prettier plugin: class with generic, extending namespaced base class, fails

[byCedric]

Bug Description

The flow-api-translator has been a blessing. Unfortunately, I ran into a bug specifically when:

• When using a generic in the class definition
• When extending a namespace class import

E.g.

// Input
import * as Test from 'test-lib'
class MyClass<T> extends Test.BaseClass {}
export default MyClass

This results in the following error:

/Users/cedric/.../node_modules/prettier/doc.js:931
              } else if (isConcat(doc) || doc.type === "fill") {
                                              ^

TypeError: Cannot read properties of undefined (reading 'type')
    at fits (/Users/cedric/.../node_modules/prettier/doc.js:931:47)
    at printDocToString (/Users/cedric/.../node_modules/prettier/doc.js:1073:44)
    at coreFormat (/Users/cedric/.../node_modules/prettier/index.js:8838:22)
    at formatWithCursor2 (/Users/cedric/.../node_modules/prettier/index.js:9021:18)
    at /Users/cedric/.../node_modules/prettier/index.js:38183:12
    at Object.format (/Users/cedric/.../node_modules/prettier/index.js:38197:12)
    at print (/Users/cedric/.../node_modules/hermes-transform/dist/transform/print.js:88:25)
    at translateFlowDefToTSDef (/Users/cedric/.../node_modules/flow-api-translator/dist/index.js:64:37)

Funny enough, using a named import actually works:

// Input
import { BaseClass } from 'test-lib'
class MyClass<T> extends BaseClass {}
export default MyClass

// Output
import { BaseClass } from "test-lib";
declare class MyClass<T> extends BaseClass {}
declare const $$EXPORT_DEFAULT_DECLARATION$$: typeof MyClass;
export default $$EXPORT_DEFAULT_DECLARATION$$;

Small side note, when using export default $$..$$ that is a typeof MyClass, the generic is wiped away. It would be nice if this could be written as just export default MyClass instead - it would retain the generic.

Used package versions:

• flow-api-translator@0.24.0
• prettier@2.8.8
• prettier-plugin-hermes-parser@0.24.0

Steps To Reproduce

1. npm i --save prettier@2.8.8 prettier-plugin-hermes-parser@0.24.0 flow-api-translator@0.24.0
2. Create test.js with:

const code = `
import * as Test from 'test-lib'
class MyClass<T> extends Test.BaseClass {}
export default MyClass
`

require('flow-api-translator')
  .translateFlowToTSDef(code, { parser: 'babel' })
  .then(console.log)

3. node ./test.js

The Expected Behavior

It converts the flow code to a typescript definition for named and namespace imports.