a name that's private to different library, and does not inherit
an implementation of that interface member, a invocation of that member will
result in an exception getting thrown. Previously, such attempts would result
in the call being diverted to the `noSuchMethod` method.
This change closes a loophole in Dart's privacy system, where another library
can provide a different implementation of a supposedly private member using
`noSuchMethod`, and paves the way for a future implementation of promotion for
private final fields (see [#2020][]).
[#49687]: https://github.com/dart-lang/sdk/issues/49687
[#2020]: https://github.com/dart-lang/language/issues/2020
- **Breaking Change** [#50383][]: Report a compile-time error for all cyclic
dependencies during top-level type inference.
Previously, some of these dependencies were ignored, based on an analysis
determining that they could not influence the inferred type. However, this
analysis was complex, differed slightly among tools, and had become much more
complex due to other changes (especially, enhanced flow analysis).
With this change, all tools treat these cyclic dependencies in the same way,
the analysis is well-understood, and, arguably, the code is more readable.
Breakage is mitigated by adding a declared type to one top-level declaration
per cycle which is now an error.
[#50383]: https://github.com/dart-lang/sdk/issues/50383
- Add support for **unnamed libraries**. Dart language 2.19 allows a library
directive to be written without a name (`library;`). A library directive can
be used for library-level annotations (such as `@deprecated`) and for
library-level documentation comments, and with this new feature, you don't
have to provide a unique name for each library directive. Instead, a name can
simply be omitted (see [#1073][]).
[#1073]: https://github.com/dart-lang/language/issues/1073
### Libraries
#### `dart:convert`
- **Breaking change** [#34233]: The previously deprecated API
[`DEFAULT_BUFFER_SIZE`] in `JsonUtf8Encoder` has been removed.
[#34233]: https://github.com/dart-lang/sdk/issues/34233
[`DEFAULT_BUFFER_SIZE`]: https://api.dart.dev/stable/2.17.6/dart-convert/JsonUtf8Encoder/DEFAULT_BUFFER_SIZE-constant.html
#### `dart:core`
- Deprecated `FallThroughError`. Has not been thrown since Dart 2.0
(see [#49529]).
- Added `copyWith` extension method on `DateTime` (see [#24644]).
- Deprecated `RangeError.checkValidIndex` in favor of `IndexError.check`.
- Deprecated `IndexError` constructor in favor of `IndexError.withLength`
constructor.
- Deprecated `NullThrownError` and `CyclicInitializationError`.
Neither error is thrown by null safe code.
[#49529]: https://github.com/dart-lang/sdk/issues/49529
[#24644]: https://github.com/dart-lang/sdk/issues/24644
#### `dart:developer`
- **Breaking change** [#34233]: The previously deprecated APIs `kInvalidParams`,
`kExtensionError`, `kExtensionErrorMax`, and `kExtensionErrorMin` in
[`ServiceExtensionResponse`] have been removed. They have been replaced by
`invalidParams`, `extensionError`, `extensionErrorMax`, and
`extensionErrorMin`.
- Deprecated `UserTag.MAX_USER_TAGS` in favor of `UserTag.maxUserTags`.
[#34233]: https://github.com/dart-lang/sdk/issues/34233
[`ServiceExtensionResponse`]: https://api.dart.dev/stable/2.17.6/dart-developer/ServiceExtensionResponse-class.html#constants
#### `dart:ffi`
- **Breaking change** [#49935]: The runtime type argument of `Pointer` has
changed to `Never` in preparation of completely removing the runtime type
argument. `Pointer.toString` has changed to not report any type argument.
[#49935]: https://github.com/dart-lang/sdk/issues/49935
#### `dart:html`
- Add constructor and `slice` to `SharedArrayBuffer`.
- Deprecated `registerElement` and `registerElement2` in `Document` and
`HtmlDocument`. These APIs were based on the deprecated Web Components v0.5
specification and are not supported by browsers today. These APIs are expected
to be deleted in a future release. See the related breaking change request
[#49536](https://github.com/dart-lang/sdk/issues/49536).
#### `dart:io`
- **Breaking change** [#49305](https://github.com/dart-lang/sdk/issues/49305):
Disallow negative or hexadecimal content-length headers.
- **Breaking change** [#49647](https://github.com/dart-lang/sdk/issues/49647):
`File.create` now takes new optional `exclusive` `bool` parameter, and when it
is `true` the operation will fail if target file already exists.
- **Breaking change** [#49878]: Calling `ResourceHandle.toFile()`,
`ResourceHandle.toSocket()`, `ResourceHandle.toRawSocket()` or
`ResourceHandle.toRawDatagramSocket()`, more than once now throws a
`StateError`.
The previous behavior would allow multiple Dart objects to refer to the same
file descriptor, which would produce errors when one object was closed or
garbage collected.
[#49878]: https://github.com/dart-lang/sdk/issues/49878
- Adds three new `FileSystemException` subclasses to handle common error cases:
- `PathAccessException`: The necessary access rights are not available.
- `PathExistsException`: The path being created already exists.
- `PathNotFoundException`: The path being accessed does not exist.
[#12461]: https://github.com/dart-lang/sdk/issues/12461
[#50436]: https://github.com/dart-lang/sdk/issues/50436
#### `dart:isolate`
- Add `Isolate.run` to run a function in a new isolate.
- **Breaking change**: `SendPort.send` is again applying strict checks to the
contents of the message when sending messages between isolates that are not
known to share the same code (e.g. an isolate spawned via `Isolate.spawnUri`).
These checks were accidentally relaxed in an earlier Dart version allowing
all classes from `dart:core` and `dart:collection` through. This for
example means that you can't send an instance of a `HashMap` to an isolate
spawned via `Isolate.spawnUri`. See [`SendPort.send`] documentation for
the full list of restrictions.
[`SendPort.send`]: https://api.dart.dev/stable/dart-isolate/SendPort/send.html
#### `dart:mirrors`
- **Breaking change** [#34233]: The APIs [`MirrorsUsed`] and [`Comment`] have
been removed. `MirrorsUsed` was experimental and deprecated; `Comment` was
previously used internally in dart2js. Both are no longer functional.
[#34233]: https://github.com/dart-lang/sdk/issues/34233
[`MirrorsUsed`]: https://api.dart.dev/stable/dart-mirrors/MirrorsUsed-class.html
[`Comment`]: https://api.dart.dev/stable/dart-mirrors/Comment-class.html
### Other libraries
#### `package:js`
- **Breaking changes to the preview feature `@staticInterop`**:
- Classes with this annotation are now disallowed from using `external`
generative constructors. Use `external factory`s for these classes instead,
and the behavior should be identical. This includes use of synthetic
constructors. See [#48730] and [#49941] for more details.
- Classes with this annotation's external extension members are now disallowed
from using type parameters e.g. `external void method<T>(T t)`. Use a
non-`external` extension method for type parameters instead. See [#49350]
for more details.
- Classes with this annotation should also have the `@JS` annotation. You can
also have the `@anonymous` annotation with these two annotations for an
object literal constructor, but it isn't required.
- Classes with this annotation can not be implemented by classes without this
annotation. This is to avoid confusing type behavior.
[#48730]: https://github.com/dart-lang/sdk/issues/48730
[#49941]: https://github.com/dart-lang/sdk/issues/49941
[#49350]: https://github.com/dart-lang/sdk/issues/49350
### Tools
#### Analyzer
- add static enforcement of new `mustBeOverridden` annotation, and quick fixes
- add quick fixes for many diagnostics including compile-time errors, hints, and
lints. There are now quick fixes for over 300 diagnostic codes. These lint
rules have new fixes: `combinators_ordering`, `dangling_library_doc_comments`,
`implicit_call_tearoffs`, `library_annotations`, and
`unnecessary_library_directive`.
- add new hints: `body_might_complete_normally_catch_error`,
`cast_from_null_always_fails`, `cast_from_nullable_always_fails`,
`deprecated_colon_for_default_value`, and `duplicate_export`
- remove hint: `invalid_override_different_default_values`
#### Linter
Updated the Linter to `1.31.0`, which includes changes that
- add new lint: `collection_methods_unrelated_type`.
- add new lint: `combinators_ordering`.
- add new lint: `dangling_library_doc_comments`.
- add new lint: `enable_null_safety`.
- add new lint: `implicit_call_tearoffs`.
- add new lint: `library_annotations`.
- add new lint: `unnecessary_library_directive`.
- add new lint: `unreachable_from_main`.
- add new lint: `use_string_in_part_of_directives`.
- fix `no_leading_underscores_for_local_identifiers` to not report super formals
as local variables.
- fix `unnecessary_overrides` false negatives.
- fix `cancel_subscriptions` for nullable fields.
- update `library_names` to support unnamed libraries.
- fix `unnecessary_parenthesis` support for as-expressions.
- fix `use_build_context_synchronously` to check for context property accesses.
- fix false positive in `comment_references`.
- improved unrelated type checks to handle enums and cascades.
- fix `unnecessary_brace_in_string_interps` for `this` expressions .
- update `use_build_context_synchronously` for `BuildContext.mounted`.
- improve `flutter_style_todos` to handle more cases.
- fix `use_build_context_synchronously` to check for `BuildContext`s in named
expressions.
- fix `exhaustive_cases` to check parenthesized expressions
- update `avoid_redundant_argument_values` to work with enum declarations.
- fix `avoid_redundant_argument_values` when referencing required
parameters in legacy libraries.
- fix `use_super_parameters` false positives with repeated super
parameter references.
- update `use_late_for_private_fields_and_variables` to handle enums.
- fix `prefer_contains` false positives when a start index is non-zero.
- improve `noop_primitive_operations` to catch `.toString()`
in string interpolations.
- update `public_member_api_docs` to report diagnostics on extension
names (instead of bodies).
- fix `use_colored_box` and `use_decorated_box` to not over-report on containers without
a child.
- fix `unnecessary_parenthesis` false positives on a map-or-set literal at the start of
an expression statement.
- fix `prefer_final_locals` false positives reporting on fields.
- fix `unnecessary_overrides` to allow overrides on `@Protected`members.
- fix `avoid_multiple_declarations_per_line` false positives in `for` statements.
- fix `prefer_final_locals` false positives on declaration lists with at least one
non-final variable.
- fix`use_build_context_synchronously` to handle `await`s in `if` conditions.
- improves performance for:
- `avoid_escaping_inner_quotes`.
- `avoid_null_checks_in_equality_operators`.
- `avoid_positional_boolean_parameters`.
- `avoid_returning_null`.
- `avoid_returning_null`.
- `avoid_returning_this`.
- `cascade_invocations`.
- `diagnostic_describe_all_properties`.
- `flutter_style_todos`.
- `join_return_with_statement`.
- `parameter_assignments`.
- `prefer_const_constructors`.
- `prefer_constructors_over_static_methods`.
- `prefer_constructors_over_static_methods`.
- `prefer_contains`.
- `prefer_foreach`.
- `prefer_interpolation_to_compose_strings`.
- `prefer_interpolation_to_compose_strings`.
- `recursive_getters`.
- `tighten_type_of_initializing_formals`.
- `unnecessary_lambdas`.
- `use_late_for_private_fields_and_variables`.
#### Pub
- Treats packages with sdk constraint lower bound `>=2.12.0` or more and upper
bound `<3.0.0` as compatible with `<4.0.0`.
- Introduces content-hashes in pubspec.lock, to protect against corrupted
package repositories.
These will show up in the lock file on the first run of `dart pub get`.
See https://dart.dev/go/content-hashes for more details.
- New flag `dart pub get --enforce-lockfile` will fetch dependencies, but fail
if anything deviates from `pubspec.lock`. Useful for ensuring reproducible runs
in CI and production.
- Remove remaining support for `.packages` files. The flag
`--legacy-packages-file` is no longer supported.
- The client will now default to the `pub.dev` repository instead of `pub.dartlang.org`.
This will cause a change in `pubspec.lock`.
- Support a new field [`funding`](https://dart.dev/tools/pub/pubspec#funding) in `pubspec.yaml`.
- Validate the CRC32c checksum of downloaded archives and retry on failure.
- `dart pub add foo:<constraint>` with an existing dependency will now update
the constraint rather than fail.
- Update `dart pub publish` to allow `dependency_overrides` in `pubspec.yaml`.
They will still cause a publication warning.
Note that only `dependency_overrides` from the root package effect resolution.
- Update `dart pub publish` to require a working resolution.
If publishing a breaking release of mutually dependent packages use `dependency_overrides`
to obtain a resolution.
- `dart pub add` will now allow adding multiple packages from any source using
the same YAML syntax as in `pubspec.yaml`.
For example:
```console
$ dart pub add retry:^1.0.0 'dev:foo{"git":"https://github.com/foo/foo"}'
```
- `dart pub publish` will now give a warning if `dart analyze` reports any diagnostics.
- `dart pub get` now fails gracefully when run from inside the pub-cache.
- `dart pub publish` now shows the file sizes of large files in your package to
prevent accidental publication of large unrelated files.
- Fix a bug in `dart pub upgrade --major-versions` where packages not requiring
major updates would be held back unless needed.
#### dart2js
- **Breaking change** [49473](https://github.com/dart-lang/sdk/issues/49473):
dart2js no longer supports HTTP URIs as inputs.
## 2.18.5 - 2022-11-23
- fixes an error on private variable setters in mixins on dart web
(issue [#50119][]).
- fixes the handling of type parameter nullability in factory constructors
(issue [#50392][]).
[#50119]: https://github.com/dart-lang/sdk/issues/50119
[#50392]: https://github.com/dart-lang/sdk/issues/50392
## 2.18.4 - 2022-11-02
This is a patch release that fixes crashes during hot reload
(issue [flutter/flutter#113540][]).
[flutter/flutter#113540]: https://github.com/flutter/flutter/issues/113540
## 2.18.3 - 2022-10-19
This is a patch release that fixes a regression in code coverage computation
(issue [#49887][]).
[#49887]: https://github.com/dart-lang/sdk/issues/49887
## 2.18.2 - 2022-09-28
This is a patch release that:
- fixes incorrect behavior in `Uri.parse`.
- fixes a compiler crash (issue [#50052][]).
### Libraries
#### `dart:core`
- **Security advisory** [CVE-2022-3095](https://github.com/dart-lang/sdk/security/advisories/GHSA-m9pm-2598-57rj):
There is a auth bypass vulnerability in Dart SDK, specifically `dart:uri` core
library, used to parse and validate URLs. This library is vulnerable to the
backslash-trick wherein backslash is not recognized as equivalent to forward
slash in URLs.
The `Uri` class has been changed to parse a backslash in the path or the
authority separator of a URI as a forward slash. This affects the `Uri`
constructor's `path` parameter, and the `Uri.parse` method.
This change was made to not diverge as much from the browser `URL` behavior.
The Dart `Uri` class is still not an implementation of the same standard
as the browser's `URL` implementation.
[#50052]: https://github.com/dart-lang/sdk/issues/50052
## 2.18.1 - 2022-09-14
This is a patch release that fixes a crash caused by incorrect type inference
(issues [flutter/flutter#110715][] and [flutter/flutter#111088][]).
[flutter/flutter#110715]: https://github.com/flutter/flutter/issues/110715
[flutter/flutter#111088]: https://github.com/flutter/flutter/issues/111088
## 2.18.0 - 2022-08-30
### Language
The following features are new in the Dart 2.18 [language version][]. To use
them, you must set the lower bound on the SDK constraint for your package to
2.18 or greater (`sdk: '>=2.18.0 <3.0.0'`).
[language version]: https://dart.dev/guides/language/evolution
- **[Enhanced type inference for generic invocations with function literals][]**:
Invocations of generic methods/constructors that supply function literal
arguments now have improved type inference. This primarily affects the
`Iterable.fold` method. For example, in previous versions of Dart, the
compiler would fail to infer an appropriate type for the parameter `a`:
```dart
void main() {
List<int> ints = [1, 2, 3];
var maximum = ints.fold(0, (a, b) => a < b ? b : a);
}
```
With this improvement, `a` receives its type from the initial value, `0`.
On rare occasions, the wrong type will be inferred, leading to a compile-time
error, for example in this code, type inference will infer that `a` has a
type of `Null`:
```dart
void main() {
List<int> ints = [1, 2, 3];
var maximumOrNull = ints.fold(null,
(a, b) => a == null || a < b ? b : a);
}
```
This can be worked around by supplying the appropriate type as an explicit
type argument to `fold`:
```dart
void main() {
List<int> ints = [1, 2, 3];
var maximumOrNull = ints.fold<int?>(null,
(a, b) => a == null || a < b ? b : a);
}
```
[Enhanced type inference for generic invocations with function literals]: https://github.com/dart-lang/language/issues/731
- **Breaking Change** [#48167](https://github.com/dart-lang/sdk/issues/48167):
Mixin of classes that don't extend `Object` is no longer supported:
```dart
class Base {}
class Mixin extends Base {}
class C extends Base with Mixin {}
```
This should instead be written using a mixin declaration of `Mixin`:
```dart
class Base {}
mixin Mixin on Base {}
class C extends Base with Mixin {}
```
This feature has not been supported in most compilation targets for some
time but is now completely removed.
### Core libraries
#### `dart:async`
- The `Stream.fromIterable` stream can now be listened to more than once.
#### `dart:collection`
- Deprecates `BidirectionalIterator`.
#### `dart:core`
- Allow omitting the `unencodedPath` positional argument to `Uri.http` and
`Uri.https` to default to an empty path.
#### `dart:html`
- Add `connectionState` attribute and `connectionstatechange` listener to
`RtcPeerConnection`.
#### `dart:io`
- **Breaking Change** [#49045](https://github.com/dart-lang/sdk/issues/49045):
The `uri` property of `RedirectException` in `dart:io` has been changed to
be nullable. Programs must be updated to handle the `null` case.
- **Breaking Change** [#34218](https://github.com/dart-lang/sdk/issues/34218):
Constants in `dart:io`'s networking APIs following the `SCREAMING_CAPS`
convention have been removed (they were previously deprecated). Please use
the corresponding `lowerCamelCase` constants instead.
- **Breaking Change** [#45630][]: The Dart VM no longer automatically restores
the initial terminal settings upon exit. Programs that change the `Stdin`
settings `lineMode` and `echoMode` are now responsible for restoring the
settings upon program exit. E.g. a program disabling `echoMode` will now
need to restore the setting itself and handle exiting by the appropriate
signals if desired:
```dart
import 'dart:io';
import 'dart:async';
main() {
bool echoWasEnabled = stdin.echoMode;
try {
late StreamSubscription subscription;
subscription = ProcessSignal.sigint.watch().listen((ProcessSignal signal) {
stdin.echoMode = echoWasEnabled;
subscription.cancel();
Process.killPid(pid, signal); /* Die by the signal. */
});
stdin.echoMode = false;
} finally {
stdin.echoMode = echoWasEnabled;
}
}
```
This change is needed to fix [#36453][] where the dart programs not caring
about the terminal settings can inadvertently corrupt the terminal settings
when e.g. piping into less.
Furthermore the `echoMode` setting now only controls the `echo` local mode
and no longer sets the `echonl` local mode on POSIX systems (which controls
whether newline are echoed even if the regular echo mode is disabled). The
`echonl` local mode is usually turned off in common shell environments.
Programs that wish to control the `echonl` local mode can use the new
`echoNewlineMode` setting.
The Windows console code pages (if not UTF-8) and ANSI escape code support
(if disabled) remain restored when the VM exits.
[#45630]: https://github.com/dart-lang/sdk/issues/45630
[#36453]: https://github.com/dart-lang/sdk/issues/36453
#### `dart:js_util`
- Added `dartify` and a number of minor helper functions.
### Dart VM
Implementation of `async`/`async*`/`sync*` is revamped in Dart VM,
both in JIT and AOT modes. This also affects Flutter except Flutter Web.
Besides smaller code size and better performance of async methods,
the new implementation carries a few subtle changes in behavior:
- If `async` method returns before reaching the first `await`, it now
returns a completed Future.
Previously `async` methods completed resulting Future in separate microtasks.
- Stack traces no longer have duplicate entries for `async` methods.
- New implementation now correctly throws an error if `null` occurs as
an argument of a logical expression (`&&` and `||`) which also contains
an `await`.
- New implementation avoids unnecessary extending the liveness of local
variables in `async`/`async*`/`sync*` methods, which means that unused
objects stored in local variables in such methods might be garbage
collected earlier than they were before
(see issue [#36983](https://github.com/dart-lang/sdk/issues/36983)
for details).
### Tools
#### General
- **Breaking Change** [#48272](https://github.com/dart-lang/sdk/issues/48272):
The `.packages` file has been fully discontinued. Historically when the
commands `dart pub get` or `flutter pub get` are executed, pub resolved all
dependencies, and installs those dependencies to the local pub cache. It
furthermore created a mapping from each used package to their location on the
local file system, and wrote that into two files:
* `.dart_tool/package_config.json`
* `.packages` (deprecated in Dart 2.8.0)
As of Dart 2.18.0, the `.packages` is now fully desupported, and all tools
distributed in, and based on, the Dart SDK no longer support it, and thus
solely use the `.dart_tool/package_config.json` file. If you've run `dart pub
get` or `flutter pub get` with any Dart SDK from the past few years you
already have a `.dart_tool/package_config.json` and thus should not be
impacted. You can delete any old `.packages` files.
If you have any third-party tools that for historical reasons depend on a
`.packages` we will support the ability to generate a `.packages` by passing
the flag `--legacy-packages-file` to `dart pub get`. This support will be
removed in a following stable release.
#### Dart command line
- **Breaking change** [#46100](https://github.com/dart-lang/sdk/issues/46100):
The standalone `dart2js` and `dartdevc` tools have been removed as previously
announced. `dart2js` is replaced by the `dart compile js` command, `dartdevc`
is no longer exposed as a command-line tool.
- **Breaking change** [#46100](https://github.com/dart-lang/sdk/issues/46100):
The standalone `dartanalyzer` tool has been removed as previously
announced. `dartanalyzer` is replaced by the `dart analyze` command.
#### Analyzer
- added quick fixes for diagnostics: `abstract_field_constructor_initializer`,
`abstract_class_member`,
[`always_put_control_body_on_new_line`](https://dart.dev/lints/always_put_control_body_on_new_line),
[`avoid_print`](https://dart.dev/lints/avoid_print),
[`avoid_renaming_method_parameters`](https://dart.dev/lints/avoid_renaming_method_parameters),
[`discarded_futures`](https://dart.dev/lints/discarded_futures),
`enum_with_abstract_member`, `non_bool_condition`,
`super_formal_parameter_without_associated_named`,
[`unawaited_futures`](https://dart.dev/lints/unawaited_futures),
`unnecessary_final` `unused_element_parameter`,
- added new Hint: `deprecated_export_use`
#### Linter
Updated the Linter to `1.25.0`, which includes changes that
- add new lint: `discarded_futures`.
- add new lint: `unnecessary_null_aware_operator_on_extension_on_nullable`.
- add new lint: `unnecessary_to_list_in_spreads`.
- improve message and highlight range for `no_duplicate_case_values`
- improve performance for `lines_longer_than_80_chars`,
`prefer_const_constructors_in_immutables`, and
`prefer_initializing_formals`.
- fix `prefer_final_parameters` to support super parameters.
- fix `unawaited_futures` to handle string interpolated
futures.
- update `use_colored_box` to not flag nullable colors,
- fix `no_leading_underscores_for_local_identifiers`
to lint local function declarations.
- fix `avoid_init_to_null` to correctly handle super
initializing defaults that are non-null.
- update `no_leading_underscores_for_local_identifiers`
to allow identifiers with just underscores.
- fix `flutter_style_todos` to support usernames that
start with a digit.
- update `require_trailing_commas` to handle functions
in asserts and multi-line strings.
- update `unsafe_html` to allow assignments to
`img.src`.
- fix `unnecessary_null_checks` to properly handle map
literal entries.
#### Pub
* `dart pub get` and `dart pub upgrade` no longer create the
`.packages` file. For details, see breaking change #48272 above.
* `dart pub outdated` now shows which of your dependencies are discontinued.
* `dart pub publish` will now list all the files it is about to publish.
## 2.17.7 - 2022-08-24
This is a patch release that:
- fixes a crash in the debugger (issue [#49209][]).
[#49209]: https://github.com/dart-lang/sdk/issues/49209
## 2.17.6 - 2022-07-13
This is a patch release that:
- improves code completion for Flutter (issue [#49054][]).
- fixes a crash on ARM (issue [#106510][]).
- fixes a compiler crash with Finalizable parameters (issue [#49402][]).
[#49054]: https://github.com/dart-lang/sdk/issues/49054
[#106510]: https://github.com/flutter/flutter/issues/106510
[#49402]: https://github.com/dart-lang/sdk/issues/49402
## 2.17.5 - 2022-06-22
This is a patch release that:
- improves analysis of enums and switch (issue [#49188][]).
- fixes a compiler crash when initializing Finalizable objects
(issue [#49075][]).
[#49188]: https://github.com/dart-lang/sdk/issues/49188
[#49075]: https://github.com/dart-lang/sdk/issues/49075
## 2.17.3 - 2022-06-01
This is a patch release that fixes:
- a Dart VM compiler crash (issue [#100375][]).
- code completion when writing method overrides (issue [#49027][]).
- the `dart pub login` command (issue [#3424][]).
- analysis of enhanced enums (issue [#49097][]).
[#100375]: https://github.com/flutter/flutter/issues/100375
[#49027]: https://github.com/dart-lang/sdk/issues/49027
[#3424]: https://github.com/dart-lang/pub/issues/3424
[#49097]: https://github.com/dart-lang/sdk/issues/49097
## 2.17.1 - 2022-05-18
This is a patch release that fixes:
- an analyzer plugin crash (issue [#48682][]).
- Dart FFI support for `late` `Finalizable` variables (issue [#49024]).
- `dart compile` on macOS 10.15 (issue [#49010][]).
[#48682]: https://github.com/dart-lang/sdk/issues/48682
[#49024]: https://github.com/dart-lang/sdk/issues/49024
[#49010]: https://github.com/dart-lang/sdk/issues/49010
## 2.17.0 - 2022-05-11
### Language
The following features are new in the Dart 2.17 [language version][]. To use
them, you must set the lower bound on the SDK constraint for your package to
2.17 or greater (`sdk: '>=2.17.0 <3.0.0'`).
[language version]: https://dart.dev/guides/language/evolution
- **[Enhanced enums with members][]**: Enum declarations can now define
members including fields, constructors, methods, getters, etc. For example:
```dart
enum Water {
frozen(32),
lukewarm(100),
boiling(212);
final int tempInFahrenheit;
const Water(this.tempInFahrenheit);
@override
String toString() => "The $name water is $tempInFahrenheit F.";
}
```
Constructors must be `const` since enum values are always constants. If the
constructor takes arguments, they are passed when the enum value is
declared.
The above enum can be used like so:
```dart
void main() {
print(Water.frozen); // prints "The frozen water is 32 F."
}
```
[enhanced enums with members]: https://github.com/dart-lang/language/blob/master/accepted/future-releases/enhanced-enums/feature-specification.md
- **[Super parameters][]**: When extending a class whose constructor takes
parameters, the subclass constructor needs to provide arguments for them.
Often, these are passed as parameters to the subclass constructor, which
then forwards them to the superclass constructor. This is verbose because
the subclass constructor must list the name and type of each parameter in
its parameter list, and then explicitly forward each one as an argument to
the superclass constructor.
[@roy-sianez][] suggested [allowing `super.`][super dot] before a subclass
constructor parameter to implicitly forward it to the corresponding
superclass constructor parameter. Applying this feature to Flutter
eliminated [nearly 2,000 lines of code][flutter super]. For example, before:
```dart
class CupertinoPage<T> extends Page<T> {
const CupertinoPage({
required this.child,
this.maintainState = true,
this.title,
this.fullscreenDialog = false,
LocalKey? key,
String? name,
Object? arguments,
String? restorationId,
}) : super(
key: key,
name: name,
arguments: arguments,
restorationId: restorationId,
);
// ...
}
```
And using super parameters:
```dart
class CupertinoPage<T> extends Page<T> {
const CupertinoPage({
required this.child,
this.maintainState = true,
this.title,
this.fullscreenDialog = false,
super.key,
super.name,
super.arguments,
super.restorationId,
});
// ...
}
```
From our analysis, over 90% of explicit superclass constructor calls can be
completely eliminated, using `super.` parameters instead.
[super parameters]: https://github.com/dart-lang/language/blob/master/working/1855%20-%20super%20parameters/proposal.md
[@roy-sianez]: https://github.com/roy-sianez
[super dot]: https://github.com/dart-lang/language/issues/1855
[flutter super]: https://github.com/flutter/flutter/pull/100905/files
- **[Named args everywhere][]**: In a function call, Dart requires positional
arguments to appear before named arguments. This can be frustrating for
arguments like collection literals and function expressions that look best
as the last argument in the argument list but are positional, like the
`test()` function in the [test package][]:
```dart
main() {
test('A test description', () {
// Very long function body here...
}, skip: true);
}
```
It would be better if the `skip` argument appeared at the top of the call
to `test()` so that it wasn't easily overlooked, but since it's named and
the test body argument is positional, `skip` must be placed at the end.
Dart 2.17 removes this restriction. Named arguments can be freely
interleaved with positional arguments, allowing code like:
```dart
main() {
test(skip: true, 'A test description', () {
// Very long function body here...
});
}
```
[named args everywhere]: https://github.com/dart-lang/language/blob/master/accepted/future-releases/named-arguments-anywhere/feature-specification.md
[test package]: https://pub.dev/packages/test
### Core libraries
#### `dart:core`
- Add `Finalizer` and `WeakReference` which can potentially detect when
objects are "garbage collected".
- Add `isMimeType` method to `UriData` class, to allow case-insensitive
checking of the MIME type.
- Add `isCharset` and `isEncoding` methods to `UriData` class,
to allow case-insensitive and alternative-encoding-name aware checking
of the MIME type "charset" parameter.
- Make `UriData.fromString` and `UriData.fromBytes` recognize and omit
a "text/plain" `mimeType` even if it is not all lower-case.
#### `dart:ffi`
- Add `ref=` and `[]=` methods to the `StructPointer` and `UnionPointer`
extensions. They copy a compound instance into a native memory region.
- Add `AbiSpecificInteger`s for common C types:
- `char`
- `unsigned char`
- `signed char`
- `short`
- `unsigned short`
- `int`
- `unsigned int`
- `long`
- `unsigned long`
- `long long`
- `unsigned long long`
- `uintptr_t`
- `size_t`
- `wchar_t`
- Add `NativeFinalizer` which can potentially detect when objects are
"garbage collected". `NativeFinalizer`s run native code where `dart:core`'s
`Finalizer`s run Dart code on finalization.
#### `dart:html`
- Add `scrollIntoViewIfNeeded` to `Element`. Previously, this method was nested
within `scrollIntoView` based on the `ScrollAlignment` value. `scrollIntoView`
is unchanged for now, but users who intend to use the native
`Element.scrollIntoViewIfNeeded` should use the new `scrollIntoViewIfNeeded`
definition instead.
- Change `Performance.mark` and `Performance.measure` to accept their different
overloads. `mark` can now accept a `markOptions` map, and `measure` can now
accept a `startMark` and `endMark`, or a `measureOptions` map. Both methods
return their correct return types now as well - `PerformanceEntry?` and
`PerformanceMeasure?`, respectively.
#### `dart:indexed_db`
- `IdbFactory.supportsDatabaseNames` has been deprecated. It will always return
`false`.
#### `dart:io`
- **Breaking Change** [#47887](https://github.com/dart-lang/sdk/issues/47887):
`HttpClient` has a new `connectionFactory` property, which allows socket
creation to be customized. Classes that `implement HttpClient` may be broken
by this change. Add the following method to your classes to fix them:
```dart
void set connectionFactory(
Future<ConnectionTask<Socket>> Function(
Uri url, String? proxyHost, int? proxyPort)?
f) =>
throw UnsupportedError("connectionFactory not implemented");
```
- **Breaking Change** [#48093](https://github.com/dart-lang/sdk/issues/48093):
`HttpClient` has a new `keyLog` property, which allows TLS keys to be logged
for debugging purposes. Classes that `implement HttpClient` may be broken by
this change. Add the following method to your classes to fix them:
```dart
void set keyLog(Function(String line)? callback) =>
throw UnsupportedError("keyLog not implemented");
```
- **Breaking Change** [#34218](https://github.com/dart-lang/sdk/issues/34218):
Constants in `dart:io` following the `SCREAMING_CAPS` convention have been
removed (they were previously deprecated). Please use the corresponding
`lowerCamelCase` constants instead.
- **Breaking Change** [#48513](https://github.com/dart-lang/sdk/issues/48513):
Add a new `allowLegacyUnsafeRenegotiation` property to `SecurityContext`,
which allows TLS renegotiation for client secure sockets.
- Add a optional `keyLog` parameter to `SecureSocket.connect` and
`SecureSocket.startConnect`.
- Deprecate `SecureSocket.renegotiate` and `RawSecureSocket.renegotiate`,
which were no-ops.
### Tools
#### Dart command line
- **Breaking change** [#46100](https://github.com/dart-lang/sdk/issues/46100):
The standalone `dart2js` tool has been
marked deprecated as previously announced.
Its replacement is the `dart compile js` command.
Should you find any issues, or missing features, in the replacement
command, kindly file [an issue](https://github.com/dart-lang/sdk/issues/new).
- **Breaking change** [#46100](https://github.com/dart-lang/sdk/issues/46100):
The standalone `dartdevc` tool has been marked deprecated as previously
announced and will be deleted in a future Dart stable release. This tool
was intended for use only by build systems like bazel, `build_web_compilers`
and `flutter_tools`. The functionality remains available for those systems,
but it is no longer exposed as a command-line tool in the SDK.
Please share any concerns in the
[breaking change tracking issue](https://github.com/dart-lang/sdk/issues/46100).
- **Breaking change** [#46100](https://github.com/dart-lang/sdk/issues/46100):
The standalone `dartdoc` tool has been removed as
previously announced. Its replacement is the `dart doc` command.
- The template names used in the `dart create` command have been simplified,
and the current template names are now the set shown below. (Note: for
backwards compatibility the former template names can still be used.)
```
[console] (default) A command-line application.
[package] A package containing shared Dart libraries.
[server-shelf] A server app using package:shelf.
[web] A web app that uses only core Dart libraries.
```
#### Analyzer
- added quick fixes for diagnostics:
[`always_use_package_imports`](https://dart.dev/lints/always_use_package_imports),
[`avoid_void_async`](https://dart.dev/lints/avoid_void_async),
[`cascade_invocations`](https://dart.dev/lints/cascade_invocations),
`default_list_constructor`,
[`must_call_super`](https://dart.dev/tools/diagnostic-messages#must_call_super),
[`no_leading_underscores_for_local_identifiers`](https://dart.dev/lints/no_leading_underscores_for_local_identifiers),
[`null_check_on_nullable_type_parameter`](https://dart.dev/lints/null_check_on_nullable_type_parameter),
[`prefer_function_declarations_over_variables`](https://dart.dev/lints/prefer_function_declarations_over_variables),
[`sort_constructors_first`](https://dart.dev/lints/sort_constructors_first),
[`sort_unnamed_constructors_first`](https://dart.dev/lints/sort_unnamed_constructors_first),
`undefined_enum_constant`,
[`unnecessary_late`](https://dart.dev/lints/unnecessary_late),
`unnecessary_null_aware_assignments`,
[`use_enums`](https://dart.dev/lints/use_enums),
[`use_raw_strings`](https://dart.dev/lints/use_raw_strings),
[`use_super_parameters`](https://dart.dev/lints/use_super_parameters),
`var_return_type`
- added many errors for invalid enhanced enums
- added new Hint: [`unnecessary_final`](https://dart.dev/tools/diagnostic-messages#unnecessary_final)
- added new FFI error: `compound_implements_finalizable`
- improved errors for invalid Unicode escapes in source code
#### Linter
Updated the Linter to `1.22.0`, which includes changes that
- fixes null-safe variance exceptions in `invariant_booleans`.
- updates `depend_on_referenced_packages` to treat `flutter_gen` as a virtual
package, not needing an explicit dependency.
- updates `unnecessary_null_checks` and
`null_check_on_nullable_type_parameter` to handle
list/set/map literals, and `yield` and `await` expressions.
- fixes `unnecessary_null_aware_assignments` property-access
false positives.
- adds new lint: `use_super_parameters`.
- adds new lint: `use_enums`.
- adds new lint: `use_colored_box`.
- improves performance for `sort_constructors`.
- improves docs for `always_use_package_imports`,
`avoid_print`, and `avoid_relative_lib_imports` .
- updates `avoid_void_async` to skip `main` functions.
- updates `prefer_final_parameters` to not super on super params.
- updates lints for enhanced-enums and super-initializer language
features.
- updates `unnecessary_late` to report on variable names.
- marks `null_check_on_nullable_type_parameter` stable.
#### Dartdoc
Updated dartdoc to 5.1.0, which includes changes that
- support the enhanced enums feature
- remove superfluous `[...]` links
- fix `categoryOrder` option
- display categorized extensions
- add annotations to extensions
- make minor improvements to performance
## 2.16.2 - 2022-03-24
This is a patch release that fixes a dart2js crash when building some Flutter
web apps (issue [#47916][]).
[#47916]: https://github.com/dart-lang/sdk/issues/47916
## 2.16.1 - 2022-02-09
This is a patch release that fixes an AOT precompiler crash when building some
Flutter apps (issue [flutter/flutter#97301][]).
[flutter/flutter#97301]: https://github.com/flutter/flutter/issues/97301
## 2.16.0 - 2022-02-03
### Core libraries
#### `dart:core`
- Add `Error.throwWithStackTrace` which can `throw` an
error with an existing stack trace, instead of creating
a new stack trace.
#### `dart:ffi`
- Add `Abi` and `AbiSpecificInteger`. These enable specifying integers which
have different sizes/signs per ABI (hardware and OS combination).
#### `dart:io`
- **Security advisory**
[CVE-2022-0451](https://github.com/dart-lang/sdk/security/advisories/GHSA-c8mh-jj22-xg5h),
**breaking change** [#45410](https://github.com/dart-lang/sdk/issues/45410):
`HttpClient` no longer transmits some headers (i.e. `authorization`,
`www-authenticate`, `cookie`, `cookie2`) when processing redirects to a
different domain.
- **Breaking change** [#47653](https://github.com/dart-lang/sdk/issues/47653):
On Windows, `Directory.rename` will no longer delete a directory if
`newPath` specifies one. Instead, a `FileSystemException` will be thrown.
- **Breaking change** [#47769](https://github.com/dart-lang/sdk/issues/47769):
The `Platform.packageRoot` API has been removed. It had been marked deprecated
in 2018, as it doesn't work with any Dart 2.x release.
- Add optional `sourcePort` parameter to `Socket.connect`, `Socket.startConnect`, `RawSocket.connect` and `RawSocket.startConnect`
#### `dart:isolate`
- **Breaking change** [#47769](https://github.com/dart-lang/sdk/issues/47769):
The `Isolate.packageRoot` API has been removed. It had been marked deprecated
in 2018, as it doesn't work with any Dart 2.x release.
### Tools
#### Dart command line
- **Breaking change** [#46100](https://github.com/dart-lang/sdk/issues/46100):
The standalone `dartanalyzer` tool has been
marked deprecated as previously announced.
Its replacement is the `dart analyze` command.
Should you find any issues, or missing features, in the replacement
command, kindly file [an issue][].
[an issue]: https://github.com/dart-lang/sdk/issues/new
- **Breaking change** [#46100](https://github.com/dart-lang/sdk/issues/46100):
The standalone `dartdoc` tool has been
marked deprecated as previously announced.
Its replacement is the `dart doc` command.
Should you find any issues, or missing features, in the replacement
command, kindly file [an issue][].
[an issue]: https://github.com/dart-lang/sdk/issues/new
- **Breaking Change** [#46100](https://github.com/dart-lang/sdk/issues/46100):
The deprecated standalone `pub` tool has been removed.
Its replacement is the `dart pub` command.
Should you find any issues, or missing features, in the replacement
command, kindly file [an issue][].
[an issue]: https://github.com/dart-lang/pub/issues/new
#### Pub
- Fixed race conditions in `dart pub get`, `dart run` and `dart pub global run`.
It should now be safe to run these concurrently.
- If (when) Pub crashes it will save a verbose log in
`$PUB_CACHE/log/pub_log.txt` This can be used for filing issues to the issue
tracker.
`dart --verbose pub [command]` will also cause the log file to be written.
- `dart pub global activate --source=git` now takes arguments `--git-path` to
specify the path of the activated package in the pubspec and `--git-ref` to
specify the branch or revision to check out.
- `dart pub add` can now add multiple packages in one command.
- `dart pub token add` can now add a token for [pub.dev](https://pub.dev).
- `dart pub uploader` has been removed. To manage uploaders for a package use
the `https://pub.dev/<packagename>/admin` web-interface.
- Pub now supports a separate `pubspec_overrides.yaml` file that can contain
`dependency_overrides`. This makes it easier to avoid checking the local
overrides into version control.
#### Linter
Updated the Linter to `1.18.0`, which includes changes that
- extends `camel_case_types` to cover enums.
- fixes `no_leading_underscores_for_local_identifiers` to not
mis-flag field formal parameters with default values.
- fixes `prefer_function_declarations_over_variables` to not
mis-flag non-final fields.
- improves performance for `prefer_contains`.
- updates `exhaustive_cases` to skip deprecated values that
redirect to other values.
- adds new lint: `unnecessary_late`.
- improves docs for `prefer_initializing_formals`.
- updates `secure_pubspec_urls` to check `issue_tracker` and
`repository` entries.
- adds new lint: `conditional_uri_does_not_exist`.
- improves performance for
`missing_whitespace_between_adjacent_strings`.
- adds new lint: `avoid_final_parameters`.
- adds new lint: `no_leading_underscores_for_library_prefixes`.
- adds new lint: `no_leading_underscores_for_local_identifiers`.
- adds new lint: `secure_pubspec_urls`.
- adds new lint: `sized_box_shrink_expand`.
- adds new lint: `use_decorated_box`.
- improves docs for `omit_local_variable_types`.
## 2.15.1 - 2021-12-14
This is a patch release that fixes:
- an AOT compilation failure in some Flutter apps (issue [#47878][]).
- `dart pub publish` for servers with a path in the URL (pr
[dart-lang/pub#3244][]).
[#47878]: https://github.com/dart-lang/sdk/issues/47878
[dart-lang/pub#3244]: https://github.com/dart-lang/pub/pull/3244
## 2.15.0 - 2021-12-08
- **Security advisory**
[CVE-2021-22567](https://github.com/dart-lang/sdk/security/advisories/GHSA-8pcp-6qc9-rqmv):
Bidirectional Unicode text can be interpreted and compiled differently than
how it appears in editors and code-review tools. Exploiting this an attacker
could embed source that is invisible to a code reviewer but that modifies the
behavior of a program in unexpected ways. Dart 2.15.0 introduces new analysis
warnings that flags the use of these.
- **Security advisory**
[CVE-2021-22568](https://github.com/dart-lang/sdk/security/advisories/GHSA-r32f-vhjp-qhj7):
A malicious third-party package repository may impersonate a user on pub.dev
for up to one hour after the user has published a package to that third-party
package repository using `dart pub publish`. As of Dart SDK version 2.15.0
requests to third-party package repositories will no longer include an OAuth2
`access_token` intended for pub.dev.
### Language
The following features are new in the Dart 2.15 [language version][]. To use
them, you must set the lower bound on the SDK constraint for your package to
2.15 or greater (`sdk: '>=2.15.0 <3.0.0'`).
[language version]: https://dart.dev/guides/language/evolution
- **[Constructor tear-offs][]**: Previous Dart versions allowed a method on an
instance to be passed as a closure, and similarly for static methods. This is
commonly referred to as "closurizing" or "tearing off" a method. Constructors
were not previously eligible for closurization, forcing users to explicitly
write wrapper functions when using constructors as first class functions.
See the calls to `map()` in this example:
```dart
class A {
int x;
A(this.x);
A.fromString(String s) : x = int.parse(s);
}
void main() {
var listOfInts = [1, 2, 3];
var listOfStrings = ["1", "2", "3"];
for(var a in listOfInts.map((x) => A(x))) {
print(a.x);
}
for(var a in listOfStrings.map((x) => A.fromString(x))) {
print(a.x);
}
}
```
New in Dart 2.15, constructors are now allowed to be torn off. Named
constructors are closurized using their declared name (here `A.fromString`).
To closurize unnamed constructors, use the keyword `new` (here `A.new`).
The above example may now be written as:
```dart
class A {
int x;
A(this.x);
A.fromString(String s) : x = int.parse(s);
}
void main() {
var listOfInts = [1, 2, 3];
var listOfStrings = ["1", "2", "3"];
for(A a in listOfInts.map(A.new)) {
print(a.x);
}
for(A a in listOfStrings.map(A.fromString)) {
print(a.x);
}
}
```
Constructors for generic classes may be torn off as generic functions, or
instantiated at the tear-off site. In the following example, the tear-off
`G.new` is used to initialize the variable `f` produces a generic function
which may be used to produce an instance of `G<T>` for any type `T` provided
when `f` is called. The tear-off `G<String>.new` is used to initialize the
variable `g` to produce a non-generic function which may only be used
to produce instances of type `G<String>`.
```dart
class G<T> {
T x;
G(this.x);
}
void main() {
G<T> Function<T>(T x) f = G.new;
var x = f<int>(3);
G<String> Function(String y) g = G<String>.new;
var y = g("hello");
}
```
[constructor tear-offs]: https://github.com/dart-lang/language/blob/master/accepted/2.15/constructor-tearoffs/feature-specification.md
- **[Generic type literals][explicit instantiation]**: Previous Dart versions
allowed class names to be used as type literals. So for example,`int` may be
used as an expression, producing a value of type `Type`. Generic classes (e.g.
`List`) could be referred to by name as an expression, but no type arguments
could be provided and so only the `dynamic` instantiation could be produced
directly as an expression without using indirect methods:
```dart
// Workaround to capture generic type literals.
Type typeOf<T>() => T;
void main() {
var x = int; // The Type literal corresponding to `int`.
var y = List; // The Type literal corresponding to `List<dynamic>`.
// Use workaround to capture generic type literal.
var z = typeOf<List<int>>(); // The Type literal for `List<int>`.
}
```
New in Dart 2.15, instantiations of generic classes may now be used as Type
literals:
```dart
void main() {
var x = int; // The Type literal corresponding to `int`.
var y = List; // The Type literal corresponding to `List<dynamic>`.
var z = List<int>; // The Type literal corresponding to `List<int>`.
}
```
- **[Explicit generic method instantiations][explicit instantiation]**: Previous
Dart versions allowed generic methods to be implicitly specialized (or
"instantiated") to non-generic versions when assigned to a location with a
compatible monomorphic type. Example:
```dart
// The generic identity function.
T id<T>(T x) => x;
void main() {
// Initialize `intId` with a version of `id` implicitly specialized to
// `int`.
int Function(int) intId = id;
print(intId(3));
// Initialize `stringId` with a version of `id` implicitly specialized to
// `String`.
String Function(String) stringId = id;
print(stringId("hello"));
}
```
New in Dart 2.15, generic methods may be explicitly instantiated using the
syntax `f<T>` where `f` is the generic method to specialize and `T` is the
type argument (in general, type arguments) to be used to specialize the
method. Example:
```dart
// The generic identity function.
T id<T>(T x) => x;
void main() {
// Initialize `intId` with a version of `id` explicitly specialized to
// `int`.
var intId = id<int>;
print(intId(3));
// Initialize `stringId` with a version of `id` explicitly specialized to
// `String`.
var stringId = id<String>;
print(stringId("hello"));
}
```
[explicit instantiation]: https://github.com/dart-lang/language/blob/master/accepted/2.15/constructor-tearoffs/feature-specification.md#explicitly-instantiated-classes-and-functions
- **[Generic instantiation of function objects][object instantiation]**: Generic
function instantiation was previously restricted to function declarations. For
example, as soon as a function had been torn off, it could not be
instantiated:
```dart
// Before Dart 2.15:
X id<X>(X x) => x;
void main() {
var fo = id; // Tear off `id`, creating a function object.
var c1 = fo<int>; // Compile-time error: can't instantiate `fo`.
int Function(int) c2 = fo; // Same compile-time error.
// Constants are treated the same.
}
```
New in Dart 2.15, this restriction has been lifted. It is now possible
to obtain a generic instantiation of an existing function object, both
explicitly and implicitly (again, this works the same for non-constants):
```dart
X id<X>(X x) => x;
X other<X>(X x) => throw x;
void main() {
const fo = id; // Tear off `id`, creating a function object.
// Generic function instantiation on `fo` is no longer an error.
const c1 = fo<int>; // OK.
const int Function(int) c2 = fo; // OK.
// This also generalizes function instantiation because we can,
// e.g., use non-trivial expressions and go via a constructor.
const c3 = A(true); // OK.
}
class A {
final int Function(int) x;
// `(...)<T>` is now allowed, also in a `const` constructor.
const A(bool b): x = (b ? id : other)<int>;
}
```
[Object instantiation]: https://github.com/dart-lang/language/pull/1812
- Annotations on type parameters of classes can no longer refer to class members
without a prefix. For example, this used to be permitted:
```dart
class C<@Annotation(foo) T> {
static void foo() {}
}
```
Now, the reference must be qualified with the class name, i.e.:
```dart
class C<@Annotation(C.foo) T> {
static void foo() {}
}
```
This brings the implementation behavior in line with the spec.
- Initializer expressions on implicitly typed condition variables can now
contribute to type promotion. For example, this program no longer produces a
compile-time error:
```dart
f(int? i) {
var iIsNull = i == null;
if (!iIsNull) {
print(i + 1); // OK, because `i` is known to be non-null.
}
}
```
Previously, the above program had a compile-time error due to a bug
([#1785][]) in type promotion which prevented the initializer expression
(`i == null`) from being accounted for when the variable in question
(`iIsNull`) lacked an explicit type.
To avoid causing problems for packages that are intended to work with older
versions of Dart, the fix only takes effect when the minimum SDK of the source
packages is 2.15 or greater.
[#1785]: https://github.com/dart-lang/language/issues/1785
- Restrictions on members of a class with a constant constructor are relaxed
such that they only apply when the class has a _generative_ constant
constructor. For example, this used to be an error, but is now permitted:
```dart
abstract class A {
const factory A() = B;
var v1;
late final v2 = Random().nextInt(10);
late final v3;
}
class B implements A {
const B([this.v3 = 1]);
get v1 => null;
set v1(_) => throw 'Cannot mutate B.v1';
final v2 = 0;
final v3;
set v3(_) => throw 'Cannot initialize B.v3';
}
```
This implements a relaxation of the specified rule for a `late final`
instance variable, and it brings the implementation behavior in line with
the specification in all other cases.
- **Function object canonicalization and equality**: Several corner cases in the
area of function object canonicalization and function object equality have
been updated, such that all tools behave in the same way, and the behavior
matches the specification.
In particular, function objects are now equal when they are obtained by
generic instantiation from the same function with the same actual type
arguments, even when that type argument is not known at compile time.
When the expressions are constant then the function objects are identical.
Constant expressions are treated as such even when they do not occur in a
constant context (e.g., `var f = top;`).
### Core libraries
#### `dart:async`
- Make the `unawaited` function's argument nullable, to allow calls like
`unawaited(foo?.bar())`.
#### `dart:cli`
- The experimental `waitFor` functionality, and the library containing only that
function, are now deprecated.
#### `dart:core`
- Add extension `name` getter on enum values.
- Add `Enum.compareByIndex` helper function for comparing enum values by index.
- Add `Enum.compareByName` helper function for comparing enum values by name.
- Add extension methods on `Iterable<T extends Enum>`, intended for
`SomeEnumType.values` lists, to look up values by name.
- Deprecate `IntegerDivisionByZeroException`.
Makes the class also implement `Error`. Code throwing the exception will be
migrated to throwing an `Error` instead until the class is unused and
ready to be removed.
Code catching the class should move to catching `Error` instead
(or, for integers, check first for whether it's dividing by zero).
#### `dart:ffi`
- Add `Bool` native type.
#### `dart:io`
- **Breaking change** [#46875](https://github.com/dart-lang/sdk/issues/46875):
The `SecurityContext` class in `dart:io` has been updated to set the minimum
TLS protocol version to TLS1_2_VERSION (1.2) instead of TLS1_VERSION.
- Add `RawSocket.sendMessage`, `RawSocket.receiveMessage` that allow passing of
file handle references via Unix domain sockets.
#### `dart:js_util`
- The `js_util` methods `setProperty`, `callMethod`, and `callConstructor` have
been optimized to remove checks on arguments when the checks can be elided.
Also, those methods, along with `getProperty` and `newObject`, now support a
generic type argument to specify a return type. These two changes make simple
`js_util` usage, like reading and writing primitive properties or calling
methods with simple arguments, have zero overhead.
#### `dart:web_sql`
- **Breaking change** [#46316](https://github.com/dart-lang/sdk/issues/46316):
The WebSQL standard was abandoned more than 10
years ago and is not supported by many browsers. This release completely
deletes the `dart:web_sql` library.
#### `dart:html`
- **Breaking change** [#46316](https://github.com/dart-lang/sdk/issues/46316):
Related to the removal of `dart:web_sql` (see above), `window.openDatabase`
has been removed.
### Tools
#### Dart command line
- **Breaking change** [#46100][]: The standalone `dart2native` tool has been
removed as previously announced. Its replacements are the
`dart compile exe` and `dart compile aot-snapshot` commands, which offer the
same functionality.
- **Breaking change**: The standalone `dartfmt` tool has been removed as
previously announced. Its replacement is the `dart format` command.
Note that `dart format` has [a different set of options and
defaults][dartfmt cli] than `dartfmt`.
- When a script is `dart run` it will always be precompiled, but with
incremental precompilation for following runs.
#### Dart VM
- **Breaking change** [#45451](https://github.com/dart-lang/sdk/issues/45451):
Support for `dart-ext:`-style native extensions has been removed as previously
announced. Use `dart:ffi` to bind to native libraries instead.
- **Breaking change** [#46754](https://github.com/dart-lang/sdk/issues/46754):
Isolates spawned via the `Isolate.spawn()` API are now grouped, operate on the
same managed heap and can therefore share various VM-internal data structures.
This leads to ~100x faster isolate startup latency, ~10-100x lower
per-isolate base memory overhead and ~8x faster inter-isolate communication.
Making isolates operate on the same heap will also make them collaborate on
garbage collections, which changes performance characteristics for GC-heavy
applications that may - in rare cases - negatively affect pause times or
throughput.
- Allow closures both in inter-isolate messages as well as as entrypoints in
`Isolate.spawn(<entrypoint>, ...)` calls. Closures and their enclosing context
may need to be copied in this process. The enclosing context is - as with
normal messages - verified to only contain objects that are sendable.
Note of caution: The Dart VM's current representation of enclosing variables
in closures can make closures hang on to more variables than strictly needed.
Using such closures in inter-isolate communication can therefore lead to
copying of larger transitive object graphs. If the extended transitive
closure includes objects that are illegal to send, the sending will fail.
See [#36983](https://github.com/dart-lang/sdk/issues/36983), which tracks this
existing memory leak issue.
#### Linter
Updated the Linter to `1.14.0`, which includes changes that
- improves performance for `annotate_overrides`, `prefer_contains`, and
`prefer_void_to_null`.
- marks `avoid_dynamic_calls` stable.
- fixed `avoid_null_checks_in_equality_operators` false positive with
non-nullable params.
- update `avoid_print` to allow `kDebugMode`-wrapped print calls.
- adds support for constructor tear-offs to `avoid_redundant_argument_values`,
`unnecessary_lambdas`, and `unnecessary_parenthesis`.
- improves messages for `avoid_renaming_method_parameters`.
- improves regular expression parsing performance for common checks
(`camel_case_types`, `file_names`, etc.).
- fixed `file_names` to report at the start of the file
(not the entire compilation unit).
- allow `while (true) { ... }` in `literal_only_boolean_expressions`.
- fixed `omit_local_variable_types` false positives.
- fixed `omit_local_variable_types` to not flag a local type that is required
for inference.
- fixed `overridden_fields` false positive with static fields.
- fixed `prefer_collection_literals` named typed parameter false positives.
- fixed `prefer_const_constructors` false positive for deferred imports.
- fixed `prefer_final_parameters` handling of initializing formals.
- fixed `prefer_generic_function_type_aliases` false positives with incomplete
statements.
- fixed `prefer_initializing_formals` false positives with factory constructors.
- fixed `prefer_void_to_null` false positive with overridden properties.
- fixed `prefer_void_to_null` false positives on overriding returns.
- fixed `prefer_void_to_null` false positives.
- adds a new lint: `unnecessary_constructor_name` to flag unnecessary uses of
`.new`.
- updates `unnecessary_getters_setters` to only flag the getter.
- fixed `unnecessary_parenthesis` false positive with function expressions.
- fixed `use_build_context_synchronously` false positive in awaits inside
anonymous functions.
- improve control flow analysis for `use_build_context_synchronously`.
- fixed `use_rethrow_when_possible` false positives.
- fixed `void_checks` false positives with incomplete source.
### Pub
- If you have analytics enabled `dart pub get` will send
[usage metrics](https://github.com/dart-lang/pub/blob/0035a40f25d027130c0314571da53ffafc6d973b/lib/src/solver/result.dart#L131-L175)
for packages from pub.dev, intended for popularity analysis.
- Adds support for token-based authorization to third-party package-repositories
with the new command `dart pub token`.
- Credentials are no longer stored in the pub-cache, but in a platform dependent
config directory:
* On Linux `$XDG_CONFIG_HOME/dart/pub-credentials.json` if `$XDG_CONFIG_HOME`
is defined, otherwise `$HOME/.config/dart/pub-credentials.json`
* On Mac OS: `$HOME/Library/Application Support/dart/pub-credentials.json`
* On Windows: `%APPDATA%/dart/pub-credentials.json`
- The syntax for dependencies hosted at a third-party package repository has
been simplified. Before you would need to write:
```yaml
dependencies:
colorizer:
hosted:
name: colorizer
url: 'https://custom-pub-server.com'
version: ^1.2.3
environment:
sdk: '>=2.14.0 < 3.0.0'
```
Now you can write:
```yaml
dependencies:
colorizer:
hosted: 'https://custom-pub-server.com'
version: ^1.2.3
environment:
sdk: '>=2.15.0 < 3.0.0'
```
This feature requires
[language-version](https://dart.dev/guides/language/evolution#language-versioning)
2.15 or later, e.g. the `pubspec.yaml` should have an SDK constraint of
`>=2.15 <3.0.0`.
- Detect potential leaks in `dart pub publish`.
When publishing, pub will examine your files for potential secret keys, and
warn you.
To ignore a file that has a false positive, add it to a
[`false_secrets`](https://dart.dev/go/false-secrets) section of your
`pubspec.yaml`.
- Fixes unicode terminal detection windows.
- New flag `--example` to the commands
`dart pub get/upgrade/downgrade/add/remove` that will result in the `example/`
folder dependencies to be updated after operating in the current directory.
### Other libraries
#### `package:js`
- Extensions on JS interop or native `dart:html` classes can now declare
members as `external`. These members are equivalent to regular extension
members that use `js_util` to expose the underlying JavaScript.
## 2.14.4 - 2021-10-14
This is a patch release that fixes:
- a memory leak of analyzer plugins (issue [flutter/flutter#90868][]).
- the Dart VM sometimes loading expired certificates on Windows (issues
[#46370][] and [#47420][]).
[flutter/flutter#90868]: https://github.com/flutter/flutter/issues/90868
[#46370]: https://github.com/dart-lang/sdk/issues/46370
[#47420]: https://github.com/dart-lang/sdk/issues/47420
## 2.14.3 - 2021-09-30
This is a patch release that fixes:
- a code completion performance regression (issue
[flutter/flutter-intellij#5761][]).
- debug information emitted by the Dart VM (issue [#47289][]).
[flutter/flutter-intellij#5761]:
https://github.com/flutter/flutter-intellij/issues/5761
[#47289]: https://github.com/dart-lang/sdk/issues/47289
## 2.14.2 - 2021-09-16
This is a patch release that fixes:
- two dartdoc crashes (issues [dart-lang/dartdoc#2740][] and
[dart-lang/dartdoc#2755][]).
- error messages when using the `>>>` operator on older language versions
(issue [#46886][]).
- invalid `pubspec.lock` paths on Windows (issue [dart-lang/pub#3012][]).
[dart-lang/dartdoc#2740]: https://github.com/dart-lang/dartdoc/issues/2740
[dart-lang/dartdoc#2755]: https://github.com/dart-lang/dartdoc/issues/2755
[#46886]: https://github.com/dart-lang/sdk/issues/46886
[#45767]: https://github.com/dart-lang/sdk/issues/45767
[dart-lang/pub#3012]: https://github.com/dart-lang/pub/issues/3012
## 2.14.1 - 2021-09-09
- Fixed an issue specific to the macOS ARM64 (Apple Silicon) SDK, where the Dart
commandline tools did not have the expected startup performance.
## 2.14.0 - 2021-09-09
### Language
- Add an unsigned shift right operator `>>>`. Pad with zeroes, ignoring the sign
bit. On the web platform `int.>>>` shifts the low 32 bits interpreted as an
unsigned integer, so `a >>> b` gives the same result as
`a.toUnsigned(32) >>> b` on the VM.
- Prior to Dart 2.14, metadata (annotations) were not permitted to be specified
with generic type arguments. This restriction is lifted in Dart 2.14.
```dart
class C<T> {
const C();
}
@C(); // Previously permitted.
@C<int>(); // Previously an error, now permitted.
```
- Prior to Dart 2.14, generic function types were not permitted as arguments to
generic classes or functions, nor to be used as generic bounds. This
restriction is lifted in Dart 2.14.
```dart
T wrapWithLogging<T>(T f) {
if (f is void Function<T>(T x)) {
return <S>(S x) {
print("Call: f<$S>($x)");
var r = f<S>(x);
print("Return: $x");
return r;
} as T;
} // More cases here
return f;
}
void foo<T>(T x) {
print("Foo!");
}
void main() {
// Previously an error, now permitted.
var f = wrapWithLogging<void Function<T>(T)>(foo);
f<int>(3);
}
```
### Core libraries
#### `dart:async`
- The uncaught error handlers of `Zone`s are now run in the parent zone of the
zone where they were declared. This prevents a throwing handler from causing
an infinite loop by repeatedly triggering itself.
- Added `ignore()` as extension member on futures.
- Added `void unawaited(Future)` top-level function to deal with the
`unawaited_futures` lint.
#### `dart:core`
- Introduce `Enum` interface implemented by all `enum` declarations.
- The native `DateTime` class now better handles local time around daylight
saving changes that are not precisely one hour. (No change on the Web which
uses the JavaScript `Date` object.)
- Adds static methods `hash`, `hashAll` and `hashAllUnordered` to the `Object`
class. These can be used to combine the hash codes of multiple objects in a
consistent way.
- The `Symbol` constructor now accepts any string as argument. Symbols are equal
if they were created from the same string.
#### `dart:ffi`
- Add the `DynamicLibrary.providesSymbol` function to check whether a symbol is
available in a dynamic library.
- Add `Union` native type for interacting with unions in native memory.
#### `dart:html`
- `convertNativeToDart_Dictionary()` now converts objects recursively, this
fixes APIs like MediaStreamTrack.getCapabilities that convert between Maps and
browser Dictionaries. [#44319]
- Added some access-control HTTP header names to `HttpHeaders`.
[#44319]: https://github.com/dart-lang/sdk/issues/44319
#### `dart:io`
- BREAKING CHANGE (for pre-migrated null safe code): `HttpClient`'s
`.authenticate` and `.authenticateProxy` setter callbacks must now accept a
nullable `realm` argument.
- Added some access-control HTTP header names to `HttpHeaders`.
#### `dart:typed_data`
- **BREAKING CHANGE** (https://github.com/dart-lang/sdk/issues/45115) Most types
exposed by this library can no longer be extended, implemented or mixed-in.
The affected types are `ByteBuffer`, `TypedData` and _all_ its subclasses,
`Int32x4`, `Float32x4`, `Float64x2` and `Endian`.
#### `dart:web_sql`
- `dart:web_sql` is marked deprecated and will be removed in an upcoming
release. Also the API `window.openDatabase` in `dart:html` is deprecated as
well.
This API and library was exposing the WebSQL proposed standard. The standard
was abandoned more than 5 years ago and is not supported by most browsers. The
`dart:web_sql` library has been documented as unsupported and deprecated for
many years as well and but wasn't annotated properly until now.
### Dart VM
- **Breaking change** [#45071][]: `Dart_NewWeakPersistentHandle`'s and
`Dart_NewFinalizableHandle`'s `object` parameter no longer accepts `Pointer`s
and subtypes of `Struct`. Expandos no longer accept `Pointer`s and subtypes of
`Struct`s.
[#45071]: https://github.com/dart-lang/sdk/issues/45071
### Tools
#### Dart command line
- **Breaking change** [#46100][]: The standalone `dart2native` tool has been
marked deprecated, and now prints a warning message. Its replacements are the
`dart compile exe` and `dart compile aot-snapshot` commands, which offer the
same functionality. The `dart2native` tool will be removed from the Dart SDK
in Dart 2.15.
- **Breaking change**: The standalone `dartfmt` tool has been marked deprecated,
and now prints a warning message. Instead, use `dart format`. The `dartfmt`
tool will be removed from the Dart SDK in Dart 2.15.
Note that `dart format` has [a different set of options and
defaults][dartfmt cli] than `dartfmt`.
- The `dart create` command has been updated to create projects that use the new
'recommended' set of lints from `package:lints`. See
https://dart.dev/go/core-lints for more information about these lints.
[#46100]: https://github.com/dart-lang/sdk/issues/46100
[dartfmt cli]: https://github.com/dart-lang/dart_style/wiki/CLI-Changes
- The `dart analyze` command has been extended to support specifying multiple
files or directories to analyze; see also
https://github.com/dart-lang/sdk/issues/45352.
- The `dartanalyzer` command's JSON output mode has been changed to emit the
JSON output on stdout instead of stderr.
#### dart format
- Simplify and optimize cascade formatting. See:
https://github.com/dart-lang/dart_style/pull/1033
- Don't unnecessarily split argument lists with `/* */` comments.
- Return correct exit code from `FormatCommand` when formatting stdin.
- Split empty catch blocks with finally clauses or catches after them.
#### Linter
Updated the Linter to `1.8.0`, which includes changes that
- improve performance for `prefer_is_not_empty`.
- fix false positives in `no_logic_in_create_state`.
- improve `package_names` to allow dart identifiers as package names.
- fix a false-positive in `package_names` (causing keywords to wrongly get flagged).
- fix `avoid_classes_with_only_static_member` to check for inherited members and also
flag classes with only methods.
- fix `curly_braces_in_flow_control_structures` to properly flag terminating `else-if`
blocks.
- improve `always_specify_types` to support type aliases.
- fix a false positive in `unnecessary_string_interpolations` w/ nullable interpolated
strings
- fix a false positive in `avoid_function_literals_in_foreach_calls` for nullable
iterables.
- fix false positives in `avoid_returning_null` w/ NNBD
- fix false positives in `use_late_for_private_fields_and_variables` in the presence
of const constructors.
- adds a new lint: `eol_at_end_of_file`.
- fix case-sensitive false positive in `use_full_hex_values_for_flutter_colors`.
- improve try-block and switch statement flow analysis for
`use_build_context_synchronously`.
- update `use_setters_to_change_properties` to only highlight a method name, not
the entire body and doc comment.
- update `unnecessary_getters_setters` to allow otherwise "unnecessary" getters
and setters with annotations.
- update `missing_whitespace_between_adjacent_strings` to allow String
interpolations at the beginning and end of String literals.
- update `unnecessary_getters_setters` to allow for setters with non-basic
assignments (for example, `??=` or `+=`).
- relax `non_constant_identifier_names` to allow for a trailing underscore.
- fix false negative in `prefer_final_parameters` where first parameter is
final.
- improve `directives_ordering` sorting of directives with dot paths and
dot-separated package names.
- (internal) migrate to `SecurityLintCode` instead of deprecated
`SecurityLintCodeWithUniqueName`.
- (internal) fix `avoid_types_as_parameter_names` to skip field formal
parameters.
- fix false positives in `prefer_interpolation_to_compose_strings` where the
left operand is not a String.
- fix false positives in `only_throw_errors` for misidentified type variables.
- add new lint: `depend_on_referenced_packages`.
- update `avoid_returning_null_for_future` to skip checks for null-safe
libraries.
- add new lint: `use_test_throws_matchers`.
- relax `sort_child_properties_last` to accept closures after child.
- improve performance for `prefer_contains` and `prefer_is_empty`.
- add new lint: `noop_primitive_operations`.
- mark `avoid_web_libraries_in_flutter` as stable.
- add new lint: `prefer_final_parameters`.
- update `prefer_initializing_formals` to allow assignments where identifier
names don't match.
- update `directives_ordering` to checks ordering of `package:` imports in code
outside pub packages.
- add simple reachability analysis to `use_build_context_synchronously` to
short-circuit await-discovery in terminating blocks.
- update `use_build_context_synchronously` to recognize nullable types when
accessed from legacy libraries.
#### Pub
- `dart pub publish` now respects `.pubignore` files with gitignore-style rules.
`.gitignore` files in the repo are still respected if they are not overridden
by a `.pubignore` in the same directory.
pub no longer queries git for listing the files. This implies:
- Checked in files will now be ignored if they are included by a `.gitignore`
rule.
- Global ignores are no longer taken into account.
- Even packages that are not in git source control will have their
`.gitignore` files respected.
- `.gitignore` and `.pubignore` is always case-insensitive on MacOs and
Windows (as is default for `git` repositories).
- New flag `dart pub deps --json` gives a machine parsable overview of the
current dependencies.
- New command: `dart pub cache clean`. Will delete everything in your current
pub cache.
- Commands related to a single package now takes a `--directory` option to
operate on a package in the given directory instead of the working directory.
- git dependencies with a relative repo url would previously be interpreted
relative to the current package, even for transitive dependencies. This now
fails instead.
- Pub now uses a Dart library to read and write tar files. This should fix
several issues we had with incompatibilities between different system `tar`s.
- `PUB_HOSTED_URL` can now include a trailing slash.
- Incremental compilation is now used for compilation of executables from
dependencies when using `dart run <package>:<command>`.
#### Dart2JS
* **Breaking change** [#46545][]: Dart2JS emits ES6+ JavaScript by default,
thereby no longer supporting legacy browsers. Passing the
`--legacy-javascript` flag will let you opt out of this update, but this
flag will be removed in a future release. Modern browsers will not be
affected, as Dart2JS continues to support [last two major releases][1] of
Edge, Safari, Firefox, and Chrome.
[#46545]: https://github.com/dart-lang/sdk/issues/46545
[1]: https://dart.dev/faq#q-what-browsers-do-you-support-as-javascript-compilation-targets
#### Dart Dev Compiler (DDC)
- **Breaking change** [#44154][]: Subtyping relations of `package:js` classes
have been changed to be more correct and consistent with Dart2JS.
Like `anonymous` classes, non-`anonymous` classes will no longer check the
underlying type in DDC. The internal type representation of these objects have
changed as well, which will affect the `toString` value of these types.
[#44154]: https://github.com/dart-lang/sdk/issues/44154
## 2.13.4 - 2021-06-28
This is a patch release that fixes:
- a Dart VM compiler crash (issue [flutter/flutter#84212][]).
- a DDC compiler crash (issue [flutter/flutter#82838][]).
[flutter/flutter#84212]: https://github.com/flutter/flutter/issues/84212
[flutter/flutter#82838]: https://github.com/flutter/flutter/issues/82838
## 2.13.3 - 2021-06-10
This is a patch release that fixes:
- a Dart compiler crash (issue [flutter/flutter#83094][]).
- an analysis server deadlock causing it to stop responding to IDE requests
(issue [#45996][]).
- an analyzer crash when analyzing against `package:meta` `v1.4.0` (issue
[#46183][]).
[flutter/flutter#83094]: https://github.com/flutter/flutter/issues/83094
[#45996]: https://github.com/dart-lang/sdk/issues/45996
[#46183]: https://github.com/dart-lang/sdk/issues/46183
## 2.13.1 - 2021-05-25
This is a patch release that fixes:
- incorrect behavior in CastMap (issue [#45473][]).
- missing nullability from recursive type hierarchies in DDC (issue [#45767][]).
[#45473]: https://github.com/dart-lang/sdk/issues/45473
[#45767]: https://github.com/dart-lang/sdk/issues/45767
## 2.13.0 - 2021-05-18
### Language
- **Type aliases** [Non-function type aliases][]: Type aliases (names for types
introduced via the `typedef` keyword) were previously restricted to only
introduce names for function types. In this release, we remove this
restriction and allow type aliases to name any kind of type.
```dart
import 'dart:convert';
typedef JsonMap = Map<String, dynamic>;
JsonMap parseJsonMap(String input) => json.decode(input) as JsonMap;
```
In addition to being usable as type annotations, type aliases that name class
types can now also be used anywhere that the underlying class could be used,
allowing type aliases to be used to safely rename existing classes.
```dart
class NewClassName<T> {
NewClassName.create(T x);
static NewClassName<T> mkOne<T>(T x) => NewClassName<T>.create(x);
}
@Deprecated("Use NewClassName instead")
typedef OldClassName<T> = NewClassName<T>;
class LegacyClass extends OldClassName<int> {
LegacyClass() : super.create(3);
}
OldClassName<int> legacyCode() {
var one = OldClassName.create(1);
var two = OldClassName.mkOne(2);
return LegacyClass();
}
```
The new type alias feature is only available as part of the 2.13
[language version](https://dart.dev/guides/language/evolution). To use this
feature, you must set the lower bound on the sdk constraint for your package
to 2.13 or greater.
[non-function type aliases]:
https://github.com/dart-lang/language/blob/master/accepted/2.13/nonfunction-type-aliases/feature-specification.md
### Core libraries
#### `dart:collection`
- The `SplayTreeMap` was changed to allow `null` as key if the `compare`
function allows it. It now checks that a new key can be used as an argument to
the `compare` function when the member is added, _even if the map is empty_
(in which case it just compares the key to itself).
- The `SplayTreeSet` was changed to checks that a new element can be used as an
argument to the `compare` function when the member is added, _even if the set
is empty_ (in which case it just compares the element to itself).
#### `dart:developer`
- Added `serverWebSocketUri` property to `ServiceProtocolInfo`.
#### `dart:ffi`
- Add `Packed` for interacting with packed structs in native memory.
- Add `Array` for interacting with structs with inline arrays.
### Dart VM
### Tools
#### Analyzer
- Static analyses with "error" severity can once again be ignored with comments
like `// ignore: code` and `// ignore_for_file: code`. To declare that certain
analysis codes, or codes with certain severities ("error", "warning", and
"info") cannot be ignored with such comments, list them in
`analysis_options.yaml`, under the `analyzer` heading, with a new YAML key,
`cannot-ignore`. For example, to declare that "error" codes and
`unused_import` cannot be ignored, write the following into
`analysis_options.yaml`:
```yaml
analyzer:
cannot-ignore:
- error
- unused_import
```
#### dart format
- Correct constructor initializer indentation after `required` named parameters.
#### Linter
Updated the Linter to `1.2.1`, which includes:
- Improved `iterable_contains_unrelated_type` to better support `List` content
checks.
- Fixed `camel_case_types` and `prefer_mixin` to support non-function type
aliases.
- Fixed `prefer_mixin` to properly make exceptions for `dart.collection` legacy
mixins.
- Added new lints `avoid_multiple_declarations_per_line`,
`use_if_null_to_convert_nulls_to_bools`, `deprecated_consistency`,
`use_named_constants`, `use_build_context_synchronously` (experimental).
- Deprecated `avoid_as`.
- Migrated library to null-safety.
### Other libraries
#### `package:js`
- **Breaking change:** It is no longer valid to use `String`s that match an
`@Native` annotation in an `@JS()` annotation for a non-anonymous JS interop
class. This led to erroneous behavior due to the way interceptors work. If you
need to work with a native class, prefer `dart:html`, an `@anonymous` class,
or `js_util`. See issue [#44211][] for more details.
[#44211]: https://github.com/dart-lang/sdk/issues/44211
## 2.12.4 - 2021-04-15
This is a patch release that fixes a Dart VM compiler crashes when compiling
initializers containing async closures (issue [#45306][]).
[#45306]: https://github.com/dart-lang/sdk/issues/45306
## 2.12.3 - 2021-04-14
**Security advisory**: This is a patch release that fixes a vulnerability in
`dart:html` related to DOM clobbering. See the security advisory
[CVE-2021-22540][cve-2021-22540] for more details. Thanks again to **Vincenzo di
Cicco** for finding and reporting this vulnerability.
[cve-2021-22540]:
https://github.com/dart-lang/sdk/security/advisories/GHSA-3rfv-4jvg-9522
## 2.12.2 - 2021-03-17
This is a patch release that fixes crashes reported by Flutter 2 users (issue
[flutter/flutter#78167][]).
[flutter/flutter#78167]: https://github.com/flutter/flutter/issues/78167
## 2.12.1 - 2021-03-10
This is a patch release that fixes:
- an unhandled exception in HTTPS connections (issue [#45047][]).
- a typing issue in the typed_data `+` operator (issue [#45140][]).
[#45047]: https://github.com/dart-lang/sdk/issues/45047
[#45140]: https://github.com/dart-lang/sdk/issues/45140
## 2.12.0 - 2021-03-03
### Language
- **Breaking change** [Null safety][] is now enabled by default in all code that
has not opted out. With null safety, types in your code are non-nullable by
default. Null can only flow into parts of your program where you want it. With
null safety, your runtime null-dereference bugs turn into edit-time analysis
errors.
You can opt out of null safety and preserve your code's previous behavior by
setting the lower bound of the SDK constraint in your pubspec to 2.11.0 or
earlier to request an earlier [language version][]. You can opt out individual
Dart files by adding `// @dart=2.11` to the beginning of the file.
Files that are opted in to null safety may report new compile-time errors.
Opting in to null safety also gives you access to other new language features:
- Smarter flow analysis and type promotion
- `required` named parameters
- `late` variables
- The postfix `!` null assertion operator
- The `?..` and `?[]` null-aware operators
- **Breaking change** [#44660][]: Fixed an implementation bug where `this` would
sometimes undergo type promotion in extensions.
[null safety]: https://dart.dev/null-safety/understanding-null-safety
[language version]:
https://dart.dev/guides/language/evolution#language-versioning
[#44660]: https://github.com/dart-lang/sdk/issues/44660
### Core libraries
#### `dart:async`
- Add extension method `onError()` on `Future` to allow better typing of error
callbacks.
#### `dart:collection`
- Add `UnmodifiableSetView` class, which allows users to guarantee that methods
that could change underlying `Set` instance can not be invoked.
- Make it explicit that `LinkedList` compares elements by identity, and update
`contains()` to take advantage of this.
#### `dart:core`
- Add `Set.unmodifiable()` constructor, which allows users to create
unmodifiable `Set` instances.
#### `dart:ffi`
- **Breaking change** [#44621][]: Invocations with a generic `T` of `sizeOf<T>`,
`Pointer<T>.elementAt()`, `Pointer<T extends Struct>.ref`, and
`Pointer<T extends Struct>[]` are being deprecated in the current stable
release (2.12), and are planned to be fully removed in the following stable
release (2.13). Consequently, `allocate` in `package:ffi` will no longer be
able to invoke `sizeOf<T>` generically, and will be deprecated as well.
Instead, the `Allocator` it is introduced to `dart:ffi`, and also requires a
constant `T` on invocations. For migration notes see the breaking change
request.
- **Breaking change** [#44622][]: Subtypes of `Struct` without any native member
are being deprecated in the current stable release (2.12), and are planned to
be fully removed in the following stable release (2.13). Migrate opaque types
to extend `Opaque` rather than `Struct`.
[#44621]: https://github.com/dart-lang/sdk/issues/44621
[#44622]: https://github.com/dart-lang/sdk/issues/44622
#### `dart:io`
- `HttpRequest` now correctly follows HTTP 308 redirects
(`HttpStatus.permanentRedirect`).
#### `dart:isolate`
- Add `debugName` positional parameter to `ReceivePort` and `RawReceivePort`
constructors, a name which can be associated with the port and displayed in
tooling.
- Introduce `Isolate.exit([port, message])` which terminates current isolate
and, if `port` is specified, as a last action sends out the `message` out to
that `port`.
#### `dart:html`
- `EventStreamSubscription.cancel` has been updated to retain its synchronous
timing when running in both sound and unsound null safety modes. See issue
[#44157][] for more details.
[#44157]: https://github.com/dart-lang/sdk/issues/44157
### Dart VM
- **Breaking change** [#42312][]: `Dart_WeakPersistentHandle`s no longer
auto-delete themselves when the referenced object is garbage collected to
avoid race conditions, but they are still automatically deleted when the
isolate group shuts down.
- **Breaking change** [#42312][]: `Dart_WeakPersistentHandleFinalizer` is
renamed to `Dart_HandleFinalizer` and had its `handle` argument removed. All
API functions using that type have been updated.
[#42312]: https://github.com/dart-lang/sdk/issues/42312
### Dart2JS
- Remove `--no-defer-class-types` and `--no-new-deferred-split`.
### Tools
#### Analyzer
- Remove the `--use-fasta-parser`, `--preview-dart-2`, and
`--enable-assert-initializers` command line options. These options haven't
been supported in a while and were no-ops.
- Report diagnostics regarding the
[`@internal`](https://pub.dev/documentation/meta/latest/meta/internal-constant.html)
annotation.
- Improve diagnostic-reporting regarding the
[`@doNotStore`](https://pub.dev/documentation/meta/latest/meta/doNotStore-constant.html)
annotation.
- Introduce a diagnostic which is reported when a library member named `main` is
not a function.
- Introduce a diagnostic which is reported when a `main` function's first
parameter is not a supertype of `List<String>`.
- Introduce diagnostics for when an `// ignore` comment contains an error code
which is not being reported, cannot be ignored, or is already being ignored.
- Report diagnostics when using
[`@visibleForTesting`](https://pub.dev/documentation/meta/latest/meta/
visibleForTesting-constant.html) on top-level variables.
- Fix false positive reports of "unused element" for top-level setters and
getters.
- Fix false positive reports regarding `@deprecated` field formal parameters at
their declaration.
- For null safety, introduce a diagnostic which reports when a null-check will
always fail.
- Fix false positive reports regarding optional parameters on private
constructors being unused.
- Introduce a diagnostic which is reported when a constructor includes duplicate
field formal parameters.
- Improve the "unused import" diagnostic when multiple import directives share a
common prefix.
- Fix false positive "unused import" diagnostic regarding an import which
provides an extension method which is used.
- For null safety, improve the messaging of "use of nullable value" diagnostics
for eight different contexts.
- Fix false positive reports regarding `@visibleForTesting` members in a "hide"
combinator of an import or export directive.
- Improve the messaging of "invalid override" diagnostics.
- Introduce a diagnostic which is reported when `Future<T>.catchError` is called
with an `onError` callback which does not return `FutureOr<T>`.
#### dartfmt
- Don't duplicate comments on chained if elements.
- Preserve `?` in initializing formal function-typed parameters.
- Fix performance issue with constructors that have no initializer list.
#### Linter
Updated the Linter to `0.1.129`, which includes: