Use string literal type in ArrayBuffer's Symbol.toStringTag

[petamoriken]

⚙ Compilation target

ES2023

⚙ Library

N/A

Missing / Incorrect Definition

For ES2023 or lower targets, it is acceptable to assign SharedArrayBuffer to an ArrayBuffer type. On the other hand, the reverse is not possible because Symbol.toStringTag of SharedArrayBuffer is a string literal type.

This problem can be solved by making Symbol.toStringTag of ArrayBuffer a string literal type. Set, Map, and Promise use the string type for library compatibility (#19006), while ArrayBuffer is not intended to be extended by the user, and indeed Symbol.species support for InitializeTypedArrayFromTypedArray has been removed (tc39/ecma262#2719), so there should be no problem.

This issue was reported by #59417 and has been addressed by making TypedArrays generic for the ES2024 target.

Sample Code

// ES2023 or lower targets, no type error
const buffer: ArrayBuffer = new SharedArrayBuffer(256);

Documentation Link

No response

[petamoriken]

FYI: Restricting subclassing support in built-in methods – Data (2024-10 TC39 meeting slide)

[milkcask]

Somewhat related: #60142
Same approach, using string instead of the exact well-known tags.

@petamoriken thanks for the FYI !