Extensions don't trigger library import for their names only

[FMorschel]

Repro:

extension.dart

extension Ext on int {}

main.dart:

/// This is a dart doc for [f] that uses an [Ext] type.
void f<E extends Ext>() {}

Neither Ext will trigger the quick-fix for the importing of extension.dart. If you add a line Ext; inside f it does.

I volunteer to help with this.

[FMorschel]

Here is the CL https://dart-review.googlesource.com/c/sdk/+/401040

[FMorschel]

This still makes one test fail. I'm on my lunch break now, when I get to my computer I'll add a comment on the CL asking for what I should do in that case.

[bwilkerson]

Note that the use of Ext in void f<E extends Ext>() {} is invalid because Ext isn't a type.

I can see wanting this behavior for the doc comment case, though, but for that case it should probably create a doc-import.

@srawlins

[FMorschel]

Yeah, I noticed later. I originally detected this by making a doc. Thanks!

[FMorschel]

Currently the LinterLintCode.comment_references calls on ImportLibrary, which adds a normal import.

Adding a call for the forExtension constructor along with forType solves this but doesn't address your point of it being a doc-import. I can probably make this change with more time, but I'd make this CL only about fixing this and creating a new issue/CL for migrating those fixes for this.

Unfortunately, this is only accessible if that lint is enabled and it is off by default. Why is that? I'd expect more care for the docs from everyone and this being on would help with that.

[FMorschel]

Updated this CL to the above.

[bwilkerson]

Unfortunately, this is only accessible if that lint is enabled and it is off by default. Why is that?

One reason is because the lint was written before there were doc imports. If we required users to add a normal import for every reference in a doc comment then the dependency graph would have far more edges than necessary in order to run the program, and that isn't good for users.

As I said elsewhere, we need to look at the lints/warnings for doc imports from a holistic perspective and figure out what the right UX is. It's possible that we'll convert the lint into a warning now that we have doc imports.