Request for lint: unnecessary_dynamic

[davidmorgan]

How about a lint that fires when you write dynamic for a parameter type but Object would have worked?

e.g.

void foo(dynamic bar) {
  if (bar is String) {
    ...
  } else if (bar is int) {
    ...
  } else throw UnsupportedError();
}

I see this pretty frequently and I think it hides a misunderstanding about what dynamic is useful for, i.e. for the rare cases when you want to turn off static checking and always do dynamic dispatch.

Happy to take a shot at implementing this if you think it makes sense, particularly if you can give hints about how to figure out whether dynamic dispatch was used :)

Thanks!

[bwilkerson]

@leafpetersen @srawlins
I know that we were, at one point, looking to define a coherent set of options related to uses of dynamic, but I don't know whether this would have been covered or what the current status of that work is. Is that still planned?

Should something like this be implemented as a lint, or would it be covered by the mechanisms above?