Tuple + Record Intersection Assignment Compatibility Inconsistency

TypeScript Version: 4.1.0-dev.20200824

Search Terms: tuple, object, intersection, type, assignment, coercion

Code

Here is the type that I'd like to use in an assignment:

type X = {example: "Field"} & number[];

The following produces TS error 2322.

const x: X = {
  ...[1, 2],
  example: "Field",
} as const;

If we update this example like so, the type error disappears:

- const x: X = {
+ const x = {
    ...[1, 2],
    example: "Field",
  } as const;

+ const y: X = x;

Expected behavior:

I would have expected the first assignment to not produce a type error. I'm wondering if this inconsistency (if that's the correct word for it) is an edge case, or by design? Apologies if this issue is unhelpful! Thank you!

Actual behavior:

Playground Link: https://www.typescriptlang.org/play?#code/HYQwtgpgzgDiDGEAEAhATgewNYWEg3gLABQSSALgJ4zIAaSAvARAB7gwA2EAXEgEQAxAJYQOAEz4BfJADIkwAK5gARhDQBtALoBuEiTLwMwKOSQte9JkVJkkAOgfqAjABokAJk0v9t1uy68giLifN420iBQSIbG5LrEknrEoJCwCMgA6hhoWFHWZFQ0SJbMbGCcPPzCohLScooqalrxPjEmZowEPmQOds5unmG2SH7lAVXBEkNIEVFtcUkGRu2UFp0s8ZJAA

Inizia con il TypeScript Playground collegato e riproduci le due forme di assegnazione mostrate nell’issue. Segui il percorso di type-checking per i tipi intersezione, gli spread di array o tuple e le assegnazioni di letterali oggetto; il lavoro è concluso quando il comportamento è spiegato e, se viene confermato come bug, un test di regressione cattura il risultato atteso.