This issue tracks migrations and work that is needed before shipping/flipping the flag.

• Migration on all the places where we are marking formal parameters as final. Missing fix for avoid_final_parameters #61812
• Migration on all formal parameters with no type annotation marked with the var keyword.

Context: #61525 (comment)

It used to be possible to mark formal parameters (in general, not just the ones in constructors) as final. This used to mean that the formal parameter itself was immutable. However, we decided that this feature should no longer be supported, which means that it will be an error to put final on a formal parameter of any function other than a declaring constructor

This does give rise to some inconveniences for developers who prefer to use immutable formal parameters (they're forced to change their code to not do that any more). However, final formal parameters are not common today, and it's not hard to teach dart fix to remove final in the locations where it is an error to have it.

• Make sure there's a migration path for the factory() breakages. [Primary Constructors] Warning for ambiguous factory method/factory constructor #61910
  • There seem to be none in g3.
• Prepare flutter/flutter repo for primary constructors. Add avoid_final_parameters lint and var_with_no_type_annotation