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New behavior in v6 when interface extends two incompatible interfaces under exactOptionalPropertyTypesΒ #62569
Description
π Search Terms
Partial, @types/node, exactOptionalPropertyTypes, interface
π Version & Regression Information
- This changed between versions v5.9.3 and 6.0.0-dev.20251001
β― Playground Link
π» Code
namespace http {
export interface TcpSocketConnectOpts {
port: number;
}
export interface AgentOptions extends Partial<TcpSocketConnectOpts> {
keepAlive?: boolean | undefined;
}
}
namespace tls {
export interface ConnectionOptions {
port?: number | undefined;
}
}
interface AgentOptions extends http.AgentOptions, tls.ConnectionOptions {
maxCachedSessions?: number | undefined;
}π Actual behavior
This now fails to type checkβI believe correctly, because Partial<{ port: number }> is { port?: number }, not { port?: number | undefined }. Itβs surprising that this worked before.
π Expected behavior
Actually, the new behavior is expected, so probably @types/node needs an update. I wanted to flag this in case/for when other folks hit it!
Additional information about the issue
- Happens on latest
@types/node. - Discovered via True Mythβs nightly TS@next CI job as well as dependabot upgrades that test. The semver-ts.org guidance to test against upcoming versions is: good!
Activity
infra: temporarily disable `exactOptionalPropertyTypes`
Andarist commentedon Oct 9, 2025
bisects to #61683
jakebailey commentedon Oct 9, 2025
Probably this means we need to add yet another tsconfig variant to the node types to test this. But perhaps we should simply revert that PR...
Renegade334 commentedon Oct 9, 2025
I think we're better off just testing with exactOptionalPropertyTypes ubiquitously. We intend to be compatible with it, so is there any added value in testing without it as well?
jakebailey commentedon Oct 9, 2025
Probably not... (When it's not 4am for me I intend to hack dtslint to force this option on and see how bad things are in DT)
RyanCavanaugh commentedon Oct 9, 2025
Thanks for the report on this!
jakebailey commentedon Oct 9, 2025
Based on the label, we agree this is a bug in the types, yes? So DT has to be fixed?
RyanCavanaugh commentedon Oct 9, 2025
Yep
chriskrycho commentedon Oct 10, 2025
Confirmed resolved with
@types/node@24.7.1. Closing this accordingly. Thanks for hopping on it in the types so quickly Jake Bailey (@jakebailey) and for writing a test for it Mateusz BurzyΕski (@Andarist)! Appreciate you folks.