[all] Omit obvious local types

[stuartmorgan-g]

Makes the analysis options changes described in flutter/flutter#178827:

• Adding omit_obvious_local_variable_types
• Adding specify_nonobvious_local_variable_types
• Adding specify_nonobvious_property_types
• Adding type_annotate_public_apis
• Removing always_specify_types

After those changes, makes the following repo-wide changes:

• dart fix --apply in all packages and in script/tool/
• dart format in all packages and in script/tool/
• update-excerpts repo tooling command to update excerpts based on the changes to their sources

Also updates the min Flutter/Dart SDK version to 3.35/3.9 for the following packages, to avoid analyze failures in the N-2 legacy analysis run due to what appears to be a 3.9 change in what the Dart analyzer continues to be an obvious local type in loop iterations:

• go_router
• google_fonts
• google_identity_services_web
• google_maps_flutter_web
• local_auth_platform_interface
• metrics_center
• multicast_dns
• pigeon
• rfw
• shared_preferences
• two_dimensional_scrollables
• vector_graphics_compiler
• mustache_template
• path_parsing

Because this is causing a significant amount of format churn already, I took this opportunity to update the repository tooling to a min Dart SDK of 3.8 (the N-2 stable version, so the earliest version we need the tooling to support) to pick up the new format style, so the amount of automated formatter change is higher in script/tool/ than in the packages.

This does contain two manual changes (other than the repo tooling min version):

• d700b45 changes dynamic to Object? in a few places where dynamic caused analyzer warnings under the new rule set.
• Updates the repo tooling to ignore .dart_tool/ when looking for unexpected local analysis_options.yaml files, to fix issues running the repo tool's analyze command locally based on recent changes in dart behavior.

This does not include any CHANGELOG or version updates; even though we normally version any changes to production code, mass automated changes like this aren't worth the churn of releasing. This includes changes to lib/example/main.dart and to README.md excerpts; while the style changes will be user-visible on pub.dev, it's fine for those changes to wait for the next release of each package.

Part of flutter/flutter#178827

[stuartmorgan-g]

@tarrinneal or @bparrishMines please review the non-automated commits (3620b2c, f231a2f, d700b45).

Everyone else, please feel free to ignore this PR.

[gemini-code-assist]

Code Review

This pull request introduces new linter rules to prefer type inference for obvious local variables and then applies these changes across the entire repository. The changes are extensive but mostly automated, resulting in more concise code by removing explicit type annotations where they are redundant. The modifications to analysis_options.yaml are correct and the subsequent code fixes align with the new linting rules. Overall, this is a solid stylistic improvement for the codebase.

[chunhtai]

LGTM for go_router and go_router_builder part

[stuartmorgan-g]

Hm, that's unfortunate. From the analyze_legacy N-2 failures it appears that what the analyzer considers a non-obvious local in the context of a list iteration changed in Dart 3.9. I'm going to update all the affected packages to a min of Dart 3.9 to avoid the issue.

[Piinks]

Hm, that's unfortunate. From the analyze_legacy N-2 failures it appears that what the analyzer considers a non-obvious local in the context of a list iteration changed in Dart 3.9. I'm going to update all the affected packages to a min of Dart 3.9 to avoid the issue.

Ah good to know! I will bump the framework too, I think it is still on 3.8

[Piinks]

.. or 3.10. We're headed that way to adopt dot shorthands in the framework. Checking in with @loic-sharma

[stuartmorgan-g]

Ah good to know! I will bump the framework too, I think it is still on 3.8

I would not expect this issue to affect anything in the framework tree; it's specific to the fact that we run analyze with Flutter master, stable, N-1 stable, and N-2 stable. Presumably flutter/flutter is only running analyze with its own current version of dart.

[Piinks]

Ok. Touched base with Loïc, we want to publish guidelines/style guide for use of dot shorthands, so we won't bump to 3.10 until we have been able to finalize and communicate those.

[parlough]

package:mustache_template changes look good to me! Thanks :D

[Piinks]

Oh so nice! 👏

[Piinks]

LGTM

[stuartmorgan-g]

Since there's a window of opportunity here where everything passed without any other PRs landing (and since unlike flutter/flutter we don't have a way to close the flutter/packages tree manually), I'm going to seize the moment and land this now rather than tomorrow.