Fix a relationship check for partial generic mapped targets by Andarist · Pull Request #62724 · microsoft/TypeScript

Andarist · 2025-11-05T22:27:18Z

Andarist · 2025-11-05T22:32:52Z

src/compiler/checker.ts

                const templateType = getTemplateTypeFromMappedType(target);
-                const modifiers = getMappedTypeModifiers(target);
-                if (!(modifiers & MappedTypeModifiers.ExcludeOptional)) {
+                const combinedOptionality = getCombinedMappedTypeOptionality(target);


This is an extra fix that is not needed for the original repro. I just noticed that those 2 behaved differently: WithNumber<Partial<Record<keyof T, any>>> vs Partial<WithNumber<Record<keyof T, any>>>. So to fix that ordering difference, I included this change here

Andarist · 2025-11-05T22:33:38Z

src/compiler/checker.ts

-                                if (result = isRelatedTo(source, (nonNullComponent as IndexedAccessType).objectType, RecursionFlags.Target, reportErrors)) {
-                                    return result;
-                                }
+                            if (!keysRemapped && nonNullComponent.flags & TypeFlags.IndexedAccess && (nonNullComponent as IndexedAccessType).indexType === typeParameter && (result = isRelatedTo(source, (nonNullComponent as IndexedAccessType).objectType, RecursionFlags.Target, reportErrors))) {


this simply allows the code to take the slow path if the fast path doesnt return Ternary.True

RyanCavanaugh · 2025-11-06T16:33:31Z

@typescript-bot test it

typescript-bot · 2025-11-06T16:33:37Z

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 · 2025-11-06T16:57:52Z

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

Everything looks the same!

You can check the log here.

typescript-bot · 2025-11-06T17:03:12Z

@RyanCavanaugh Here are the results of running the user tests with tsc comparing main and refs/pull/62724/merge:

There were infrastructure failures potentially unrelated to your change:

1 instance of "Git clone failed"

Otherwise...

Everything looks good!

typescript-bot · 2025-11-06T17:25:50Z

@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	₁	₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_62,370	_62,370	_~	_~	_~	_{p=1.000 n=6}
_Types	_50,386	_50,386	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{194,506k (± 0.99%)}	_{195,147k (± 0.92%)}	_~	_192,669k	_196,383k	_{p=0.230 n=6}
_{Parse Time}	_{1.31s (± 0.42%)}	_{1.30s (± 0.42%)}	_~	_1.30s	_1.31s	_{p=1.000 n=6}
_{Bind Time}	_0.72s	_{0.72s (± 0.71%)}	_~	_0.72s	_0.73s	_{p=0.174 n=6}
_{Check Time}	_{9.88s (± 0.46%)}	_{9.87s (± 0.29%)}	_~	_9.82s	_9.90s	_{p=0.935 n=6}
_{Emit Time}	_{2.74s (± 0.73%)}	_{2.76s (± 0.30%)}	_~	_2.75s	_2.77s	_{p=0.170 n=6}
_{Total Time}	_{14.65s (± 0.27%)}	_{14.65s (± 0.16%)}	_~	_14.61s	_14.68s	_{p=0.625 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_956,047	_956,047	_~	_~	_~	_{p=1.000 n=6}
_Types	_415,881	_415,883	_{+2 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{1,255,052k (± 0.00%)}	_{1,255,006k (± 0.00%)}	_~	_1,254,932k	_1,255,066k	_{p=0.230 n=6}
_{Parse Time}	_{6.55s (± 0.59%)}	_{6.56s (± 0.72%)}	_~	_6.48s	_6.61s	_{p=0.573 n=6}
_{Bind Time}	_{1.88s (± 0.27%)}	_{1.88s (± 0.27%)}	_~	_1.88s	_1.89s	_{p=1.000 n=6}
_{Check Time}	_{32.27s (± 0.19%)}	_{32.24s (± 0.39%)}	_~	_32.08s	_32.37s	_{p=1.000 n=6}
_{Emit Time}	_{14.93s (± 0.20%)}	_{14.95s (± 0.46%)}	_~	_14.86s	_15.06s	_{p=0.686 n=6}
_{Total Time}	_{55.63s (± 0.12%)}	_{55.63s (± 0.28%)}	_~	_55.49s	_55.90s	_{p=0.629 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_552,568	_552,568	_~	_~	_~	_{p=1.000 n=6}
_Types	₈₉	₈₉	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{827,086k (± 0.00%)}	_{827,070k (± 0.00%)}	_~	_827,052k	_827,097k	_{p=0.093 n=6}
_{Parse Time}	_{8.36s (± 0.18%)}	_{8.36s (± 0.14%)}	_~	_8.35s	_8.38s	_{p=0.563 n=6}
_{Bind Time}	_{2.19s (± 0.45%)}	_{2.18s (± 0.47%)}	_~	_2.17s	_2.19s	_{p=0.386 n=6}
_{Check Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Emit Time}	_0.28s	_{0.28s (± 1.47%)}	_~	_0.27s	_0.28s	_{p=0.405 n=6}
_{Total Time}	_{10.82s (± 0.20%)}	_{10.82s (± 0.15%)}	_~	_10.80s	_10.84s	_{p=1.000 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,237,277	_1,237,277	_~	_~	_~	_{p=1.000 n=6}
_Types	_259,883	_259,883	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,365,184k (± 0.02%)}	_{2,486,621k (±11.94%)}	_~	_2,365,055k	_3,093,260k	_{p=0.378 n=6}
_{Parse Time}	_{5.13s (± 1.31%)}	_{5.15s (± 1.14%)}	_~	_5.07s	_5.20s	_{p=0.809 n=6}
_{Bind Time}	_{1.77s (± 1.35%)}	_{1.76s (± 0.95%)}	_~	_1.73s	_1.78s	_{p=0.720 n=6}
_{Check Time}	_{35.22s (± 0.12%)}	_{35.20s (± 0.44%)}	_~	_35.05s	_35.50s	_{p=0.230 n=6}
_{Emit Time}	_{3.01s (± 1.32%)}	_{3.02s (± 1.02%)}	_~	_2.99s	_3.07s	_{p=0.377 n=6}
_{Total Time}	_{45.15s (± 0.14%)}	_{45.13s (± 0.40%)}	_~	_45.00s	_45.47s	_{p=0.336 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,237,277	_1,237,277	_~	_~	_~	_{p=1.000 n=6}
_Types	_259,883	_259,883	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{3,038,991k (± 9.72%)}	_{3,159,447k (± 0.01%)}	_~	_3,158,977k	_3,159,837k	_{p=0.936 n=6}
_{Parse Time}	_{6.80s (± 1.49%)}	_{6.87s (± 0.33%)}	_{+0.07s (+ 1.05%)}	_6.84s	_6.91s	_{p=0.044 n=6}
_{Bind Time}	_{2.17s (± 0.86%)}	_{2.13s (± 0.71%)}	_{-0.03s (- 1.54%)}	_2.11s	_2.15s	_{p=0.023 n=6}
_{Check Time}	_{42.81s (± 0.52%)}	_{42.82s (± 0.18%)}	_~	_42.66s	_42.88s	_{p=0.575 n=6}
_{Emit Time}	_{3.49s (± 2.40%)}	_{3.56s (± 2.48%)}	_~	_3.41s	_3.66s	_{p=0.173 n=6}
_{Total Time}	_{55.25s (± 0.54%)}	_{55.38s (± 0.23%)}	_~	_55.19s	_55.51s	_{p=0.471 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_262,522	_262,522	_~	_~	_~	_{p=1.000 n=6}
_Types	_104,048	_104,048	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{441,148k (± 0.25%)}	_{440,713k (± 0.00%)}	_~	_440,678k	_440,736k	_{p=0.689 n=6}
_{Parse Time}	_{3.52s (± 0.91%)}	_{3.51s (± 0.25%)}	_~	_3.50s	_3.52s	_{p=0.566 n=6}
_{Bind Time}	_{1.32s (± 0.89%)}	_{1.32s (± 0.91%)}	_~	_1.31s	_1.34s	_{p=0.502 n=6}
_{Check Time}	_{18.98s (± 0.63%)}	_{18.99s (± 0.30%)}	_~	_18.90s	_19.07s	_{p=0.686 n=6}
_{Emit Time}	_{1.52s (± 1.02%)}	_{1.53s (± 1.37%)}	_~	_1.51s	_1.56s	_{p=0.460 n=6}
_{Total Time}	_{25.34s (± 0.63%)}	_{25.35s (± 0.25%)}	_~	_25.25s	_25.44s	_{p=0.689 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₇₂	₇₂	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_225,386	_225,386	_~	_~	_~	_{p=1.000 n=6}
_Types	_94,304	_94,329	_{+25 (+ 0.03%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{370,120k (± 0.03%)}	_{370,069k (± 0.06%)}	_~	_369,927k	_370,458k	_{p=0.230 n=6}
_{Parse Time}	_{2.85s (± 0.73%)}	_{2.84s (± 0.80%)}	_~	_2.82s	_2.88s	_{p=0.684 n=6}
_{Bind Time}	_{1.60s (± 0.94%)}	_{1.62s (± 0.64%)}	_~	_1.61s	_1.63s	_{p=0.078 n=6}
_{Check Time}	_{16.51s (± 0.37%)}	_{16.52s (± 0.39%)}	_~	_16.42s	_16.60s	_{p=0.936 n=6}
_{Emit Time}	_0.00s	_{0.00s (±244.70%)}	_~	_0.00s	_0.01s	_{p=0.405 n=6}
_{Total Time}	_{20.96s (± 0.33%)}	_{20.98s (± 0.34%)}	_~	_20.92s	_21.08s	_{p=0.809 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_4,018,300	_4,018,463	_{+163 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_1,260,803	_1,261,056	_{+253 (+ 0.02%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,800,117k (± 0.01%)}	_{3,800,403k (± 0.00%)}	_~	_3,800,227k	_3,800,529k	_{p=0.093 n=6}
_{Parse Time}	_{15.53s (± 0.51%)}	_{15.58s (± 0.28%)}	_~	_15.51s	_15.63s	_{p=0.199 n=6}
_{Bind Time}	_{5.10s (± 2.40%)}	_{5.07s (± 2.76%)}	_~	_4.95s	_5.34s	_{p=0.628 n=6}
_{Check Time}	_{104.56s (± 2.54%)}	_{107.41s (± 3.02%)}	_~	_101.59s	_111.45s	_{p=0.128 n=6}
_{Emit Time}	_{41.42s (±14.97%)}	_{39.90s (±16.53%)}	_~	_31.42s	_48.44s	_{p=0.689 n=6}
_{Total Time}	_{166.61s (± 2.21%)}	_{167.96s (± 3.53%)}	_~	_160.52s	_177.63s	_{p=0.810 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₄₀	₄₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_379,170	_379,170	_~	_~	_~	_{p=1.000 n=6}
_Types	_166,358	_166,358	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{537,920k (± 0.04%)}	_{537,995k (± 0.02%)}	_~	_537,884k	_538,149k	_{p=0.575 n=6}
_{Parse Time}	_{4.60s (± 0.65%)}	_{4.62s (± 0.88%)}	_~	_4.56s	_4.68s	_{p=0.332 n=6}
_{Bind Time}	_{1.94s (± 1.37%)}	_{1.94s (± 0.60%)}	_~	_1.93s	_1.96s	_{p=0.739 n=6}
_{Check Time}	_{22.71s (± 1.24%)}	_{22.61s (± 0.69%)}	_~	_22.41s	_22.82s	_{p=0.688 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{29.25s (± 1.02%)}	_{29.17s (± 0.57%)}	_~	_28.99s	_29.43s	_{p=0.748 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₃₀	₃₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_690,485	_690,485	_~	_~	_~	_{p=1.000 n=6}
_Types	_208,757	_208,757	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{586,711k (± 0.03%)}	_{586,518k (± 0.03%)}	_~	_586,349k	_586,694k	_{p=0.093 n=6}
_{Parse Time}	_{4.17s (± 0.44%)}	_{4.18s (± 0.73%)}	_~	_4.12s	_4.21s	_{p=0.459 n=6}
_{Bind Time}	_{1.34s (± 0.61%)}	_{1.36s (± 0.86%)}	_{+0.02s (+ 1.62%)}	_1.34s	_1.37s	_{p=0.014 n=6}
_{Check Time}	_{20.40s (± 1.55%)}	_{20.62s (± 1.87%)}	_~	_20.25s	_21.01s	_{p=0.686 n=6}
_{Emit Time}	_{0.00s (±154.76%)}	_{0.01s (±109.43%)}	_~	_0.00s	_0.01s	_{p=0.640 n=6}
_{Total Time}	_{25.91s (± 1.22%)}	_{26.17s (± 1.38%)}	_~	_25.82s	_26.57s	_{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 · 2025-11-06T17:57:48Z

@RyanCavanaugh Here are the results of running the top 400 repos with tsc comparing main and refs/pull/62724/merge:

Everything looks good!

russelldavis · 2025-11-12T20:02:59Z

@RyanCavanaugh should #62717 be reopened, given this PR?

…rget-fast-path

typescript-bot · 2026-03-24T21:22:52Z

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

Fix a relationship check for partial generic mapped targets

856a579

github-project-automation bot added this to PR Backlog Nov 5, 2025

github-project-automation bot moved this to Not started in PR Backlog Nov 5, 2025

typescript-bot added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Nov 5, 2025

Andarist mentioned this pull request Nov 5, 2025

Generic constraint fails with Partial<Record<keyof T, any>> but works with { [K in keyof T]?: any } #62717

Closed

Andarist commented Nov 5, 2025

View reviewed changes

Andarist added 2 commits November 17, 2025 12:57

Merge remote-tracking branch 'origin/main' into fix/generic-mapped-ta…

2f7d409

…rget-fast-path

add test

f68bcc3

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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Fix a relationship check for partial generic mapped targets#62724

Fix a relationship check for partial generic mapped targets#62724
Andarist wants to merge 3 commits intomicrosoft:mainfrom
Andarist:fix/generic-mapped-target-fast-path

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