Improve `unknown` narrowing by negated type predicates by Andarist · Pull Request #60795 · microsoft/TypeScript

Mateusz Burzyński (Andarist) · 2024-12-17T19:17:32Z

Gabriela Araujo Britto (gabritto) · 2024-12-17T20:05:04Z

TypeScript Bot (@typescript-bot) test it

TypeScript Bot (typescript-bot) · 2024-12-17T20:05:09Z

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 (typescript-bot) · 2024-12-17T20:26:38Z

Gabriela Araujo Britto (@gabritto) Here are the results of running the user tests with tsc comparing main and refs/pull/60795/merge:

Everything looks good!

TypeScript Bot (typescript-bot) · 2024-12-17T20:27:19Z

Hey Gabriela Araujo Britto (@gabritto), the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

TypeScript Bot (typescript-bot) · 2024-12-17T20:48:02Z

Gabriela Araujo Britto (@gabritto)
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}	_{193,677k (± 0.76%)}	_{193,082k (± 0.07%)}	_~	_193,008k	_193,350k	_{p=1.000 n=6}
_{Parse Time}	_{1.31s (± 0.57%)}	_{1.30s (± 0.97%)}	_~	_1.29s	_1.32s	_{p=0.115 n=6}
_{Bind Time}	_0.72s	_0.72s	_~	_~	_~	_{p=1.000 n=6}
_{Check Time}	_{9.76s (± 0.45%)}	_{9.78s (± 0.26%)}	_~	_9.76s	_9.83s	_{p=0.373 n=6}
_{Emit Time}	_{2.72s (± 1.49%)}	_{2.73s (± 0.51%)}	_~	_2.70s	_2.74s	_{p=0.565 n=6}
_{Total Time}	_{14.51s (± 0.43%)}	_{14.53s (± 0.16%)}	_~	_14.50s	_14.56s	_{p=0.936 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₃₇	₃₇	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_947,936	_947,936	_~	_~	_~	_{p=1.000 n=6}
_Types	_410,955	_410,955	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{1,225,832k (± 0.00%)}	_{1,225,817k (± 0.00%)}	_~	_1,225,759k	_1,225,866k	_{p=0.575 n=6}
_{Parse Time}	_{6.66s (± 0.69%)}	_{6.64s (± 0.51%)}	_~	_6.60s	_6.68s	_{p=0.468 n=6}
_{Bind Time}	_{1.88s (± 0.29%)}	_{1.89s (± 0.22%)}	_~	_1.88s	_1.89s	_{p=0.282 n=6}
_{Check Time}	_{31.90s (± 0.27%)}	_{31.97s (± 0.23%)}	_~	_31.85s	_32.04s	_{p=0.173 n=6}
_{Emit Time}	_{15.18s (± 0.62%)}	_{15.19s (± 0.35%)}	_~	_15.12s	_15.24s	_{p=0.747 n=6}
_{Total Time}	_{55.63s (± 0.17%)}	_{55.69s (± 0.20%)}	_~	_55.53s	_55.84s	_{p=0.336 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,448,617	_2,448,617	_~	_~	_~	_{p=1.000 n=6}
_Types	_896,282	_896,282	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,320,401k (± 0.00%)}	_{2,320,426k (± 0.00%)}	_~	_2,320,369k	_2,320,464k	_{p=0.173 n=6}
_{Parse Time}	_{9.40s (± 0.16%)}	_{9.41s (± 0.25%)}	_~	_9.37s	_9.43s	_{p=0.566 n=6}
_{Bind Time}	_{2.24s (± 0.36%)}	_{2.25s (± 0.24%)}	_~	_2.24s	_2.25s	_{p=0.441 n=6}
_{Check Time}	_{73.44s (± 0.63%)}	_{73.43s (± 0.42%)}	_~	_73.04s	_73.81s	_{p=0.810 n=6}
_{Emit Time}	_{0.28s (± 2.26%)}	_{0.29s (± 2.85%)}	_~	_0.28s	_0.30s	_{p=0.177 n=6}
_{Total Time}	_{85.37s (± 0.55%)}	_{85.37s (± 0.35%)}	_~	_84.99s	_85.74s	_{p=0.810 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,225,390	_1,225,392	_{+2 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_266,584	_266,584	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,475,670k (± 7.59%)}	_{2,354,436k (± 0.03%)}	_~	_2,353,546k	_2,355,328k	_{p=0.575 n=6}
_{Parse Time}	_{5.25s (± 1.45%)}	_{5.23s (± 0.42%)}	_~	_5.20s	_5.26s	_{p=0.518 n=6}
_{Bind Time}	_{1.78s (± 0.98%)}	_{1.78s (± 1.12%)}	_~	_1.76s	_1.81s	_{p=1.000 n=6}
_{Check Time}	_{35.10s (± 0.63%)}	_{35.26s (± 0.38%)}	_~	_35.08s	_35.44s	_{p=0.173 n=6}
_{Emit Time}	_{2.95s (± 2.48%)}	_{2.97s (± 1.51%)}	_~	_2.90s	_3.04s	_{p=0.421 n=6}
_{Total Time}	_{45.08s (± 0.47%)}	_{45.25s (± 0.37%)}	_~	_45.06s	_45.49s	_{p=0.128 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,225,390	_1,225,392	_{+2 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_266,584	_266,584	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{3,029,128k (± 9.76%)}	_{2,908,581k (±12.86%)}	_~	_2,424,626k	_3,150,792k	_{p=1.000 n=6}
_{Parse Time}	_{7.00s (± 1.38%)}	_{6.95s (± 1.77%)}	_~	_6.77s	_7.11s	_{p=0.575 n=6}
_{Bind Time}	_{2.14s (± 1.71%)}	_{2.15s (± 1.33%)}	_~	_2.10s	_2.19s	_{p=0.806 n=6}
_{Check Time}	_{42.90s (± 0.49%)}	_{42.83s (± 0.80%)}	_~	_42.36s	_43.28s	_{p=0.748 n=6}
_{Emit Time}	_{3.49s (± 1.80%)}	_{3.45s (± 2.27%)}	_~	_3.37s	_3.56s	_{p=0.298 n=6}
_{Total Time}	_{55.53s (± 0.51%)}	_{55.37s (± 0.84%)}	_~	_54.66s	_55.88s	_{p=0.575 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_262,278	_262,280	_{+2 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_106,628	_106,628	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{439,877k (± 0.01%)}	_{439,917k (± 0.01%)}	_~	_439,864k	_440,027k	_{p=0.298 n=6}
_{Parse Time}	_{3.53s (± 1.21%)}	_{3.53s (± 0.97%)}	_~	_3.47s	_3.57s	_{p=0.517 n=6}
_{Bind Time}	_{1.32s (± 0.39%)}	_{1.32s (± 0.96%)}	_~	_1.31s	_1.34s	_{p=0.931 n=6}
_{Check Time}	_{18.96s (± 0.44%)}	_{18.94s (± 0.37%)}	_~	_18.82s	_19.03s	_{p=0.809 n=6}
_{Emit Time}	_{1.53s (± 0.99%)}	_{1.53s (± 0.76%)}	_~	_1.52s	_1.55s	_{p=0.868 n=6}
_{Total Time}	_{25.33s (± 0.32%)}	_{25.32s (± 0.39%)}	_~	_25.20s	_25.45s	_{p=0.936 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}	_{371,644k (± 0.03%)}	_{371,606k (± 0.01%)}	_~	_371,562k	_371,652k	_{p=0.936 n=6}
_{Parse Time}	_{2.89s (± 0.58%)}	_{2.89s (± 0.60%)}	_~	_2.87s	_2.92s	_{p=0.867 n=6}
_{Bind Time}	_{1.58s (± 0.48%)}	_{1.58s (± 1.86%)}	_~	_1.54s	_1.63s	_{p=0.620 n=6}
_{Check Time}	_{16.49s (± 0.22%)}	_{16.51s (± 0.63%)}	_~	_16.38s	_16.65s	_{p=1.000 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{20.96s (± 0.20%)}	_{20.99s (± 0.43%)}	_~	_20.84s	_21.09s	_{p=0.518 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_3,220,108	_3,220,108	_~	_~	_~	_{p=1.000 n=6}
_Types	_1,107,848	_1,107,853	_{+5 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,286,380k (± 0.01%)}	_{3,286,563k (± 0.01%)}	_~	_3,286,129k	_3,286,945k	_{p=0.298 n=6}
_{Parse Time}	_{14.19s (± 0.36%)}	_{14.19s (± 0.80%)}	_~	_14.06s	_14.37s	_{p=0.873 n=6}
_{Bind Time}	_{4.55s (± 1.41%)}	_{4.54s (± 0.85%)}	_~	_4.48s	_4.60s	_{p=0.683 n=6}
_{Check Time}	_{87.63s (± 1.35%)}	_{86.93s (± 0.28%)}	_~	_86.71s	_87.28s	_{p=0.128 n=6}
_{Emit Time}	_{28.40s (± 1.86%)}	_{28.28s (± 2.65%)}	_~	_27.40s	_29.29s	_{p=0.689 n=6}
_{Total Time}	_{134.78s (± 0.97%)}	_{133.94s (± 0.65%)}	_~	_132.81s	_135.11s	_{p=0.298 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_291,463	_291,463	_~	_~	_~	_{p=1.000 n=6}
_Types	_118,920	_118,920	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{445,205k (± 0.03%)}	_{445,107k (± 0.02%)}	_~	_445,009k	_445,211k	_{p=0.230 n=6}
_{Parse Time}	_{4.09s (± 1.02%)}	_{4.09s (± 1.15%)}	_~	_4.04s	_4.16s	_{p=1.000 n=6}
_{Bind Time}	_{1.78s (± 1.20%)}	_{1.78s (± 0.68%)}	_~	_1.76s	_1.79s	_{p=0.622 n=6}
_{Check Time}	_{18.77s (± 0.38%)}	_{18.72s (± 0.65%)}	_~	_18.50s	_18.83s	_{p=0.748 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{24.64s (± 0.35%)}	_{24.59s (± 0.58%)}	_~	_24.33s	_24.72s	_{p=0.688 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_552,233	_552,233	_~	_~	_~	_{p=1.000 n=6}
_Types	_184,971	_184,971	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{492,401k (± 0.00%)}	_{492,387k (± 0.01%)}	_~	_492,343k	_492,473k	_{p=0.378 n=6}
_{Parse Time}	_{3.43s (± 0.93%)}	_{3.42s (± 0.73%)}	_~	_3.40s	_3.46s	_{p=0.570 n=6}
_{Bind Time}	_{1.18s (± 0.99%)}	_{1.17s (± 0.88%)}	_~	_1.15s	_1.18s	_{p=0.117 n=6}
_{Check Time}	_{19.45s (± 0.36%)}	_{19.42s (± 0.42%)}	_~	_19.32s	_19.52s	_{p=0.574 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{24.06s (± 0.21%)}	_{24.01s (± 0.30%)}	_~	_23.93s	_24.13s	_{p=0.261 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 (typescript-bot) · 2024-12-17T21:37:02Z

Gabriela Araujo Britto (@gabritto) Here are the results of running the top 400 repos with tsc comparing main and refs/pull/60795/merge:

Everything looks good!

Gabriela Araujo Britto (gabritto) · 2024-12-18T18:18:14Z

TypeScript Bot (@typescript-bot) pack this

TypeScript Bot (typescript-bot) · 2024-12-18T18:18:18Z

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

Command	Status	Results
`pack this`	✅ Started	✅ Results

TypeScript Bot (typescript-bot) · 2024-12-18T18:20:07Z

Hey Gabriela Araujo Britto (@gabritto), 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/164425/artifacts?artifactName=tgz&fileId=854838C8C1BC0A3E52BA95C06664905DE93FF91DAF52B7D70630FEA7698FFC8002&fileName=/typescript-5.8.0-insiders.20241218.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-60795-8".;

Gabriela Araujo Britto (gabritto) · 2024-12-18T18:44:08Z

I'm now slightly curious about what it would take to fix this example: https://www.typescriptlang.org/play/?ts=5.8.0-dev.20241218#code/GYVwdgxgLglg9mABAIwIYBMA8AVRBTADyjzHQGdFwBrMOAdzAD4AKAgLkWwEoOA3OGOkQBvAFCJEMYIlaIAhAF5KpPMBhg86LiPETEEBGSiIAnh2EBfREoIBuXRd14ANmTw69+w8bOIwIZ2dEAB9ldFV1TWtEO0QAejjEAFEAJxS4FI4AAwIsyQpaYzBUNPoogAs8FLwHUUdRUEhYBEQAczg4LFxCYlIKSxC-AKDQ8HC1DXQWdk4eRH5BD0lpWUUwiMntMU8DMCNTcysbewlHCRc3JYld-d9-QMGxjajj+MSAdQyqMmzc-L8Suk6BUqjVTnUgA
I used it as an example of why you should use union types explicitly in #56941, but at some point I might have to update that example to not use unknown, as that is a special type we sometimes know to break into a union.

Improve unknown narrowing by negated type predicates

6fdf096

TypeScript Bot (typescript-bot) added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Dec 17, 2024

Gabriela Araujo Britto (gabritto) reviewed Dec 17, 2024

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Comment thread src/compiler/checker.ts Outdated

use recombineUnknownType

042aced

Mateusz Burzyński (Andarist) requested a review from Gabriela Araujo Britto (gabritto) December 18, 2024 06:26

Gabriela Araujo Britto (gabritto) approved these changes Dec 18, 2024

View reviewed changes

Gabriela Araujo Britto (gabritto) merged commit 0dda037 into microsoft:main Dec 18, 2024

Mateusz Burzyński (Andarist) mentioned this pull request Dec 19, 2024

Improve narrowing of generic types constrained to unknown #60816

Closed

Mateusz Burzyński (Andarist) deleted the improve-negated-unknown-narrowing-by-type-predicate branch December 19, 2024 11:23

Nathan Shively-Sanders (sandersn) removed this from PR Backlog Apr 22, 2025

Mateusz Burzyński (Andarist) mentioned this pull request Jun 4, 2025

Port "Improve unknown narrowing by negated type predicates" microsoft/typescript-go#1044

Merged

Microsoft (microsoft) locked as resolved and limited conversation to collaborators Oct 15, 2025

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Improve `unknown` narrowing by negated type predicates - #60795

Improve `unknown` narrowing by negated type predicates#60795
Gabriela Araujo Britto (gabritto) merged 2 commits into
microsoft:mainfrom
Andarist:improve-negated-unknown-narrowing-by-type-predicate

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