Keep operator== parameter type as Object

[srawlins]

Fixes #1016

[rrousselGit]

I appreciate the PR, but I don't fully understand the problem.

What are we really solving here? Performance?

[srawlins]

No, there shouldn't be any performance implications.

These operator == overrides explicitly expand the parameter type from Object to dynamic. Why?

No Dart runtime passes a null value to an override == implementation. Explicitly expanding the parameter type does not seem to serve a purpose, and can lead to confusion that the function will ever see a null argument value.

When someone knows that Object.== takes an Object, and that one of these classes has expanded the parameter type to be dynamic, they may question why, and look for the important reason that the type has been changed. But it's a red herring; there is no reason. If one of these implementations did something with a null argument value, like:

bool operator ==(dynamic other) {
  if (other == null) print('boo');
  return ...
}

it would be surprising that the code never prints 'boo'. The only effect that expanding the parameter type to dynamic seems to have is confusion.

[rrousselGit]

I was thinking that this could be useful in cases someone wants to override == by hand.
But it looks like from the interface POV, == isn't overridden, so it doesn't block them.

So this looks to be purely syntactic. Which I don't think adds a lot of value for generated code.

I'll merge it anyway, but if what triggered this PR is a lint rule, chances are that lint rule shouldn't trigger on generated files.
Users generally shouldn't read its source. Stylistic choices there shouldn't matter.

[srawlins]

Thank you! ❤️