Tuple should be readonly by default

Any tuples can mutate, this entails incorrect typing

TypeScript Version: 4.1.0-dev.20200828

Search Terms:
"readonly tuple"
"immutable tuple"

Code

const exampleSort: [number, string] = [2, '1'];

exampleSort.sort();

exampleSort // Type: [number, string], RealType: [string, number]

const exampleSplice: [number, string] = [2, '1'];

exampleSplice.splice(0, 1);

exampleSplice // Type: [number, string], RealType: [string]

Expected behavior:

const exampleSort: [number, string] = [2, '1'];

// Property 'sort' does not exist on type '[number, string]'.(2339)
exampleSort.sort();

const exampleSplice: [number, string] = [2, '1'];

// Property 'splice' does not exist on type '[number, string]'.(2339)
exampleSplice.splice(0, 1);

Actual behavior:

const exampleSort: [number, string] = [2, '1'];

exampleSort.sort();

const exampleSplice: [number, string] = [2, '1'];

exampleSplice.splice(0, 1);

Playground Link: https://www.typescriptlang.org/play?ts=4.1.0-dev.20200828#code/MYewdgzgLgBApgDwIYFsAOAbOBlEAnKALhgG0wBXFAIzjwBoZo8BLMAcwF0YBeUgJgYByAIyCOAbgBQkxKkw58UAHQRFACgCUUmcnRZcBGAHojMACoBPNHGJlKNeoygt2HBgCU4SDJeu2mrGwMFNS0HNKgkLCyejiYzMA2pCEODAGuPPxCohLSMfLY8YkqRXBqAAwMwlp5ugWlxqa+SXahjumcHl4+Vi0d4dKSQA

Related Issues:

Inizia riproducendo gli esempi di tuple nel TypeScript Playground collegato e confronta i tipi riportati con le mutazioni a runtime di sort e splice. Traccia il modo in cui il compilatore gestisce la mutabilità di tuple e array; il lavoro è completo quando per queste operazioni vengono visualizzati i diagnostici attesi senza compromettere l’uso valido delle tuple.