Kate Lovett 460d55e659
Bump Dart to 3.9 (#179041)
Prep for https://github.com/flutter/flutter/issues/178827

This bumps Dart to 3.9.

We are holding off on 3.10 until we can include best practices for dot
shorthands in the style guide, which will follow the lint update in
#178827

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

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on [Discord].

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<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
2025-11-25 00:41:40 +00:00
..
2025-11-25 00:41:40 +00:00

flutter/third_party

This directory contains third-party code that is a combination of:

  • Code that is vendored into the Flutter repository, from an external source. For example, we might have third_party/glfw, which contains the GLFW library, vendored from an external repository.

    💡 TIP: See DEPS for where these sources are declared.

  • Code that originates from another repository, but is copied (sometimes with alterations) into the Flutter repository. For an example, see third_party/spring_animation.

  • Code that is licensed separately from the rest of the Flutter repository. For example, see third_party/txt.

When adding a new externally sourced third-party library, update .gitignore:

# Ignores all third_party/ directories except for the ones we want to track.

+ !{folder_name}/