dart analyzer doesn't invalidate .dartServer cache

[aam]

dart->flutter roller failed once flutter/flutter#179502, then succeeded on the next roll seemingly without any actual fixes landing.

When troubleshooting this locally, I saw reported analyzer finding

/p/f/f1/flutter/packages/flutter  $ ~/p/f/f1/flutter/bin/flutter analyze  
Analyzing flutter...                                                    

warning • A value for optional parameter 'name' isn't ever given • lib/src/widgets/widget_inspector.dart:1:1 • unused_element_parameter

which only disappeared after I removed ~/.dartServer (moved it so I can restore it later).

The error came back after I restored ~/.dartServer.

This seems to point out to some change that landed in dart sdk https://dart.googlesource.com/sdk.git/+log/42fe3327abca..34287942e687

2025-12-05 [dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com](mailto:dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com) Version 3.11.0-210.0.dev
2025-12-04 [dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com](mailto:dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com) Version 3.11.0-209.0.dev

that didn't have provisions to invalidate analysis server cache properly.

cc @stereotype441 @scheglov

[scheglov]

The analyzer caches analysis results, such as diagnostics for files. The key for the cache is roughly based on the content of the Dart files, and the DATA_VERSION constant in the analyzer. We increment DATA_VERSION every time when we change the format for any cached result. But we usually don't increment when we do logical changes, like changing when some diagnostic is reported. This might lead to diagnostics that are seemingly reported by DAS, but disappear when you open the file in the IDE, because than the analyzer will need full resolved AST, and so recompute diagnostics too. For dart analyze or flutter analyze, because they don't request resolved ASTs, the diagnostics might then stick until the cache is removed, or DATA_VERSION incremented by other reasons.

[aam]

thanks @scheglov , perhaps DATA_VERSION should be more eagerly incremented as current behavior results in significant amount of developer's time wasted(like chasing dart->flutter failed rolls).

[FMorschel]

Could this be related to #62012?