Incorrect inference/autocompletion on generic arrays, when values can be inferred from a defined object.

TypeScript Version: 4.1.2

Search Terms:
Autocompletion, incorrect, values, inference, generic, array, object, keys

Summary:
When an interface/a type has an object with generic keys, and an array of those keys, the array values cannot be infered from the object keys.

Code

interface Recipe<INGREDIENTS extends string> {
  quantities: Record<INGREDIENTS, number>
  allergens?: INGREDIENTS[]
}

function createRecipe<INGREDIENTS extends string>(recipe: Recipe<INGREDIENTS>) {}

createRecipe({
  quantities: {
    eggs: 1,
    flour: 2,
  },
  allergens: ['']
})

Expected behavior:
Here, when trying to give a value to allergens, the autocompletion should show "eggs" | "flour".

Actual behavior:
The autocompletion doesn't find anything.

Notes:
The other way is working: you can fill the array first, then the object keys will autocomplete - but this rarely make sense to write things that way.

Failed workarounds:
This bug is still present, even when:

• allergens is optionnal
• We switch from an interface to a type
• We use keyof this['quantities'] instead of INGREDIENTS[]

Commencez par reproduire l’exemple TypeScript 4.1.2 de l’issue, en vous concentrant sur l’inférence de l’objet quantities vers le tableau allergens et sur ses résultats d’autocomplétion. Comparez le comportement signalé avec l’ordre inverse, et considérez l’issue comme terminée lorsque "eggs" et "flour" sont proposés comme complétions pour allergens sans modifier les types génériques de l’exemple.