[vm/aot] Keep toString methods on exception classes in toString transformer

Flutter in google3 uses --delete-tostring-package-uri compiler option
to remove toString methods in package:flutter and dart:ui to reduce
size in release mode.
This has unfortunate effect of removing toString methods from exception
classes which may provide valuable information for investigating
problems seen in the wild.

This change adds a new @pragma('flutter:keep-to-string-in-subtypes')
on classes to keep toString methods on all subtypes of the annotated
classes. This pragma is now used on Exception and Error classes in


Issue: https://github.com/flutter/flutter/issues/61562
Change-Id: Ib739c83cdf6b539208f705ba198e63b8bc54fa61
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/227920
Reviewed-by: Dan Field <dnfield@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
7 files changed
tree: 1a67ac8e696b903d08482171ddd3124be68fd5a4
  1. .dart_tool/
  2. .github/
  3. benchmarks/
  4. build/
  5. docs/
  6. pkg/
  7. runtime/
  8. samples/
  9. samples-dev/
  10. samples_2/
  11. sdk/
  12. tests/
  13. third_party/
  14. tools/
  15. utils/
  16. .clang-format
  17. .gitattributes
  18. .gitconfig
  19. .gitignore
  20. .gn
  21. .mailmap
  22. .packages
  23. .style.yapf
  24. .vpython
  26. BUILD.gn
  27. CHANGELOG.md
  28. codereview.settings
  30. DEPS
  33. PRESUBMIT.py
  34. README.dart-sdk
  35. README.md
  36. sdk_args.gni
  37. SECURITY.md


A client-optimized language for fast apps on any platform

Dart is:

  • Optimized for UI: Develop with a programming language specialized around the needs of user interface creation.

  • Productive: Make changes iteratively: use hot reload to see the result instantly in your running app.

  • Fast on all platforms: Compile to ARM & x64 machine code for mobile, desktop, and backend. Or compile to JavaScript for the web.

Dart's flexible compiler technology lets you run Dart code in different ways, depending on your target platform and goals:

  • Dart Native: For programs targeting devices (mobile, desktop, server, and more), Dart Native includes both a Dart VM with JIT (just-in-time) compilation and an AOT (ahead-of-time) compiler for producing machine code.

  • Dart Web: For programs targeting the web, Dart Web includes both a development time compiler (dartdevc) and a production time compiler (dart2js).

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