Infer non-narrowing predicates when the contextual signature is a type predicate by Andarist · Pull Request #60834 · microsoft/TypeScript

Andarist · 2024-12-20T23:03:05Z

addresses the concerns raised in the comments in #60741

typescript-bot · 2024-12-20T23:03:10Z

This PR doesn't have any linked issues. Please open an issue that references this PR. From there we can discuss and prioritise.

…e predicate

RyanCavanaugh · 2025-01-03T22:36:36Z

@typescript-bot test it

typescript-bot · 2025-01-03T22:36:40Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`test top400`	✅ Started	👀 Results
`user test this`	✅ Started	👀 Results
`run dt`	✅ Started	👀 Results
`perf test this faster`	✅ Started	👀 Results

typescript-bot · 2025-01-03T22:58:26Z

@RyanCavanaugh Here are the results of running the user tests with tsc comparing main and refs/pull/60834/merge:

Something interesting changed - please have a look.

Details

effect

tsconfig.json

[MISSING] error TS7016: Could not find a declaration file for module 'effect/Array'. '/mnt/ts_downloads/_/m/effect/packages/effect/src/Array.js' implicitly has an 'any' type.
[MISSING] error TS7016: Could not find a declaration file for module 'effect/Either'. '/mnt/ts_downloads/_/m/effect/packages/effect/src/Either.js' implicitly has an 'any' type.

typescript-bot · 2025-01-03T22:58:27Z

@RyanCavanaugh Here are some more interesting changes from running the user tests suite

Details

fp-ts

tsconfig.eslint.json

[MISSING] error TS2578: Unused '@ts-expect-error' directive.
[MISSING] error TS2345: Argument of type '(ma: ReaderTask<R2, number>) => ReaderTask<R2, boolean>' is not assignable to parameter of type '(a: ReaderTask<R1, number>) => ReaderTask<R2, boolean>'.
- dtslint/ReaderTask.ts#L50
[MISSING] error TS2345: Argument of type '(ma: ReaderTask<R2, number>) => ReaderTask<R2, number>' is not assignable to parameter of type '(a: ReaderTask<R1, number>) => ReaderTask<R2, number>'.
- dtslint/ReaderTask.ts#L76
[MISSING] error TS1259: Module '"/mnt/ts_downloads/_/m/fp-ts/node_modules/@types/glob/index"' can only be default-imported using the 'esModuleInterop' flag
- scripts/FileSystem.ts#L2
[MISSING] error TS2345: Argument of type 'undefined[]' is not assignable to parameter of type 'readonly never[]'.
- test/Foldable.ts#L54
- test/ReadonlyArray.ts#L1416

typescript-bot · 2025-01-03T22:59:34Z

Hey @RyanCavanaugh, the results of running the DT tests are ready.

There were interesting changes:

Branch only errors:

Package: lodash
Error:

Error: 
/mnt/vss/_work/1/DefinitelyTyped/types/lodash/lodash-tests.ts
  2900:5  error  TypeScript@local expected type to be:
  [AbcObject[], AbcObject[]]
got:
  [AbcObject[], never[]]              @definitelytyped/expect
  2950:5  error  TypeScript@local expected type to be:
  [AbcObject[], AbcObject[]]
got:
  [AbcObject[], never[]]              @definitelytyped/expect
  7297:5  error  TypeScript@local expected type to be:
  (...args: number[]) => boolean
got:
  (arg: number) => arg is number  @definitelytyped/expect
  7313:5  error  TypeScript@local expected type to be:
  (...args: number[]) => boolean
got:
  (arg: number) => arg is number  @definitelytyped/expect

✖ 4 problems (4 errors, 0 warnings)

    at combineErrorsAndWarnings (/mnt/vss/_work/1/DefinitelyTyped/node_modules/.pnpm/@definitelytyped+dtslint@0.2.28_typescript@5.8.0-dev.20250103/node_modules/@definitelytyped/dtslint/dist/index.js:194:28)
    at runTests (/mnt/vss/_work/1/DefinitelyTyped/node_modules/.pnpm/@definitelytyped+dtslint@0.2.28_typescript@5.8.0-dev.20250103/node_modules/@definitelytyped/dtslint/dist/index.js:186:20)

You can check the log here.

typescript-bot · 2025-01-03T23:08:40Z

@RyanCavanaugh
The results of the perf run you requested are in!

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - node (v18.15.0, x64)}
_Errors	₃₄	₃₄	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_62,363	_62,363	_~	_~	_~	_{p=1.000 n=6}
_Types	_50,395	_50,395	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{193,638k (± 0.77%)}	_{193,794k (± 0.73%)}	_~	_192,998k	_196,665k	_{p=0.575 n=6}
_{Parse Time}	_{1.31s (± 1.22%)}	_{1.31s (± 0.84%)}	_~	_1.29s	_1.32s	_{p=0.933 n=6}
_{Bind Time}	_0.72s	_0.72s	_~	_~	_~	_{p=1.000 n=6}
_{Check Time}	_{9.78s (± 0.52%)}	_{9.78s (± 0.26%)}	_~	_9.76s	_9.83s	_{p=1.000 n=6}
_{Emit Time}	_{2.73s (± 0.85%)}	_{2.72s (± 0.38%)}	_~	_2.71s	_2.74s	_{p=1.000 n=6}
_{Total Time}	_{14.53s (± 0.46%)}	_{14.53s (± 0.21%)}	_~	_14.51s	_14.59s	_{p=0.936 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₃₇	₀	_~	_~	_~	_{p=1.000 n=6+0}
_Symbols	_947,936	₀	_~	_~	_~	_{p=1.000 n=6+0}
_Types	_410,955	₀	_~	_~	_~	_{p=1.000 n=6+0}
_{Memory used}	_{1,225,791k (± 0.00%)}	_0k	_~	_~	_~	_{p=1.000 n=6+0}
_{Parse Time}	_{6.69s (± 0.72%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Bind Time}	_{1.88s (± 0.43%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Check Time}	_{32.00s (± 0.22%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Emit Time}	_{15.15s (± 0.25%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Total Time}	_{55.73s (± 0.17%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6+0}
_Symbols	_2,446,528	₀	_~	_~	_~	_{p=1.000 n=6+0}
_Types	_897,081	₀	_~	_~	_~	_{p=1.000 n=6+0}
_{Memory used}	_{2,311,140k (± 0.00%)}	_0k	_~	_~	_~	_{p=1.000 n=6+0}
_{Parse Time}	_{8.98s (± 0.54%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Bind Time}	_{2.12s (± 0.64%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Check Time}	_{73.01s (± 0.58%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Emit Time}	_{0.29s (± 1.92%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Total Time}	_{84.40s (± 0.51%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,226,880	_1,226,883	_{+3 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_266,745	_266,749	_{+4 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,479,167k (±12.00%)}	_{2,479,454k (±11.98%)}	_~	_2,357,505k	_3,086,305k	_{p=0.689 n=6}
_{Parse Time}	_{5.23s (± 1.15%)}	_{5.22s (± 1.83%)}	_~	_5.13s	_5.40s	_{p=0.575 n=6}
_{Bind Time}	_{1.77s (± 0.85%)}	_{1.75s (± 1.05%)}	_~	_1.72s	_1.77s	_{p=0.117 n=6}
_{Check Time}	_{35.24s (± 0.57%)}	_{35.30s (± 0.45%)}	_~	_35.15s	_35.57s	_{p=0.470 n=6}
_{Emit Time}	_{2.96s (± 2.27%)}	_{3.03s (± 4.51%)}	_~	_2.94s	_3.30s	_{p=0.810 n=6}
_{Total Time}	_{45.20s (± 0.41%)}	_{45.31s (± 0.68%)}	_~	_45.04s	_45.71s	_{p=0.630 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,226,880	_1,226,883	_{+3 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_266,745	_266,749	_{+4 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,938,889k (±11.44%)}	_{2,670,499k (±14.00%)}	_~	_2,428,572k	_3,154,186k	_{p=0.066 n=6}
_{Parse Time}	_{6.95s (± 1.31%)}	_{6.88s (± 1.93%)}	_~	_6.78s	_7.10s	_{p=0.261 n=6}
_{Bind Time}	_{2.17s (± 0.63%)}	_{2.20s (± 2.39%)}	_~	_2.10s	_2.25s	_{p=0.077 n=6}
_{Check Time}	_{42.74s (± 0.77%)}	_{42.73s (± 0.60%)}	_~	_42.40s	_43.07s	_{p=0.936 n=6}
_{Emit Time}	_{3.46s (± 0.92%)}	_{3.47s (± 1.64%)}	_~	_3.38s	_3.53s	_{p=0.688 n=6}
_{Total Time}	_{55.32s (± 0.76%)}	_{55.29s (± 0.68%)}	_~	_54.99s	_55.81s	_{p=1.000 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_262,439	_262,441	_{+2 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_106,628	_106,629	_{+1 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{440,214k (± 0.01%)}	_{440,305k (± 0.02%)}	_~	_440,200k	_440,383k	_{p=0.066 n=6}
_{Parse Time}	_{3.54s (± 1.17%)}	_{3.54s (± 1.02%)}	_~	_3.49s	_3.59s	_{p=0.747 n=6}
_{Bind Time}	_{1.31s (± 1.12%)}	_{1.32s (± 0.62%)}	_~	_1.31s	_1.33s	_{p=0.284 n=6}
_{Check Time}	_{18.95s (± 0.50%)}	_{18.97s (± 0.47%)}	_~	_18.84s	_19.10s	_{p=0.810 n=6}
_{Emit Time}	_{1.53s (± 1.35%)}	_{1.52s (± 1.30%)}	_~	_1.49s	_1.55s	_{p=0.291 n=6}
_{Total Time}	_{25.32s (± 0.49%)}	_{25.34s (± 0.34%)}	_~	_25.22s	_25.44s	_{p=0.688 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₇₀	₇₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_226,062	_226,062	_~	_~	_~	_{p=1.000 n=6}
_Types	_94,488	_94,488	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{371,662k (± 0.05%)}	_{371,639k (± 0.01%)}	_~	_371,599k	_371,720k	_{p=0.936 n=6}
_{Parse Time}	_{2.91s (± 0.85%)}	_{2.91s (± 0.64%)}	_~	_2.89s	_2.94s	_{p=0.807 n=6}
_{Bind Time}	_{1.60s (± 0.92%)}	_{1.59s (± 1.85%)}	_~	_1.56s	_1.64s	_{p=0.629 n=6}
_{Check Time}	_{16.48s (± 0.48%)}	_{16.52s (± 0.27%)}	_~	_16.46s	_16.57s	_{p=0.423 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{20.98s (± 0.40%)}	_{21.03s (± 0.29%)}	_~	_20.92s	_21.08s	_{p=0.377 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₃	₀	_~	_~	_~	_{p=1.000 n=6+0}
_Symbols	_3,230,418	₀	_~	_~	_~	_{p=1.000 n=6+0}
_Types	_1,112,109	₀	_~	_~	_~	_{p=1.000 n=6+0}
_{Memory used}	_{3,294,842k (± 0.01%)}	_0k	_~	_~	_~	_{p=1.000 n=6+0}
_{Parse Time}	_{14.16s (± 0.38%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Bind Time}	_{4.63s (± 3.02%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Check Time}	_{89.85s (± 2.94%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Emit Time}	_{28.03s (± 3.18%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{Total Time}	_{136.66s (± 1.58%)}	_0s	_~	_~	_~	_{p=1.000 n=6+0}
_{webpack - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_291,562	_291,561	_{-1 (- 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_118,971	_118,971	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{445,370k (± 0.02%)}	_{445,482k (± 0.04%)}	_~	_445,250k	_445,674k	_{p=0.230 n=6}
_{Parse Time}	_{4.09s (± 0.93%)}	_{4.11s (± 0.82%)}	_~	_4.05s	_4.15s	_{p=0.377 n=6}
_{Bind Time}	_{1.78s (± 1.30%)}	_{1.79s (± 0.92%)}	_~	_1.76s	_1.80s	_{p=0.871 n=6}
_{Check Time}	_{18.72s (± 0.41%)}	_{18.91s (± 0.74%)}	_{+0.19s (+ 1.01%)}	_18.77s	_19.14s	_{p=0.037 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{24.60s (± 0.34%)}	_{24.81s (± 0.56%)}	_{+0.21s (+ 0.84%)}	_24.62s	_24.97s	_{p=0.020 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_555,017	_555,033	_{+16 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_186,115	_186,116	_{+1 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{494,042k (± 0.01%)}	_{494,045k (± 0.01%)}	_~	_493,928k	_494,123k	_{p=0.936 n=6}
_{Parse Time}	_{4.24s (± 0.60%)}	_{4.23s (± 0.35%)}	_~	_4.21s	_4.25s	_{p=0.360 n=6}
_{Bind Time}	_{1.47s (± 0.82%)}	_{1.45s (± 1.28%)}	_~	_1.42s	_1.47s	_{p=0.438 n=6}
_{Check Time}	_{24.31s (± 0.35%)}	_{24.22s (± 0.40%)}	_~	_24.05s	_24.32s	_{p=0.196 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{30.01s (± 0.25%)}	_{29.91s (± 0.30%)}	_~	_29.75s	_30.01s	_{p=0.064 n=6}

System info unknown

Hosts

node (v18.15.0, x64)

Scenarios

Compiler-Unions - node (v18.15.0, x64)
angular-1 - node (v18.15.0, x64)
mui-docs - node (v18.15.0, x64)
self-build-src - node (v18.15.0, x64)
self-build-src-public-api - node (v18.15.0, x64)
self-compiler - node (v18.15.0, x64)
ts-pre-modules - node (v18.15.0, x64)
vscode - node (v18.15.0, x64)
webpack - node (v18.15.0, x64)
xstate-main - node (v18.15.0, x64)

_Benchmark	_Name	_Iterations
_Current	_pr	₆
_Baseline	_baseline	₆

Developer Information:

Download Benchmarks

typescript-bot · 2025-01-04T00:13:46Z

@RyanCavanaugh Here are the results of running the top 400 repos with tsc comparing main and refs/pull/60834/merge:

Something interesting changed - please have a look.

Details

darkreader/darkreader

2 of 5 projects failed to build with the old tsc and were ignored

src/tsconfig.json

error TS2339: Property 'id' does not exist on type 'never'.
- src/background/tab-manager.ts#L369
- src/background/tab-manager.ts#L375

mui/material-ui

23 of 85 projects failed to build with the old tsc and were ignored

packages/api-docs-builder-core/tsconfig.json

error TS2339: Property 'name' does not exist on type 'never'.
- packages/api-docs-builder/utils/extractInfoFromType.ts#L46
- packages/api-docs-builder/utils/extractInfoFromType.ts#L46

packages/api-docs-builder/tsconfig.json

error TS2339: Property 'name' does not exist on type 'never'.
- packages/api-docs-builder/utils/extractInfoFromType.ts#L46
- packages/api-docs-builder/utils/extractInfoFromType.ts#L46

Andarist · 2025-01-04T10:44:51Z

could I get a preview build for this one? it would make it easier to investigate some of the above changes, cc @jakebailey

I'm not sure what happens with Effect. It's rather unlikely this PR is at fault here - it reports that it can't find its typedefs at all
darkreader's repro can be seen here. It's related to the inferred false return type in that filter. It has no effect on tab's narrowing but given it always returns false it now has been inferred as a type predicate that rejects everything (at all times). It boils down to accessing an index signature type that isn't typed as optional (with | undefined in its type). Is it an acceptable break? The workaround is simple, the return type can be annotated as boolean (or the index signature can be "fixed"). It's not unlikely that some .filters in the wild might get affected by this - the same happened with the original Dan's PR.
material-ui's repro can be seen here. This is basically the same case as the darkreader's one.

jakebailey · 2025-01-04T17:09:10Z

@typescript-bot pack this

typescript-bot · 2025-01-04T17:09:15Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`pack this`	✅ Started	✅ Results

typescript-bot · 2025-01-04T17:11:08Z

Hey @jakebailey, I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
    "devDependencies": {
        "typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/164470/artifacts?artifactName=tgz&fileId=5E8897D74FF24E8FC340FBB531CB44D4A4CF8253508A926AA310D2E4FFF719B402&fileName=/typescript-5.8.0-insiders.20250104.tgz"
    }
}

and then running npm install.

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/pr-build@5.8.0-pr-60834-11".;

typescript-bot · 2026-03-24T21:20:56Z

With 6.0 out as the final release vehicle for this codebase, we're closing all PRs that don't fit the merge criteria for post-6.0 patches. If you think this was a mistake and this PR fits the post-6.0 patch criteria, please post to the 6.0 iteration issue with details (specifically, which PR and which patch criteria it satisfies).

Next steps for PRs:

For crash bugfixes or language service improvements, PRs are currently accepted at the typescript-go repo
Changes to type system behavior should wait until after 7.0, at which point mainline TypeScript development will resume in this repository with the Go codebase
Library file updates (lib.d.ts etc) continue to live in this repo or the DOM Generator repo as appropriate

typescript-bot added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Dec 20, 2024

Andarist force-pushed the infer-type-predicates-based-on-context branch from 709b33d to 655602d Compare December 20, 2024 23:22

Andarist closed this Dec 20, 2024

Andarist reopened this Dec 20, 2024

Andarist force-pushed the infer-type-predicates-based-on-context branch from 655602d to bb1dd39 Compare December 20, 2024 23:39

Infer non-narrowing predicates when the contextual signature is a typ…

332ecc3

…e predicate

Andarist force-pushed the infer-type-predicates-based-on-context branch from bb1dd39 to 332ecc3 Compare December 20, 2024 23:41

Andarist added 2 commits December 21, 2024 13:23

handle boolean literals

e10853f

update baselines

1a36871

typescript-bot closed this Mar 24, 2026

github-project-automation bot moved this from Not started to Done in PR Backlog Mar 24, 2026

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