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dart / monorepo / / 2e1fea536edf2f70e6270a6e8eaf8c6cbc99a3b0
commit2e1fea536edf2f70e6270a6e8eaf8c6cbc99a3b0[log] [tgz]
authorSrujan Gaddam <srujzs@google.com>Mon Jul 07 12:50:25 2025 -0700
committerdart-internal-monorepo <dart-internal-monorepo@dart-ci-internal.iam.gserviceaccount.com>Mon Jul 07 12:52:10 2025 -0700
tree9441b763323aad652511aa3ce240cbdf845eb242
parent26eeb0f0d14846a3337045464061264cf39caf82 [diff]
[dart2js/ddc/dart2wasm/dart:js_interop] Support SharedArrayBuffers in JS typed data wrappers

https://github.com/dart-lang/sdk/issues/56455

The existing native typed data implementation in dart2js/ddc
and the JS typed data wrappers in dart2wasm do not support
SharedArrayBuffers.

In dart2js/ddc, this is because the native type for ByteBuffer
is simply ArrayBuffer, leading to type failures when using
SharedArrayBuffers. To handle this, this change makes NativeByteBuffer
an abstract parent class to NativeArrayBuffer and NativeSharedArrayBuffer.
This allows ByteBuffer to support both types. There is a preexisting
SharedArrayBuffer type in dart:html that we should avoid breaking, so
we add an interface that NativeSharedArrayBuffer implements and expose
that interface.

In dart2wasm, JSArrayBufferImpl only allows ArrayBuffers as its
extern ref. This change makes that wrapper support SharedArrayBuffers
as well.

In dart:js_interop, the existing toJS conversion on ByteBuffer
now throws if the underlying buffer was actually a SharedArrayBuffer.
This is to support the return type of JSArrayBuffer. This behavior
technically already existed due to type differences in the JS
compilers, but was never possible with dart2wasm.

CoreLibraryReviewExempt: Backend-specific libraries with no real functional changes to public APIs.
Change-Id: I4dac9fb808590bf0c274da815c152cd4637316b1
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/437526
Reviewed-by: Stephen Adams <sra@google.com>
Commit-Queue: Srujan Gaddam <srujzs@google.com>

https://dart.googlesource.com/sdk/+/67bda7c22b16254819345420cb293cc5ef58c4bf
2 files changed
tree: 9441b763323aad652511aa3ce240cbdf845eb242
  1. engine/
  2. tools/
  3. .gitignore
  4. commits.json
  5. DEPS
  6. OWNERS
  7. README.md
README.md

Monorepo

A gclient solution for checking out Dart and Flutter source trees

Monorepo is:

  • Optimized for Tip-of-Tree testing: The Monorepo DEPS used to check out Dart and Flutter dependencies comes from the Flutter engine DEPS with updated dependencies from Dart.

Checking out Monorepo

With depot_tools installed and on your path, create a directory for your monorepo checkout and run these commands to create a gclient solution in that directory:

mkdir monorepo
cd monorepo
gclient config --unmanaged https://dart.googlesource.com/monorepo
gclient sync -D

This gives you a checkout in the monorepo directory that contains:

monorepo/
  DEPS - the DEPS used for this gclient checkout
  commits.json - the pinned commits for Dart, flutter/engine,
                 and flutter/flutter
  tools/ - scripts used to create monorepo DEPS
engine/src/ - the flutter/buildroot repo
    flutter/ - the flutter/engine repo
    out/ - the build directory, where Flutter engine builds are created
    third_party/ - Flutter dependencies checked out by DEPS
      dart/ - the Dart SDK checkout.
        third_party - Dart dependencies, also used by Flutter
flutter/ - the flutter/flutter repo

Building Flutter engine

Flutter's instructions for building the engine are at Compiling the engine

They can be followed closely, with a few changes:

  • Googlers working on Dart do not need to switch to Fuchsia's Goma RBE, except for Windows. The GOMA_DIR enviroment variable can just point to the .cipd_bin directory in a depot_tools installation, and just goma_ctl ensure_start is sufficient.
  • The --no-prebuilt-dart-sdk option has to be added to every gn command, so that the build is set up to build and use a local Dart SDK.
  • The --full-dart-sdk option must be added to gn for the host build target if you will be building web or desktop apps.

Example build commands that work on linux:

MONOREPO_PATH=$PWD
if [[ ! $PATH =~ (^|:)$MONOREPO_PATH/flutter/bin(:|$) ]]; then
  PATH=$MONOREPO_PATH/flutter/bin:$PATH
fi

export GOMA_DIR=$(dirname $(command -v gclient))/.cipd_bin
goma_ctl ensure_start

pushd engine/src
flutter/tools/gn --goma --no-prebuilt-dart-sdk --unoptimized --full-dart-sdk
autoninja -C out/host_debug_unopt
popd

Building Flutter apps

The Flutter commands used to build and run apps will use the locally built Flutter engine and Dart SDK, instead of the one downloaded by the Flutter tool, if the --local-engine option is provided.

For example, to build and run the Flutter spinning square sample on the web platform,

MONOREPO_PATH=$PWD
cd flutter/examples/layers
flutter --local-engine=host_debug_unopt \
  -d chrome run widgets/spinning_square.dart
cd $MONOREPO_PATH

To build for desktop, specify the desktop platform device in flutter run as -d macos or -d linux or -d windows. You may also need to run the command

flutter create --platforms=windows,macos,linux

on existing apps, such as sample apps. New apps created with flutter create already include these support files. Details of desktop support are at Desktop Support for Flutter

Testing

Tests in the Flutter source tree can be run with the flutter test command, run in the directory of a package containing tests. For example:

MONOREPO_PATH=$PWD
cd flutter/packages/flutter
flutter test --local-engine=host_debug_unopt
cd $MONOREPO_PATH

Troubleshooting

Please file an issue or email the dart-engprod team with any problems with or questions about using monorepo.

We will update this documentation to address them.

  • flutter commands may download the engine and Dart SDK files for the configured channel, even though they will be using the local engine and its SDK.

Windows

  • On Windows, gclient sync needs to be run in an administrator session, because some installed dependencies create symlinks.