ReadableStreamReadResult interface is private

[johnBartos]

Bug Report

🔎 Search Terms

ReadableStream, ReadableStreamReadResult

🕗 Version & Regression Information

• This changed between versions <= 4.1.5 and 4.2.x

⏯ Playground Link

Playground link with the bug (4.2.x)

Playground link without the bug (4.1.5)

💻 Code

        const handleChunk = ({ done, value }: ReadableStreamReadResult<Uint8Array>) => {
            console.log(done, value);
        }

🙁 Actual behavior

• Cannot find name 'ReadableStreamReadResult'.
• Return type of public method from exported class has or is using private name 'ReadableStreamReadResult'.

🙂 Expected behavior

No type error

[sandersn]

Looking at the PR microsoft/TypeScript-DOM-lib-generator#890, it looks like the name changed to ReadableStreamDefaultReadResult. Does that work for you @johnBartos?

[tchakabam]

@sandersn Not sure about @johnBartos ' case. But your above hint helped around here: Renaming the type occurence to ReadableStreamDefaultReadResult.

Am I correct in understanding this would actually be a breaking change from a minor version bump of tsc (a bug in that sense) ? This occured here as well from re-installing on a "typescript": "^4.1.5" package dev-deps (where probably 4.2.x got installed then).

EDIT: Just being curious checked the web spec status, which however is inline with this change in the type-name, see https://streams.spec.whatwg.org/#dictdef-readablestreamdefaultreadresult

However I don't understand why on a minor version bump the compiler doesn't provide a backward compatibility alias type here ... Even if you could deprecate the prior name somehow, adding a warning or so?

[MattiasBuelens]

First off all: I'm sorry for the inconvenience. I was the one who contributed this change to TypeScript 4.2.

In earlier versions of the Streams standard, many types didn't have "official" definitions with standardized names. So when I wrote these type definitions, I took a best-effort guess to name them based on what we had earlier in @types/whatwg-streams. When the Streams standard was finally updated with official WebIDL definitions for all types, some of these names didn't match my guess, hence I had to rename them.

Am I correct in understanding this would actually be a breaking change from a minor version bump of tsc (a bug in that sense) ? This occured here as well from re-installing on a "typescript": "^4.1.5" package dev-deps (where probably 4.2.x got installed then).

As far as I know, TypeScript doesn't follow semantic versioning. If you want to stay on the same minor version, you should use a tilde constraint like ~4.1.0 (example).

It's definitely not unusual for TypeScript to make breaking changes in the DOM types between minor releases. Pretty much every release notes article has a "lib.d.ts updates" section, giving a (non-exhaustive) list of changed types. The changes to the Streams types fit in that scheme.

[tchakabam]

@MattiasBuelens Thx for the context