[dart2js] Annotation for exception stacks with shorter prefix
Dart's `throw` expression does not correspond exactly to JavaScript's `throw` statement. To implement Dart semantics, and to reduce code size, dart2js uses the functions `wrapException` and `throwExpression` from the dart2js runtime. As a result, these functions appear in the stack trace (one or both).
A consequence of this is that a fixed prefix of an error stack is less useful, as potentially interesting frames are forced out of the prefix by these 'noise' frames.
This change ensures only one of the helpers on the stack trace.
It is also possible to get rid of the helper frame by an annotation.
The annotation `@pragma('dart2js:stack-starts-at-throw')` causes the stack to be captured in the current JavaScript function rather than in a helper. The cost is more code at the call site, about 12 bytes per `throw` expression in minified code. The annotation can be placed on a method, class or library, and applies to all `throw` expression in the scope of the annotated element.
This change uses the annotation to remove noise frames from type errors and some other errors in the runtime.
Change-Id: If15184a5963fb054199177bb4526b32f25e53fe9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/406684
Reviewed-by: Mayank Patke <fishythefish@google.com>
Reviewed-by: Nate Biggs <natebiggs@google.com>
https://dart.googlesource.com/sdk/+/a11aeeb5007bb118e49c60ff84c6edbfab4232a4
Monorepo is:
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
Flutter's instructions for building the engine are at Compiling the engine
They can be followed closely, with a few changes:
goma_ctl ensure_start is sufficient.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 $(command -v gclient))/.cipd_bin goma_ctl ensure_start pushd engine/src flutter/tools/gn --goma --no-prebuilt-dart-sdk --unoptimized --full-dart-sdk autoninja -C out/host_debug_unopt popd
The Flutter commands used to build and run apps will use the locally built Flutter engine and Dart SDK, instead of the one downloaded by the Flutter tool, if the --local-engine option is provided.
For example, to build and run the Flutter spinning square sample on the web platform,
MONOREPO_PATH=$PWD cd flutter/examples/layers flutter --local-engine=host_debug_unopt \ -d chrome run widgets/spinning_square.dart cd $MONOREPO_PATH
To build for desktop, specify the desktop platform device in flutter run as -d macos or -d linux or -d windows. You may also need to run the command
flutter create --platforms=windows,macos,linux
on existing apps, such as sample apps. New apps created with flutter create already include these support files. Details of desktop support are at Desktop Support for Flutter
Tests in the Flutter source tree can be run with the flutter test command, run in the directory of a package containing tests. For example:
MONOREPO_PATH=$PWD cd flutter/packages/flutter flutter test --local-engine=host_debug_unopt cd $MONOREPO_PATH
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.gclient sync needs to be run in an administrator session, because some installed dependencies create symlinks.