Fuzzy arrow / dynamic as bottom is a hint, but should be a warning

[mit-mit]

We stumbled over the grpc-dart repo not passing uses_dynamic_as_bottom by coincidence despite that repo running analysis on travis. The issue is that we currently report this as just a hint, which doesn't fail the build:

$ dartanalyzer lib test
Analyzing lib, test...
  hint • A function of type '(Socket) → void' can't be assigned to a variable of type '(dynamic) → FutureOr<void>' at lib/src/client/connection.dart:108:22 • uses_dynamic_as_bottom

Shouldn't this at least be a warning?

[mit-mit]

cc @leafpetersen

[vsmenon]

This will eventually become an error. Not sure it's worth making it a warning as an intermediate step.

[leafpetersen]

It might be worth making this a warning, if we can do so without breaking the internal builds (we're currently working on eliminating the hint internally). Making it a warning earlier might help us avoid accidental regressions. I'll look into it.

In the meantime if you want to protect against this, you can put the following in your analysis options file:

analyzer:
  errors:
    uses_dynamic_as_bottom: warning

[leafpetersen]

@srawlins if we promoted this from hint to warning, could we keep it from breaking builds internally?

[srawlins]

It won't break anything internally.

[leafpetersen]

I have a CL for this, but have to land a CL making our tests clean first. Mostly done, hoping to land today.

[leafpetersen]

CL here: https://dart-review.googlesource.com/c/sdk/+/34506