[import/no-unused-modules] Add an option to ignore typescript types

[demedos]

Hi, when using typescript it might be useful to add an option to ignore exported but unused types (including interfaces and enumerators) since it is common to export a component along with its props and let the consumer create derivative types for example.

This is something that has been implemented in ts-unused-exports via the allowUnusedEnums and allowUnusedTypes options.

Looking through the code I found out that typescript types are being handled already, see src/rules/no-unused-modules.js#L89.

[ljharb]

Is this something that @typescript-eslint/plugin might already cover?

[demedos]

Nope, there's nothing such as unused exports

[ciiqr]

Might be a bit more effort than just ignoring types entirely, but it would be cool if this could mark types referenced from used exports as used (ie. in the component/props example, the props type could be marked as used if the component itself is used). Might still want an option to enable this, though it seems like it would allow us to preserve some of the safety of this rule.

[silverwind]

I think adding a unusedTypeExports to no-unused-modules which defaults to true should be able to solve it, at least for me.

[silverwind]

#3011