Typescript warnings about exports not found

[sirbrillig]

When starting Calypso, I get a ton of warnings like this that appear in the console:

WARNING in ./my-sites/checkout/composite-checkout/wpcom/types.ts 9:0-1022
"export 'WpcomStoreState' was not found in './types/wpcom-store-state'

It's weird because that type (and all the others mentioned) definitely exists. This doesn't appear to affect the actual running of code.

[sirbrillig]

I think it might be isolatedModules: webpack/webpack#7378 (comment)

Basically, when re-exporting types, you have to use export type and import type to comply with the rules of Typescript 3.8 (which we are using in Calypso).

However, doing so causes Prettier to throw an error because export type is not recognized until prettier 2.0.

So I think that right now we just have to have one error or another.

[ockham]

I think @sgomes is on this, see #41100.

[sgomes]

@ockham I am indeed. I had to close that PR to fix some @wordpress/* issues first (see #41141), but once that's sorted I'll go back to trying to update Babel.

[sirreal]

#41114 is upgrading to wp-prettier@2.

[sgomes]

The new Babel upgrade PR is at #41175.
This has now been merged.

[sgomes]

We may need some updates to eslint-plugin-import as well, so that import type { Foo } from './foo'; and import { makeFoo } from './foo'; can coexist in the same file without claiming there's a duplicate import.

Edit: See import-js/eslint-plugin-import#1667