Completion does not work for generic type extending tuple or array of all partial type

[ishowta]

Bug Report

🔎 Search Terms

auto completion, suggestion, tuple, array, mapped types

🕗 Version & Regression Information

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

⏯ Playground Link

Playground link with relevant code

💻 Code

// It doesn't work

type BaseTheme = {
 component?: string
}

declare function extendTheme<
 Extensions extends [BaseTheme & Record<string, unknown>]
>(extensions: Extensions): void

extendTheme([{
 /* Can't autocomplete here */
}])



// list also doesn't work

type BaseTheme2 = {
 component?: string
}

declare function extendTheme2<
 Extensions extends (BaseTheme2 & Record<string, unknown>)[]
>(extensions: Extensions): void

extendTheme2([{
 /* Can't autocomplete here */
}])



// with required field works

type BaseTheme3 = {
 component?: string
 requiredField: string
}

declare function extendTheme3<
 Extensions extends [BaseTheme3 & Record<string, unknown>]
>(extensions: Extensions): void

extendTheme3([{
 /* Can autocomplete here */
}])



// but with required field and complete required field doesn't work

type BaseTheme4 = {
 component?: string
 requiredField: string
}

declare function extendTheme4<
 Extensions extends [BaseTheme4 & Record<string, unknown>]
>(extensions: Extensions): Extensions

extendTheme4([{
 requiredField: 'foo',
 /* Can't autocomplete here */
}])

// also BaseTheme with no mapped types doesn't work too

declare function extendTheme4WithNoMapped<
 Extensions extends [BaseTheme4]
>(extensions: Extensions): Extensions

extendTheme4WithNoMapped([{
 requiredField: 'foo',
 /* Can't autocomplete here */
}])



// no extend tuple works

type BaseTheme5 = {
 component?: string
}

declare function extendTheme5<
 Extensions extends BaseTheme5
>(extensions: [Extensions]): Extensions

extendTheme5([{
 /* Can autocomplete here */
}])

🙁 Actual behavior

No autocomplete

🙂 Expected behavior

Autocomplete

[andrewbranch]

Probably related to #33937

[ishowta]

Sorry, the mapped type was not relevant to this problem, so I removed it to simplify problem. (BaseTheme & Record<string, unknown => BaseTheme)

edit: Some patterns did not work without the mapped type, but others did.

[RyanCavanaugh]

Closing language service bugs related to the 6.0 implementation. For more information, see #62827