Infer type parameters from indexes on those parameters by Andarist · Pull Request #53017 · microsoft/TypeScript

Andarist · 2023-02-28T09:50:10Z

…an alias in lib

…straint

…properties

typescript-bot · 2023-02-28T09:50:17Z

The TypeScript team hasn't accepted the linked issue #51612. If you can get it accepted, this PR will have a better chance of being reviewed.

src/compiler/checker.ts

weswigham

I had #20126 which was pretty functional a long time ago, which we basically only didn't take because nobody could be bothered to care about it without a backing issue (myself included), but that seems to be an even more general version of this (or at least relied on a similar partial inferencing mechanism), since these kinds of partial inferences that you combine later are applicable beyond reverse mapped types.

src/compiler/checker.ts

…ties-of-reverse-mapped-types

…to infer-concrete-properties-of-reverse-mapped-types-with-wes

…le reverse mapped type

src/compiler/checker.ts

…traint

jakebailey · 2025-12-01T19:36:15Z

@typescript-bot test it
@typescript-bot pack this

typescript-bot · 2025-12-01T19:36:19Z

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

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

typescript-bot · 2025-12-01T19:40:19Z

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/166633/artifacts?artifactName=tgz&fileId=E5F9CEBCCB3B4DBB52F1F9642B36C892BB89227CBD41EAD91C6DBFD5FA8129EC02&fileName=/typescript-6.0.0-insiders.20251201.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/[email protected]".;

typescript-bot · 2025-12-01T20:00:23Z

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

There were interesting changes:

Branch only errors:

Package: rdfjs__data-model
Error:

Error: 
/mnt/vss/_work/1/DefinitelyTyped/types/rdfjs__data-model/rdfjs__data-model-tests.ts
  76:5  error  TypeScript@local compile error: 
Unused '@ts-expect-error' directive  @definitelytyped/expect

✖ 1 problem (1 error, 0 warnings)

    at combineErrorsAndWarnings (/mnt/vss/_work/1/DefinitelyTyped/node_modules/.pnpm/@[email protected][email protected]/node_modules/@definitelytyped/dtslint/dist/index.js:199:28)
    at runTests (/mnt/vss/_work/1/DefinitelyTyped/node_modules/.pnpm/@[email protected][email protected]/node_modules/@definitelytyped/dtslint/dist/index.js:191:20)

You can check the log here.

typescript-bot · 2025-12-01T20:04:55Z

@jakebailey Here are the results of running the user tests with tsc comparing main and refs/pull/53017/merge:

There were infrastructure failures potentially unrelated to your change:

1 instance of "Git clone failed"

Otherwise...

Something interesting changed - please have a look.

Details

webpack

tsconfig.types.test.json

[NEW] error TS2345: Argument of type 'Comparator<Record<string | number | symbol, number>>' is not assignable to parameter of type '(a: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }, b: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }) => number'.
- lib/optimize/ConcatenatedModule.js#L1036

tsconfig.types.json

[NEW] error TS2345: Argument of type 'Comparator<Record<string | number | symbol, number>>' is not assignable to parameter of type '(a: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }, b: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }) => number'.
- lib/optimize/ConcatenatedModule.js#L1036

tsconfig.json

[NEW] error TS2345: Argument of type 'Comparator<Record<string | number | symbol, number>>' is not assignable to parameter of type '(a: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }, b: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }) => number'.
- lib/optimize/ConcatenatedModule.js#L1036

typescript-bot · 2025-12-01T20:29:56Z

@jakebailey
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	₁	₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_62,370	_62,407	_{+37 (+ 0.06%)}	_~	_~	_{p=0.001 n=6}
_Types	_50,386	_50,458	_{+72 (+ 0.14%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{193,848k (± 0.96%)}	_{195,223k (± 0.90%)}	_{+1,375k (+ 0.71%)}	_192,768k	_196,435k	_{p=0.031 n=6}
_{Parse Time}	_{1.30s (± 0.79%)}	_{1.29s (± 0.76%)}	_~	_1.28s	_1.31s	_{p=0.091 n=6}
_{Bind Time}	_{0.75s (± 0.54%)}	_0.75s	_~	_~	_~	_{p=0.405 n=6}
_{Check Time}	_{9.90s (± 0.24%)}	_{9.97s (± 0.33%)}	_{+0.06s (+ 0.64%)}	_9.90s	_9.99s	_{p=0.028 n=6}
_{Emit Time}	_{2.74s (± 0.80%)}	_{2.75s (± 0.36%)}	_~	_2.74s	_2.76s	_{p=0.324 n=6}
_{Total Time}	_{14.69s (± 0.24%)}	_{14.76s (± 0.24%)}	_{+0.07s (+ 0.44%)}	_14.69s	_14.78s	_{p=0.015 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_956,047	_949,829	_{-6,218 (- 0.65%)}	_~	_~	_{p=0.001 n=6}
_Types	_415,881	_411,890	_{-3,991 (- 0.96%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{1,255,005k (± 0.01%)}	_{1,246,583k (± 0.00%)}	_{-8,423k (- 0.67%)}	_1,246,533k	_1,246,651k	_{p=0.005 n=6}
_{Parse Time}	_{6.54s (± 0.71%)}	_{6.54s (± 0.68%)}	_~	_6.49s	_6.61s	_{p=0.872 n=6}
_{Bind Time}	_{1.96s (± 0.42%)}	_{1.96s (± 0.32%)}	_~	_1.95s	_1.97s	_{p=0.432 n=6}
_{Check Time}	_{32.31s (± 0.23%)}	_{32.36s (± 0.36%)}	_~	_32.19s	_32.48s	_{p=0.377 n=6}
_{Emit Time}	_{14.90s (± 0.15%)}	_{14.90s (± 0.27%)}	_~	_14.83s	_14.95s	_{p=0.746 n=6}
_{Total Time}	_{55.70s (± 0.17%)}	_{55.76s (± 0.13%)}	_~	_55.62s	_55.84s	_{p=0.470 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,722,088	_2,720,094	_{-1,994 (- 0.07%)}	_~	_~	_{p=0.001 n=6}
_Types	_937,484	_936,130	_{-1,354 (- 0.14%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,050,965k (± 0.00%)}	_{3,047,175k (± 0.00%)}	_{-3,790k (- 0.12%)}	_3,047,019k	_3,047,309k	_{p=0.005 n=6}
_{Parse Time}	_{8.55s (± 0.19%)}	_{8.53s (± 0.20%)}	_~	_8.51s	_8.55s	_{p=0.121 n=6}
_{Bind Time}	_{2.32s (± 0.79%)}	_{2.32s (± 0.65%)}	_~	_2.29s	_2.33s	_{p=1.000 n=6}
_{Check Time}	_{93.09s (± 0.30%)}	_{92.55s (± 0.36%)}	_{-0.55s (- 0.59%)}	_92.19s	_93.02s	_{p=0.031 n=6}
_{Emit Time}	_{0.31s (± 1.68%)}	_{0.31s (± 2.04%)}	_~	_0.30s	_0.32s	_{p=0.386 n=6}
_{Total Time}	_{104.27s (± 0.26%)}	_{103.71s (± 0.33%)}	_{-0.56s (- 0.54%)}	_103.35s	_104.16s	_{p=0.030 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,251,545	_1,251,990	_{+445 (+ 0.04%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,756	_260,698	_{+942 (+ 0.36%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,514,131k (±11.84%)}	_{2,455,118k (± 6.07%)}	_~	_2,393,577k	_2,759,564k	_{p=0.066 n=6}
_{Parse Time}	_{5.20s (± 1.01%)}	_{5.15s (± 1.05%)}	_~	_5.05s	_5.20s	_{p=0.471 n=6}
_{Bind Time}	_{1.82s (± 1.70%)}	_{1.82s (± 1.08%)}	_~	_1.80s	_1.85s	_{p=1.000 n=6}
_{Check Time}	_{35.45s (± 0.49%)}	_{35.34s (± 0.61%)}	_~	_34.97s	_35.62s	_{p=0.423 n=6}
_{Emit Time}	_{2.97s (± 1.80%)}	_{2.98s (± 1.85%)}	_~	_2.89s	_3.04s	_{p=0.748 n=6}
_{Total Time}	_{45.46s (± 0.39%)}	_{45.30s (± 0.50%)}	_~	_44.90s	_45.57s	_{p=0.297 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,251,545	_1,251,990	_{+445 (+ 0.04%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,756	_260,698	_{+942 (+ 0.36%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,067,155k (± 9.63%)}	_{3,068,699k (± 9.65%)}	_{+1,544k (+ 0.05%)}	_2,463,786k	_3,190,055k	_{p=0.045 n=6}
_{Parse Time}	_{6.77s (± 1.87%)}	_{6.78s (± 0.45%)}	_~	_6.72s	_6.81s	_{p=0.873 n=6}
_{Bind Time}	_{2.25s (± 0.54%)}	_{2.25s (± 0.67%)}	_~	_2.23s	_2.27s	_{p=0.687 n=6}
_{Check Time}	_{43.13s (± 0.40%)}	_{43.23s (± 0.16%)}	_~	_43.15s	_43.34s	_{p=0.378 n=6}
_{Emit Time}	_{3.52s (± 1.55%)}	_{3.53s (± 1.78%)}	_~	_3.46s	_3.61s	_{p=0.630 n=6}
_{Total Time}	_{55.68s (± 0.60%)}	_{55.78s (± 0.15%)}	_~	_55.64s	_55.87s	_{p=0.575 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_264,177	_264,370	_{+193 (+ 0.07%)}	_~	_~	_{p=0.001 n=6}
_Types	_103,979	_104,380	_{+401 (+ 0.39%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{443,207k (± 0.03%)}	_{443,453k (± 0.01%)}	_{+247k (+ 0.06%)}	_443,409k	_443,506k	_{p=0.005 n=6}
_{Parse Time}	_{3.52s (± 0.31%)}	_{3.49s (± 0.93%)}	_~	_3.46s	_3.54s	_{p=0.250 n=6}
_{Bind Time}	_{1.36s (± 1.20%)}	_{1.37s (± 0.75%)}	_~	_1.36s	_1.39s	_{p=0.241 n=6}
_{Check Time}	_{19.18s (± 0.36%)}	_{19.16s (± 0.53%)}	_~	_19.08s	_19.30s	_{p=0.810 n=6}
_{Emit Time}	_{1.54s (± 0.53%)}	_{1.54s (± 1.28%)}	_~	_1.52s	_1.57s	_{p=0.323 n=6}
_{Total Time}	_{25.61s (± 0.25%)}	_{25.57s (± 0.29%)}	_~	_25.50s	_25.67s	_{p=0.296 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₇₂	₇₂	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_225,386	_225,487	_{+101 (+ 0.04%)}	_~	_~	_{p=0.001 n=6}
_Types	_94,304	_94,669	_{+365 (+ 0.39%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{370,104k (± 0.05%)}	_{370,356k (± 0.02%)}	_~	_370,241k	_370,476k	_{p=0.066 n=6}
_{Parse Time}	_{2.83s (± 0.69%)}	_{2.83s (± 0.66%)}	_~	_2.79s	_2.84s	_{p=0.869 n=6}
_{Bind Time}	_{1.63s (± 1.31%)}	_{1.64s (± 0.92%)}	_~	_1.62s	_1.66s	_{p=0.401 n=6}
_{Check Time}	_{16.52s (± 0.21%)}	_{16.64s (± 0.41%)}	_{+0.11s (+ 0.69%)}	_16.53s	_16.73s	_{p=0.013 n=6}
_{Emit Time}	_0.00s	_{0.00s (±154.76%)}	_~	_0.00s	_0.01s	_{p=0.174 n=6}
_{Total Time}	_{20.98s (± 0.11%)}	_{21.11s (± 0.35%)}	_{+0.13s (+ 0.60%)}	_20.98s	_21.20s	_{p=0.019 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₁₁	₁₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_4,070,590	_4,070,058	_{-532 (- 0.01%)}	_~	_~	_{p=0.001 n=6}
_Types	_1,282,214	_1,281,724	_{-490 (- 0.04%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,856,455k (± 0.00%)}	_{3,855,629k (± 0.00%)}	_{-827k (- 0.02%)}	_3,855,480k	_3,855,781k	_{p=0.005 n=6}
_{Parse Time}	_{15.68s (± 0.44%)}	_{15.67s (± 0.31%)}	_~	_15.62s	_15.73s	_{p=0.871 n=6}
_{Bind Time}	_{5.28s (± 0.58%)}	_{5.27s (± 0.58%)}	_~	_5.23s	_5.31s	_{p=0.745 n=6}
_{Check Time}	_{113.65s (± 3.60%)}	_{111.55s (± 0.92%)}	_~	_110.13s	_113.31s	_{p=0.575 n=6}
_{Emit Time}	_{44.05s (±12.03%)}	_{39.02s (± 0.65%)}	_~	_38.73s	_39.46s	_{p=0.066 n=6}
_{Total Time}	_{178.65s (± 3.34%)}	_{171.51s (± 0.57%)}	_{🟩-7.14s (- 4.00%)}	_170.28s	_173.17s	_{p=0.031 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₄₀	₄₁	_{+1 (+ 2.50%)}	_~	_~	_{p=0.001 n=6}
_Symbols	_380,434	_379,240	_{-1,194 (- 0.31%)}	_~	_~	_{p=0.001 n=6}
_Types	_166,705	_165,734	_{-971 (- 0.58%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{540,329k (± 0.02%)}	_{539,502k (± 0.03%)}	_{-827k (- 0.15%)}	_539,220k	_539,741k	_{p=0.005 n=6}
_{Parse Time}	_{4.69s (± 0.35%)}	_{4.68s (± 0.40%)}	_~	_4.65s	_4.70s	_{p=0.466 n=6}
_{Bind Time}	_{2.03s (± 0.72%)}	_{2.02s (± 0.60%)}	_~	_2.01s	_2.04s	_{p=0.408 n=6}
_{Check Time}	_{22.92s (± 0.26%)}	_{22.91s (± 0.25%)}	_~	_22.81s	_22.97s	_{p=0.936 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{29.64s (± 0.21%)}	_{29.62s (± 0.24%)}	_~	_29.51s	_29.71s	_{p=0.470 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₃₀	₃₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_690,397	_690,376	_{-21 (- 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_208,790	_209,009	_{+219 (+ 0.10%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{586,137k (± 0.03%)}	_{586,118k (± 0.03%)}	_~	_585,944k	_586,308k	_{p=0.810 n=6}
_{Parse Time}	_{4.18s (± 0.84%)}	_{4.18s (± 0.51%)}	_~	_4.14s	_4.20s	_{p=0.809 n=6}
_{Bind Time}	_{1.42s (± 0.53%)}	_{1.42s (± 1.50%)}	_~	_1.40s	_1.45s	_{p=1.000 n=6}
_{Check Time}	_{20.75s (± 1.56%)}	_{20.59s (± 1.68%)}	_~	_20.33s	_21.26s	_{p=0.520 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{26.35s (± 1.14%)}	_{26.19s (± 1.41%)}	_~	_25.91s	_26.91s	_{p=0.298 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 · 2025-12-01T20:58:53Z

@jakebailey Here are the results of running the top 400 repos with tsc comparing main and refs/pull/53017/merge:

Something interesting changed - please have a look.

Details

tldraw/tldraw

30 of 34 projects failed to build with the old tsc and were ignored

templates/branching-chat/tsconfig.json

error TS2345: Argument of type '{ x: number; y: number; id: TLShapeId; typeName: "shape"; type: "node"; rotation: number; index: IndexKey; parentId: TLParentId; isLocked: boolean; opacity: TLOpacityType; props: { ...; }; meta: JsonObject; }' is not assignable to parameter of type 'null | undefined'.
- templates/branching-chat/client/components/WorkflowToolbar.tsx#L54

…ties-of-reverse-mapped-types

jakebailey · 2025-12-02T17:37:28Z

@typescript-bot test it
@typescript-bot pack this

typescript-bot · 2025-12-02T17:37:33Z

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

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

typescript-bot · 2025-12-02T17:41:42Z

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/166648/artifacts?artifactName=tgz&fileId=A5C9819FA08C4C8EB063C5869BCF715A23EC7D7449F748DA8260A7323DB8A06D02&fileName=/typescript-6.0.0-insiders.20251202.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/[email protected]".;

typescript-bot · 2025-12-02T18:01:03Z

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

Everything looks the same!

You can check the log here.

typescript-bot · 2025-12-02T18:07:01Z

@jakebailey Here are the results of running the user tests with tsc comparing main and refs/pull/53017/merge:

There were infrastructure failures potentially unrelated to your change:

1 instance of "Git clone failed"

Otherwise...

Something interesting changed - please have a look.

Details

webpack

tsconfig.types.test.json

[NEW] error TS2345: Argument of type 'Comparator<Record<string | number | symbol, number>>' is not assignable to parameter of type '(a: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }, b: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }) => number'.
- lib/optimize/ConcatenatedModule.js#L1036

tsconfig.types.json

[NEW] error TS2345: Argument of type 'Comparator<Record<string | number | symbol, number>>' is not assignable to parameter of type '(a: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }, b: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }) => number'.
- lib/optimize/ConcatenatedModule.js#L1036

tsconfig.json

[NEW] error TS2345: Argument of type 'Comparator<Record<string | number | symbol, number>>' is not assignable to parameter of type '(a: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }, b: { connection: ModuleGraphConnection; sourceOrder: number; rangeStart: number | undefined; defer?: boolean | undefined; }) => number'.
- lib/optimize/ConcatenatedModule.js#L1036

typescript-bot · 2025-12-02T18:30:23Z

@jakebailey
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	₁	₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_62,370	_62,403	_{+33 (+ 0.05%)}	_~	_~	_{p=0.001 n=6}
_Types	_50,386	_50,442	_{+56 (+ 0.11%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{194,531k (± 0.99%)}	_{194,025k (± 0.93%)}	_~	_192,782k	_196,389k	_{p=0.810 n=6}
_{Parse Time}	_{1.30s (± 0.75%)}	_{1.30s (± 0.76%)}	_~	_1.29s	_1.31s	_{p=0.604 n=6}
_{Bind Time}	_0.75s	_0.75s	_~	_~	_~	_{p=1.000 n=6}
_{Check Time}	_{9.90s (± 0.44%)}	_{9.94s (± 0.19%)}	_~	_9.92s	_9.97s	_{p=0.066 n=6}
_{Emit Time}	_{2.74s (± 0.67%)}	_{2.76s (± 0.59%)}	_~	_2.74s	_2.78s	_{p=0.254 n=6}
_{Total Time}	_{14.69s (± 0.24%)}	_{14.75s (± 0.19%)}	_{+0.05s (+ 0.37%)}	_14.70s	_14.78s	_{p=0.028 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_956,047	_949,827	_{-6,220 (- 0.65%)}	_~	_~	_{p=0.001 n=6}
_Types	_415,881	_411,866	_{-4,015 (- 0.97%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{1,255,082k (± 0.00%)}	_{1,246,560k (± 0.00%)}	_{-8,521k (- 0.68%)}	_1,246,491k	_1,246,618k	_{p=0.005 n=6}
_{Parse Time}	_{6.52s (± 0.68%)}	_{6.55s (± 0.78%)}	_~	_6.49s	_6.62s	_{p=0.468 n=6}
_{Bind Time}	_{1.97s (± 0.41%)}	_{1.96s (± 0.21%)}	_~	_1.96s	_1.97s	_{p=0.248 n=6}
_{Check Time}	_{32.46s (± 0.40%)}	_{32.41s (± 0.26%)}	_~	_32.30s	_32.53s	_{p=0.689 n=6}
_{Emit Time}	_{14.91s (± 0.29%)}	_{14.88s (± 0.31%)}	_~	_14.81s	_14.95s	_{p=0.195 n=6}
_{Total Time}	_{55.85s (± 0.33%)}	_{55.79s (± 0.10%)}	_~	_55.73s	_55.87s	_{p=0.630 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,722,079	_2,720,085	_{-1,994 (- 0.07%)}	_~	_~	_{p=0.001 n=6}
_Types	_937,469	_936,103	_{-1,366 (- 0.15%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,050,889k (± 0.00%)}	_{3,047,126k (± 0.00%)}	_{-3,763k (- 0.12%)}	_3,047,047k	_3,047,190k	_{p=0.005 n=6}
_{Parse Time}	_{8.55s (± 0.18%)}	_{8.53s (± 0.21%)}	_{-0.03s (- 0.33%)}	_8.50s	_8.55s	_{p=0.023 n=6}
_{Bind Time}	_{2.31s (± 0.65%)}	_{2.33s (± 0.45%)}	_~	_2.31s	_2.34s	_{p=0.215 n=6}
_{Check Time}	_{92.71s (± 0.58%)}	_{92.79s (± 0.34%)}	_~	_92.45s	_93.21s	_{p=0.748 n=6}
_{Emit Time}	_{0.31s (± 2.44%)}	_{0.31s (± 2.41%)}	_~	_0.30s	_0.32s	_{p=0.487 n=6}
_{Total Time}	_{103.88s (± 0.52%)}	_{103.95s (± 0.31%)}	_~	_103.57s	_104.35s	_{p=0.936 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,251,545	_1,251,833	_{+288 (+ 0.02%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,756	_260,040	_{+284 (+ 0.11%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,760,412k (±14.45%)}	_{3,003,980k (± 9.89%)}	_~	_2,396,775k	_3,126,796k	_{p=0.173 n=6}
_{Parse Time}	_{6.58s (± 1.38%)}	_{6.66s (± 1.33%)}	_~	_6.49s	_6.73s	_{p=0.128 n=6}
_{Bind Time}	_{2.27s (± 2.44%)}	_{2.22s (± 1.27%)}	_~	_2.19s	_2.27s	_{p=0.229 n=6}
_{Check Time}	_{43.17s (± 0.71%)}	_{43.06s (± 0.39%)}	_~	_42.84s	_43.27s	_{p=0.810 n=6}
_{Emit Time}	_{3.61s (± 5.04%)}	_{3.54s (± 2.20%)}	_~	_3.43s	_3.64s	_{p=0.687 n=6}
_{Total Time}	_{55.61s (± 0.58%)}	_{55.47s (± 0.32%)}	_~	_55.21s	_55.67s	_{p=0.689 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,251,545	_1,251,833	_{+288 (+ 0.02%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,756	_260,040	_{+284 (+ 0.11%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,459,510k (± 0.03%)}	_{2,460,361k (± 0.02%)}	_~	_2,459,655k	_2,460,665k	_{p=0.066 n=6}
_{Parse Time}	_{5.34s (± 0.65%)}	_{5.32s (± 0.33%)}	_~	_5.29s	_5.34s	_{p=0.173 n=6}
_{Bind Time}	_{1.87s (± 1.04%)}	_{1.87s (± 0.44%)}	_~	_1.87s	_1.89s	_{p=0.242 n=6}
_{Check Time}	_{35.55s (± 0.39%)}	_{35.65s (± 0.35%)}	_~	_35.51s	_35.80s	_{p=0.298 n=6}
_{Emit Time}	_{3.03s (± 1.68%)}	_{3.05s (± 1.25%)}	_~	_2.99s	_3.09s	_{p=0.470 n=6}
_{Total Time}	_{45.82s (± 0.43%)}	_{45.90s (± 0.31%)}	_~	_45.72s	_46.09s	_{p=0.471 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_264,177	_264,286	_{+109 (+ 0.04%)}	_~	_~	_{p=0.001 n=6}
_Types	_103,979	_104,036	_{+57 (+ 0.05%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{443,187k (± 0.01%)}	_{443,359k (± 0.01%)}	_{+173k (+ 0.04%)}	_443,314k	_443,434k	_{p=0.005 n=6}
_{Parse Time}	_{3.50s (± 0.52%)}	_{3.50s (± 0.78%)}	_~	_3.46s	_3.54s	_{p=0.871 n=6}
_{Bind Time}	_{1.37s (± 1.07%)}	_{1.36s (± 1.20%)}	_~	_1.35s	_1.39s	_{p=0.512 n=6}
_{Check Time}	_{19.20s (± 0.32%)}	_{19.14s (± 0.41%)}	_~	_19.02s	_19.24s	_{p=0.297 n=6}
_{Emit Time}	_{1.53s (± 1.45%)}	_{1.54s (± 0.27%)}	_~	_1.53s	_1.54s	_{p=0.227 n=6}
_{Total Time}	_{25.60s (± 0.31%)}	_{25.54s (± 0.34%)}	_~	_25.42s	_25.66s	_{p=0.230 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₇₂	₇₂	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_225,386	_225,406	_{+20 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_Types	_94,304	_94,345	_{+41 (+ 0.04%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{370,150k (± 0.05%)}	_{370,328k (± 0.06%)}	_~	_370,107k	_370,652k	_{p=0.173 n=6}
_{Parse Time}	_{2.85s (± 0.97%)}	_{2.86s (± 0.88%)}	_~	_2.81s	_2.88s	_{p=0.746 n=6}
_{Bind Time}	_{1.65s (± 1.00%)}	_{1.64s (± 1.05%)}	_~	_1.61s	_1.66s	_{p=0.934 n=6}
_{Check Time}	_{16.61s (± 0.22%)}	_{16.74s (± 0.29%)}	_{+0.13s (+ 0.78%)}	_16.68s	_16.80s	_{p=0.005 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{21.10s (± 0.18%)}	_{21.24s (± 0.26%)}	_{+0.14s (+ 0.66%)}	_21.14s	_21.30s	_{p=0.008 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₁₁	₁₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_4,072,506	_4,071,974	_{-532 (- 0.01%)}	_~	_~	_{p=0.001 n=6}
_Types	_1,282,587	_1,282,093	_{-494 (- 0.04%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,857,921k (± 0.00%)}	_{3,857,026k (± 0.00%)}	_{-895k (- 0.02%)}	_3,856,814k	_3,857,269k	_{p=0.005 n=6}
_{Parse Time}	_{15.72s (± 0.72%)}	_{15.67s (± 0.45%)}	_~	_15.56s	_15.75s	_{p=0.375 n=6}
_{Bind Time}	_{5.30s (± 1.34%)}	_{5.38s (± 2.43%)}	_~	_5.28s	_5.55s	_{p=0.147 n=6}
_{Check Time}	_{111.56s (± 2.60%)}	_{113.89s (± 3.41%)}	_~	_110.78s	_121.61s	_{p=0.128 n=6}
_{Emit Time}	_{38.94s (± 0.37%)}	_{43.08s (±14.98%)}	_~	_38.68s	_54.87s	_{p=0.689 n=6}
_{Total Time}	_{171.51s (± 1.74%)}	_{178.02s (± 5.63%)}	_~	_170.62s	_197.33s	_{p=0.066 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₄₀	₄₁	_{+1 (+ 2.50%)}	_~	_~	_{p=0.001 n=6}
_Symbols	_380,455	_379,261	_{-1,194 (- 0.31%)}	_~	_~	_{p=0.001 n=6}
_Types	_166,708	_165,539	_{-1,169 (- 0.70%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{540,399k (± 0.01%)}	_{539,428k (± 0.02%)}	_{-971k (- 0.18%)}	_539,215k	_539,551k	_{p=0.005 n=6}
_{Parse Time}	_{4.68s (± 0.37%)}	_{4.68s (± 0.43%)}	_~	_4.66s	_4.71s	_{p=0.682 n=6}
_{Bind Time}	_{2.03s (± 1.00%)}	_{2.04s (± 1.63%)}	_~	_1.99s	_2.07s	_{p=0.677 n=6}
_{Check Time}	_{22.97s (± 0.27%)}	_{22.92s (± 0.39%)}	_~	_22.82s	_23.05s	_{p=0.295 n=6}
_{Emit Time}	_{0.00s (±244.70%)}	_0.00s	_~	_~	_~	_{p=0.405 n=6}
_{Total Time}	_{29.69s (± 0.24%)}	_{29.64s (± 0.30%)}	_~	_29.50s	_29.75s	_{p=0.369 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₃₀	₃₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_690,447	_690,412	_{-35 (- 0.01%)}	_~	_~	_{p=0.001 n=6}
_Types	_208,639	_208,767	_{+128 (+ 0.06%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{586,297k (± 0.01%)}	_{586,450k (± 0.02%)}	_{+153k (+ 0.03%)}	_586,293k	_586,537k	_{p=0.025 n=6}
_{Parse Time}	_{4.16s (± 0.67%)}	_{4.18s (± 0.94%)}	_~	_4.15s	_4.26s	_{p=0.225 n=6}
_{Bind Time}	_{1.42s (± 1.31%)}	_{1.39s (± 1.08%)}	_~	_1.38s	_1.42s	_{p=0.050 n=6}
_{Check Time}	_{21.07s (± 1.75%)}	_{20.67s (± 1.69%)}	_{-0.40s (- 1.91%)}	_20.46s	_21.38s	_{p=0.045 n=6}
_{Emit Time}	_{0.00s (±244.70%)}	_{0.00s (±154.76%)}	_~	_0.00s	_0.01s	_{p=0.595 n=6}
_{Total Time}	_{26.65s (± 1.43%)}	_{26.25s (± 1.48%)}	_~	_26.02s	_27.04s	_{p=0.078 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 · 2025-12-02T19:06:26Z

@jakebailey Here are the results of running the top 400 repos with tsc comparing main and refs/pull/53017/merge:

Everything looks good!

Andarist · 2025-12-05T11:31:02Z

As to the webpack break - I think it's acceptable, see my write up about it here

…ties-of-reverse-mapped-types

weswigham and others added 7 commits December 21, 2017 14:52

Infer type parameters from indexes on those parameters

3451575

Greatly simplify partial inference type instantiation through use of …

f5b208c

…an alias in lib

Add many more tests showing current behaviors

ba064ac

Discriminate partial inferences if not complete enough to satisfy con…

93afc10

…straint

Move case to prefered location

49e1961

Small refactor to reduce how many comparisons are performed

96772e5

Infer reverse mapped types based on inferences made for its concrete …

2e0c635

…properties

typescript-bot added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Feb 28, 2023

Andarist commented Feb 28, 2023

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Andarist commented Feb 28, 2023

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Andarist commented Feb 28, 2023

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Andarist commented Feb 28, 2023

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sandersn requested review from ahejlsberg and weswigham March 9, 2023 18:07

typescript-bot removed the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Mar 9, 2023

sandersn assigned ahejlsberg Mar 9, 2023

typescript-bot added the For Backlog Bug PRs that fix a backlog bug label Mar 9, 2023

weswigham requested changes Mar 14, 2023

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Andarist added 7 commits April 17, 2023 19:15

Merge remote-tracking branch 'origin/main' into infer-concrete-proper…

7b8cf10

…ties-of-reverse-mapped-types

Merge remote-tracking branch 'weswigham/index-combined-inferences' in…

e7e4e70

…to infer-concrete-properties-of-reverse-mapped-types-with-wes

update baselines, note: some are broken

d0e8b8b

use new inference.indexes in reverse mapped type inference

e5d0ea8

update reverse mapped baseline

b0b2fcb

Call getActualTypeVariable appropriately to fix inference for a tup…

7fe118a

…le reverse mapped type

Avoid inferring an index under InferencePriority.NakedTypeVariable

50e6a0c

Andarist requested a review from weswigham April 18, 2023 11:52

Andarist commented Apr 18, 2023

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Andarist changed the title ~~Infer reverse mapped types based on inferences made for its concrete properties~~ Infer type parameters from indexes on those parameters Apr 19, 2023

always discard aggregate inference that is not assignable to the cons…

4febb9c

…traint

Andarist added 3 commits December 1, 2025 18:59

experiment with eraseSelfMapper

2b580c8

experiment further

a390703

drop unused code

15eda09

Andarist added 5 commits December 2, 2025 09:42

discard never aggregate inferences

e3f6b43

prefer default

1911406

Merge remote-tracking branch 'origin/main' into infer-concrete-proper…

20d6feb

…ties-of-reverse-mapped-types

change condition for indexes gathering

a554bbf

simplify test

22ddecc

refactor

ced3cc1

Andarist force-pushed the infer-concrete-properties-of-reverse-mapped-types branch from d603445 to ced3cc1 Compare December 2, 2025 18:40

Andarist added 2 commits December 3, 2025 09:02

remove PartialInference

a09f410

add tests

7bc77f1

RyanCavanaugh mentioned this pull request Dec 4, 2025

Improve reverse mapped types inference by creating candidates from concrete index types #51612

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Merge remote-tracking branch 'origin/main' into infer-concrete-proper…

097b8e6

…ties-of-reverse-mapped-types

Andarist mentioned this pull request Jan 2, 2026

Experiment: Quantified Types microsoft/typescript-go#2434

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