Fix createImportSpecifier with typescript 4.5+

[astegmaier]

↪️ Pull Request

This fixes #7325 and possibly also #7400. The issue, as @benpigchu pointed out here, was that Typescript 4.5 added support for type modifiers on specific import names. For example, it is now valid to write:

import { someFunc, type BaseType } from "./some-module.js";

Unfortunately, the way that the compiler API was changed to support this is not backward compatible :-(

Here's what the pre-4.5 API looked like:

createImportSpecifier(propertyName: Identifier | undefined, name: Identifier): ImportSpecifier;

And here's the new API (see PR):

createImportSpecifier(isTypeOnly: boolean, propertyName: Identifier | undefined, name: Identifier): ImportSpecifier;

Since there's no way that I know of to check a function's arity at runtime, I had to resort to a version check.

There were several other backward-incompatible changes in that PR (to updateImportSpecifier, createExportSpecifier and updateExportSpecifier), and I verified that we don't use these APIs in parcel.

💻 Examples

Without this change, when you have typescript 4.5+, @parcel/transformer-typescript-types will generate output like:

import { something as } from "./foo"

instead of

import { something } from "./foo

This change ensures that we do the right thing.

🚨 Test instructions

Several of the existing unit tests will break if you upgrade to typescript 4.5+ and don't apply this change, so it didn't seem necessary to add new ones.

I manually verified that with this change, and typescript 4.2.4 (the old version in the repo), all the unit tests still pass. You can test it yourself by modifying yarn.lock to revert back to 4.2.4, running yarn install, then yarn test:integration.

✔️ PR Todo

• Filled out test instructions (In case there aren't any unit tests)
• Included links to related issues/PRs

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[devongovett]

Wowwwwww... TS doesn't follow semver?? Maybe we should pin our dependency on it?

[mischnic]

The other side of that coin: #5978

[Jack-Works]

there's no way that I know of to check a function's arity at runtime

Yes you can

[mischnic]

Though that would break if Typescript implemented createImportSpecifier using something like createImportSpecifier(...args) in the future.