mirror of
https://github.com/dart-lang/sdk
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5249cd9294
Tested: Standard CQ Change-Id: Ic52d4d38a5b117dfcdc778dedfac08315ca30a54 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/251541 Commit-Queue: Alexander Thomas <athom@google.com> Reviewed-by: William Hesse <whesse@google.com>
283 lines
8.6 KiB
YAML
283 lines
8.6 KiB
YAML
# Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
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# for details. All rights reserved. Use of this source code is governed by a
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# BSD-style license that can be found in the LICENSE file.
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# Experimental features are described in docs/process/experimental-flags.md
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# (Despite the name, they are not really intended for experiments.)
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# They are intended to enable new features or enhancements that are being
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# developed and are not yet shipped. Experimental feature flags are expected
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# to be relatively short-lived.
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#
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# ### Code Generation
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#
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# When you change this file, run the following to update analyzer, kernel, and
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# vm:
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#
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# analyzer:
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# dart pkg/analyzer/tool/experiments/generate.dart
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#
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# kernel:
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# pkg/front_end/tool/fasta generate-experimental-flags
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#
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# vm:
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# dart tools/generate_experimental_flags.dart
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#
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# ### Overview
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#
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# This document consists mostly of a map called "features".
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# Each entry in this map corresponds to an experiment,
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# and contains the following parts:
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#
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# 1. help: (required text)
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# A human readable description of the experiment.
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#
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# 2. enabledIn: (optional #.#)
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# The Dart SDK version (<major>.<minor>) in which the experiment is shipping.
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#
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# If this field is specified, then the experiment is enabled regardless of
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# the actual version of the SDK. If this field is omitted, then the
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# experiment is disabled by default, but may be enabled by specifying the
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# flag on the command line. (e.g. --enable-experiment=non-nullable)
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#
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# A version less than this version may be specified in a .packages file
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# or in a library language version override (e.g. // @dart = 2.1)
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# to disable this feature. For more on library language version override, see
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# https://github.com/dart-lang/language/blob/master/accepted/future-releases/language-versioning/language-versioning.md
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#
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# 3. expired: (optional boolean)
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# If true, then the experiment can no longer be enabled by specifying the
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# flag on the command line, and the corresponding entry is slated for
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# eventual removal from this file. If this field is omitted, then 'expired'
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# is considered to be false.
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#
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# 4. validation: (optional string)
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# If provided this should be a program that prints "feature enabled" on
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# stdout if the feature is enabled, and throws or fails to compile otherwise.
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# The intended use for this is to be able to run generic tests for each
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# experiment.
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#
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# Using the above fields, experiments pass through several states:
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#
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# Disabled:
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# When an experiment is first added to this file, the 'enabledIn' and
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# 'expired' fields are omitted and the experiment is disabled by default,
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# but may be enabled by specifying the flag on the command line.
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# The implementation teams begin building support for the feature,
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# guarded by the flag. Users can enable the flag and begin to try out
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# the feature as it is being developed.
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#
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# Experimental release:
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# When an experiment is released, then the 'experimentalReleaseVersion' field
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# is added indicating which version of the SDK contains this new language
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# feature for libraries and packages in mentioned in
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# `sdk/lib/_internal/allowed_experiments.json`. For other libraries and
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# packages, passing the experiment flag is still required to turn on the
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# experiment.
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#
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# Shipped:
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# When an experiment is shipped, then the 'enabledIn' field is added
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# indicating which version of the SDK contains this new language feature.
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# At this point, specifying the flag on the command line has no effect because
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# the experiment is enabled by default and cannot be disabled.
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#
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# Retired or Rejected:
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# At some point, the 'expired' field is added to the experiment indicating
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# that the flag is to be retired if the experiment has shipped or that the
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# entire experiment was rejected if the experiment has not shipped. It also
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# indicates that the corresponding entry is slated for eventual removal
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# from this file. Users specifying this flag on the command line should receive
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# a warning that the experiment has been retired or rejected, but the tool
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# should continue to run.
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#
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# In addition, there is also a value called "current-version"
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# specifying the version of Dart that is currently being developed.
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# Dart source files that don't specify their own version will be
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# presumed to be in this version. Experiment flags will not affect
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# files that specify an earlier version.
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#
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# Furthermore, most of the above was designed with language features
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# (spanning both CFE and Analyzer) in mind, but didn't take into account
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# features in individual products (e.g. in CFE that has no influence on
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# Analyzer). As a stepping-stone to allow for this usage as well, a "category"
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# is also available. If no "category" is specified it's assumed to be the
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# default 'language' "category" with code generated for both CFE and Analyzer,
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# while other categories can be tailored more specifically.
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current-version: '2.19.0'
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features:
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variance:
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help: "Sound variance"
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alternative-invalidation-strategy:
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help: "Alternative invalidation strategy for incremental compilation."
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category: "CFE"
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value-class:
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help: "Value class"
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extension-types:
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help: "Extension Types"
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const-functions:
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help: "Allow more of the Dart language to be executed in const expressions."
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macros:
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help: "Static meta-programming"
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inference-update-2:
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help: "Type promotion for fields"
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# Experiment flag only used for testing.
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test-experiment:
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help: >-
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Has no effect. Can be used for testing the --enable-experiment
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command line functionality.
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#
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# Flags below this line are shipped, retired, or rejected, cannot be specified
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# on the command line, and will eventually be removed.
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#
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nonfunction-type-aliases:
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help: "Type aliases define a <type>, not just a <functionType>"
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enabledIn: '2.13.0'
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validation: |
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typedef S = String;
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void main() {
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S s = 'feature enabled';
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print(s);
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}
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expired: true
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non-nullable:
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help: "Non Nullable by default"
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experimentalReleaseVersion: '2.10.0'
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enabledIn: '2.12.0'
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validation: |
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void main() {
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int? a = null;
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print('feature enabled');
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}
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expired: true
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extension-methods:
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help: "Extension Methods"
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enabledIn: '2.6.0'
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expired: true
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constant-update-2018:
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help: "Enhanced constant expressions"
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enabledIn: '2.0.0'
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expired: true
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control-flow-collections:
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help: "Control Flow Collections"
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enabledIn: '2.0.0'
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expired: true
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generic-metadata:
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help: >-
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Allow annotations to accept type arguments;
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also allow generic function types as type arguments.
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enabledIn: '2.14.0'
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expired: true
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set-literals:
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help: "Set Literals"
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enabledIn: '2.0.0'
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expired: true
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spread-collections:
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help: "Spread Collections"
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enabledIn: '2.0.0'
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expired: true
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triple-shift:
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help: "Triple-shift operator"
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enabledIn: '2.14.0'
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validation: |
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class A {
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operator>>>(int k) => 42;
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}
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void main() {
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if ((A() >>> 1) == 42) print('feature enabled');
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}
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expired: true
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constructor-tearoffs:
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help: "Allow constructor tear-offs and explicit generic instantiations."
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enabledIn: '2.15.0'
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validation: |
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class A {
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A() {
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print('feature enabled');
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}
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}
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void main() {
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var c = A.new;
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c();
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}
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expired: true
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enhanced-enums:
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help: "Enhanced Enums"
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enabledIn: '2.17.0'
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validation: |
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enum T {
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t();
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void test() {
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print('feature enabled');
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}
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}
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void main() {
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T.t.test();
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}
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expired: true
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named-arguments-anywhere:
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help: "Named Arguments Anywhere"
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enabledIn: '2.17.0'
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validation: |
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void test(String msg, {bool enabled : false}) {
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if (enabled) {
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print(msg);
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}
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}
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void main() {
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test(enabled : true, 'feature enabled');
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}
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expired: true
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super-parameters:
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help: "Super-Initializer Parameters"
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enabledIn: '2.17.0'
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validation: |
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class B {
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final String foo;
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B(this.foo);
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}
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class C extends B {
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C(super.foo);
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}
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void main(){
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print(C('feature enabled').foo);
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}
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expired: true
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inference-update-1:
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help: "Horizontal type inference for function expressions passed to generic invocations."
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enabledIn: '2.18.0'
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validation: |
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void test(List<int> list) {
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var a = list.fold(0, (x, y) => x + y);
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f(a);
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}
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void f<T>(T t) {
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if (T == int) {
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print('feature enabled');
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}
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}
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void main() {
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test([1, 2, 3]);
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}
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