Empty rest parameter type inferred from candidate function with no rest parameters when "best match" contains a contextually typed argument

Bug Report

🔎 Search Terms

Rest parameter inference contextual

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about type inference

⏯ Playground Link

Playground link with relevant code

💻 Code

const doSomething = <Args extends unknown[]>(
    fn1: (aNumber: number, ...rest: Args) => void,
    fn2: (aNumber: number, ...rest: Args) => void,
) => {}

// OK, no contextual types
doSomething(
    (explicit: number, rest: string) => {}, // Args = [string]
    () => {},
)

// OK (both contain contextually typed arg)
doSomething(
    (contextual, rest: string) => {}, // Args = [string]
    (contextual) => {},
)

// Contextually type only fn1 - Not ok
doSomething(
    (contextual, rest: string) => {}, // ERROR
    () => {}, // Args = []
)
doSomething(
    (contextual, rest: string) => {}, // ERROR
    (explicit: number) => {}, // Args = []
)

🙁 Actual behavior

When fn1 (and only fn1) contains a contextually typed argument, it is ignored in favour of fn2

🙂 Expected behavior

In all of the examples, fn2 specifies no rest parameters at all.

I would expect functions that do not specify any rest parameters to always be the least preferable candidate (lowest weight?) for rest parameter inference, since "no rest parameters" can always be assigned to any rest parameter type.

Inizia con la riproduzione collegata in TypeScript Playground e riduci le tre chiamate a doSomething per isolare in che modo il contextual typing influisce sull'inferenza dei parametri rest. Segui il percorso di type-checking che seleziona i candidati per l'inferenza, quindi aggiungi un test di regressione per i casi mostrati; il lavoro è concluso quando il tipo rest [string] di fn1 non viene sostituito da [] di fn2.