[NewErrors] 4.3.0-dev.20210228 vs 4.2.2

[typescript-bot]

The following errors were reported by 4.3.0-dev.20210228, but not by 4.2.2

cdr/code-server

9 of 47 projects failed to build with the old tsc

lib/vscode/extensions/html-language-features/server/tsconfig.json

• error TS2367: This condition will always return 'true' since the types 'Promise<import("/mnt/ts_downloads/code-server/lib/vscode/extensions/node_modules/typescript/lib/typescript").LanguageService>' and 'false' have no overlap.
  • lib/vscode/extensions/html-language-features/server/src/modes/javascriptMode.ts#L68

lib/vscode/extensions/typescript-language-features/tsconfig.json

• error TS2367: This condition will always return 'true' since the types 'Promise<import("/mnt/ts_downloads/code-server/lib/vscode/extensions/typescript-language-features/src/typescriptService").ServerResponse.Response<protocol.Response>>' and 'false' have no overlap.
  • lib/vscode/extensions/typescript-language-features/src/tsServer/server.ts#L362

ReactiveX/rxjs

7 of 11 projects failed to build with the old tsc

src/tsconfig.cjs.spec.json

• error TS2769: No overload matches this call.
  • src/internal/operators/zipWith.ts#L81

src/tsconfig.esm5.rollup.json

• error TS2769: No overload matches this call.
  • src/internal/operators/zipWith.ts#L81

typeorm/typeorm

tsconfig.json

• error TS2367: This condition will always return 'true' since the types 'Promise<any>' and 'false' have no overlap.
  • src/driver/aurora-data-api-pg/AuroraDataApiPostgresQueryRunner.ts#L71
  • src/driver/cockroachdb/CockroachQueryRunner.ts#L89
  • src/driver/mysql/MysqlQueryRunner.ts#L75
  • src/driver/oracle/OracleQueryRunner.ts#L73
  • src/driver/postgres/PostgresQueryRunner.ts#L79

reduxjs/redux-devtools

17 of 51 projects failed to build with the old tsc

packages/redux-devtools/tsconfig.json

• error TS2322: Type 'MonitorProps' is not assignable to type 'IntrinsicAttributes & Omit<any, "monitorState" | "nextActionId" | "actionsById" | "stagedActionIds" | "skippedActionIds" | "committedState" | "currentStateIndex" | "computedStates" | "isLocked" | "isPaused" | "dispatch">'.
  • packages/redux-devtools/src/createDevTools.tsx#L127
  • packages/redux-devtools/src/createDevTools.tsx#L155
• error TS2322: Type 'MonitorProps & { store: LiftedStore<S, A, MonitorState>; }' is not assignable to type 'IntrinsicAttributes & Omit<any, "monitorState" | "nextActionId" | "actionsById" | "stagedActionIds" | "skippedActionIds" | "committedState" | "currentStateIndex" | "computedStates" | "isLocked" | "isPaused" | "dispatch">'.
  • packages/redux-devtools/src/createDevTools.tsx#L167

[DanielRosenwasser]

I think the Redux changes might have been caused by #42819. I think the hint for me is the Omit<any, ...>. (@weswigham)

The new "sufficiently overlaps" error is very confusing, but is expected fallout from #25330. I really wish we had discussed this at a design meeting since it's a potentially disruptive breaking change. In some of the examples above, we're seeing undesirable behavior due to strictPropertyInitialization being off. I guess testing a this.func and not calling it is always suspicious regardless of strictPropertyInitialization, so maybe that's why we never hit a similar issue with uncalled function checks. (@elibarzilay, @RyanCavanaugh)

[weswigham]

@DanielRosenwasser I've tracked down the change that broke redux-devtools, and it's not that one; it's df5ffc0 . Omit<any, Whatever> is just an alias for {[index:string]: any; [index:number]: any}; the comparison in the error apparently only worked by virtue of the number index signature assignability rule that got removed. MonitorProps doesn't have an index signature, so it fails now.

[RyanCavanaugh]

@DanielRosenwasser Wes and I spoke and recommend that we keep the assignability-target rule in place when the target has both string and numeric index signatures

[DanielRosenwasser]

Thanks for investigating! Let me look into it quickly.