microsoft
Add `__brand` to make empty interfaces nominal
Because who have thought that there are so many existing empty interfaces which are also used as parameter types. And thus this follows the pattern in https://www.typescriptlang.org/play/?#example/nominal-typing.
Preparing for #2074.
Thanks for the PR!
This section of the codebase is owned by @saschanaz - if they write a comment saying "LGTM" then it will be merged.
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https://github.com/microsoft/TypeScript-DOM-lib-generator/pull/1246/files#r881972594 suggested emitting a class with a private member. While I'm all for emitting classes (yes please) but a private member would only raise the possibility to clash with other libraries. Introducing a public member would allow other libraries to match the brand.
These will end up being in completions and so on (I see people do like " brand": any to derank them); is this a pattern taken from the existing trusted types definition or something?
I don't know that we actually use type branding in any of the existing lib.d.ts files, so this would be a new thing I think.
These will end up being in completions and so on
This is only for empty interfaces so I think that part is less a problem, although putting a space is an interesting solution.
is this a pattern taken from the existing trusted types definition or something?
https://www.typescriptlang.org/play/?#example/nominal-typing
As you saw in #2074 the most popular one (I don't think there's any other comparable library?) uses private brand: true 😞
One thing I think we're going to have to try is to port this code into the main TS repo and run the extended suite.
Perhaps a better approach would be to implement https://webidl.spec.whatwg.org/#ref-for-dfn-class-string, ie. resurrect the spirit of #1762 et al.?
This could only really be a TS 6.0+ change (for all lib targets to include es6's well-known symbols) but it seems better than introducing ghost properties across the entire library.
