Spreading one named tuple in another throws an error

[pushkine]

TS stable and nightly
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type T0 = [...[bar: string]] // = [bar: string]
type T1 = [foo: string, ...[bar: string]] // Error : Tuple members must all have names or all not have names. (5084)

[armanio123]

This is by design. Is a bit confusing but what's happening is that type T1 = [foo: string, ...[bar: string]] is an invalid syntax. Instead can label it and fix it by changing it as:

type T1 = [foo: string, ...args: [bar: string]]

There has been a design discussion some time ago about this. You can check more details here: #43744