consider nonfunction type alias support in `avoid_private_typedef_functions`

[pq]

As per the discussion in dart-archive/linter#2534, it's not obvious whether avoid_private_typedef_functions should be expanded to support nonfunction type aliases.

Specifically cases like:

typedef _T = Object; // LINT?
mixin M { }
class _C = Object with M; // LINT?

/cc @davidmorgan @Hixie @goderbauer

[Hixie]

I don't really see the value in avoid_private_typedef_functions at all, so... :-)
(I see the value in #58350, and it would apply to non-function type aliases, yes.)

[eernstg]

The documentation seems to imply that the motivation for avoid_private_typedef_functions was to encourage the use of inline function types:

AVOID private typedef functions used only once. Prefer inline function syntax.

The reference to private is probably there because it is possible to determine modularly that a given type alias is used only once when it's private, but for a non-private type alias there could always be additional usages that we don't know about.

So the single-use type alias would be written by a person who hasn't yet heard about inline function types. Aren't such persons rare today?

Also, it doesn't really apply to the non-function type aliases (because they denote types that we've always been able to write inline).

All in all, I don't think there's a lot of value in having this lint today.

[pq]

Fantastic. Thanks a million for the thoughtful feedback. I'll consider this one "considered" and close it out.

Much appreciated!