Compare optional property flag when comparing against discriminant properties under `exactOptionalPropertyTypes` by Andarist · Pull Request #61682 · microsoft/TypeScript

Andarist · 2025-05-09T17:36:43Z

…operties under `exactOptionalPropertyTypes`

Copilot

Pull Request Overview

This PR fixes an issue (#61678) in which optional property flags are compared incorrectly against discriminant properties when the compiler flag exactOptionalPropertyTypes is enabled. Key changes include updated test cases that expect errors in union discriminant assignments and a modification of the comparison logic in the checker.

Reviewed Changes

Copilot reviewed 3 out of 15 changed files in this pull request and generated 1 comment.

File	Description
tests/cases/compiler/unionRelationshipCheckPasses3.ts	New test case to verify union assignment errors with different optional property flags
tests/cases/compiler/unionRelationshipCheckPasses2.ts	Additional test confirming error handling with union discriminants
src/compiler/checker.ts	Updated property comparison logic to consider exactOptionalPropertyTypes when checking optional properties

Files not reviewed (12)

tests/baselines/reference/unionRelationshipCheckPasses2(exactoptionalpropertytypes=false).errors.txt: Language not supported
tests/baselines/reference/unionRelationshipCheckPasses2(exactoptionalpropertytypes=false).symbols: Language not supported
tests/baselines/reference/unionRelationshipCheckPasses2(exactoptionalpropertytypes=false).types: Language not supported
tests/baselines/reference/unionRelationshipCheckPasses2(exactoptionalpropertytypes=true).errors.txt: Language not supported
tests/baselines/reference/unionRelationshipCheckPasses2(exactoptionalpropertytypes=true).symbols: Language not supported
tests/baselines/reference/unionRelationshipCheckPasses2(exactoptionalpropertytypes=true).types: Language not supported
tests/baselines/reference/unionRelationshipCheckPasses3(exactoptionalpropertytypes=false).errors.txt: Language not supported
tests/baselines/reference/unionRelationshipCheckPasses3(exactoptionalpropertytypes=false).symbols: Language not supported
tests/baselines/reference/unionRelationshipCheckPasses3(exactoptionalpropertytypes=false).types: Language not supported
tests/baselines/reference/unionRelationshipCheckPasses3(exactoptionalpropertytypes=true).errors.txt: Language not supported
tests/baselines/reference/unionRelationshipCheckPasses3(exactoptionalpropertytypes=true).symbols: Language not supported
tests/baselines/reference/unionRelationshipCheckPasses3(exactoptionalpropertytypes=true).types: Language not supported

src/compiler/checker.ts

Andarist · 2025-05-09T17:40:48Z

src/compiler/checker.ts

                        if (sourceProperty === targetProperty) continue;
                        // We compare the source property to the target in the context of a single discriminant type.
-                        const related = propertyRelatedTo(source, target, sourceProperty, targetProperty, _ => combination[i], /*reportErrors*/ false, IntersectionState.None, /*skipOptional*/ strictNullChecks || relation === comparableRelation);
+                        const related = propertyRelatedTo(source, target, sourceProperty, targetProperty, _ => combination[i], /*reportErrors*/ false, IntersectionState.None, /*skipOptional*/ strictNullChecks && !exactOptionalPropertyTypes || relation === comparableRelation);


skipOptional got introduced in #38101 . According to that PR's description its main goal is to align with this principle:

an optional undefined is the same as an undefined field in everything except what we require be written in declarations

But that's not true under exactOptionalPropertyTypes. So the easiest fix to this issue seems to be to just pass skipOptional === false when exactOptionalPropertyTypes is enabled.

RyanCavanaugh · 2025-05-09T17:42:49Z

@typescript-bot test it

typescript-bot · 2025-05-09T17:42:54Z

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 · 2025-05-09T18:05:03Z

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

Everything looks the same!

You can check the log here.

typescript-bot · 2025-05-09T18:06:27Z

@RyanCavanaugh Here are the results of running the user tests with tsc comparing main and refs/pull/61682/merge:

Everything looks good!

typescript-bot · 2025-05-09T18:30:14Z

@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	_62,390	_62,390	_~	_~	_~	_{p=1.000 n=6}
_Types	_50,395	_50,395	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{194,305k (± 0.99%)}	_{192,970k (± 0.01%)}	_~	_192,947k	_193,005k	_{p=0.173 n=6}
_{Parse Time}	_{1.30s (± 0.79%)}	_{1.31s (± 0.39%)}	_~	_1.31s	_1.32s	_{p=0.069 n=6}
_{Bind Time}	_0.73s	_0.73s	_~	_~	_~	_{p=1.000 n=6}
_{Check Time}	_{9.75s (± 0.24%)}	_{9.76s (± 0.14%)}	_~	_9.74s	_9.78s	_{p=0.677 n=6}
_{Emit Time}	_{2.73s (± 0.43%)}	_{2.74s (± 0.68%)}	_~	_2.72s	_2.77s	_{p=0.222 n=6}
_{Total Time}	_{14.52s (± 0.20%)}	_{14.54s (± 0.18%)}	_~	_14.51s	_14.57s	_{p=0.126 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₅₆	₅₆	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_949,240	_949,240	_~	_~	_~	_{p=1.000 n=6}
_Types	_411,065	_411,065	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{1,225,084k (± 0.00%)}	_{1,225,100k (± 0.00%)}	_~	_1,225,063k	_1,225,133k	_{p=0.575 n=6}
_{Parse Time}	_{6.65s (± 0.70%)}	_{6.64s (± 0.79%)}	_~	_6.56s	_6.68s	_{p=0.807 n=6}
_{Bind Time}	_{1.88s (± 0.48%)}	_{1.88s (± 0.29%)}	_~	_1.88s	_1.89s	_{p=0.341 n=6}
_{Check Time}	_{31.94s (± 0.28%)}	_{31.87s (± 0.29%)}	_~	_31.75s	_32.00s	_{p=0.298 n=6}
_{Emit Time}	_{15.23s (± 0.39%)}	_{15.24s (± 0.20%)}	_~	_15.19s	_15.27s	_{p=0.571 n=6}
_{Total Time}	_{55.70s (± 0.16%)}	_{55.63s (± 0.22%)}	_~	_55.39s	_55.74s	_{p=0.423 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,439,920	_2,439,920	_~	_~	_~	_{p=1.000 n=6}
_Types	_872,553	_872,553	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,448,218k (± 0.00%)}	_{2,448,236k (± 0.00%)}	_~	_2,448,170k	_2,448,307k	_{p=0.689 n=6}
_{Parse Time}	_{8.76s (± 0.47%)}	_{8.75s (± 0.31%)}	_~	_8.72s	_8.79s	_{p=0.872 n=6}
_{Bind Time}	_{2.22s (± 0.62%)}	_{2.21s (± 0.48%)}	_~	_2.19s	_2.22s	_{p=0.160 n=6}
_{Check Time}	_{72.33s (± 0.78%)}	_{72.64s (± 0.44%)}	_~	_72.08s	_73.04s	_{p=0.377 n=6}
_{Emit Time}	_{0.30s (± 2.52%)}	_{0.31s (± 3.79%)}	_~	_0.29s	_0.32s	_{p=0.136 n=6}
_{Total Time}	_{83.60s (± 0.63%)}	_{83.90s (± 0.39%)}	_~	_83.34s	_84.35s	_{p=0.173 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,228,052	_1,228,052	_~	_~	_~	_{p=1.000 n=6}
_Types	_267,262	_267,262	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,360,607k (± 0.02%)}	_{2,360,755k (± 0.03%)}	_~	_2,359,481k	_2,361,666k	_{p=0.689 n=6}
_{Parse Time}	_{5.25s (± 0.53%)}	_{5.21s (± 1.45%)}	_~	_5.11s	_5.30s	_{p=0.575 n=6}
_{Bind Time}	_{1.80s (± 0.67%)}	_{1.80s (± 1.11%)}	_~	_1.77s	_1.82s	_{p=0.934 n=6}
_{Check Time}	_{35.44s (± 0.42%)}	_{35.52s (± 0.53%)}	_~	_35.31s	_35.73s	_{p=0.297 n=6}
_{Emit Time}	_{3.01s (± 2.58%)}	_{3.06s (± 4.33%)}	_~	_2.94s	_3.32s	_{p=0.471 n=6}
_{Total Time}	_{45.50s (± 0.48%)}	_{45.61s (± 0.46%)}	_~	_45.38s	_45.85s	_{p=0.471 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,228,052	_1,228,052	_~	_~	_~	_{p=1.000 n=6}
_Types	_267,262	_267,262	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{3,038,092k (± 9.78%)}	_{2,942,598k (±11.54%)}	_~	_2,428,969k	_3,160,662k	_{p=0.936 n=6}
_{Parse Time}	_{6.91s (± 1.35%)}	_{6.94s (± 0.78%)}	_~	_6.89s	_7.02s	_{p=0.873 n=6}
_{Bind Time}	_{2.18s (± 1.63%)}	_{2.18s (± 1.90%)}	_~	_2.13s	_2.24s	_{p=0.688 n=6}
_{Check Time}	_{42.91s (± 0.51%)}	_{42.80s (± 1.04%)}	_~	_42.00s	_43.22s	_{p=1.000 n=6}
_{Emit Time}	_{3.46s (± 1.46%)}	_{3.54s (± 2.21%)}	_~	_3.41s	_3.62s	_{p=0.093 n=6}
_{Total Time}	_{55.47s (± 0.48%)}	_{55.46s (± 0.83%)}	_~	_54.64s	_55.99s	_{p=0.936 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_263,419	_263,419	_~	_~	_~	_{p=1.000 n=6}
_Types	_107,098	_107,098	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{441,719k (± 0.01%)}	_{441,751k (± 0.01%)}	_~	_441,679k	_441,854k	_{p=0.378 n=6}
_{Parse Time}	_{3.55s (± 0.70%)}	_{3.55s (± 1.28%)}	_~	_3.51s	_3.62s	_{p=0.936 n=6}
_{Bind Time}	_{1.32s (± 1.27%)}	_{1.33s (± 1.16%)}	_~	_1.30s	_1.34s	_{p=0.186 n=6}
_{Check Time}	_{19.07s (± 0.16%)}	_{19.05s (± 0.41%)}	_~	_18.94s	_19.15s	_{p=0.936 n=6}
_{Emit Time}	_{1.53s (± 1.51%)}	_{1.54s (± 1.14%)}	_~	_1.51s	_1.56s	_{p=0.808 n=6}
_{Total Time}	_{25.46s (± 0.22%)}	_{25.47s (± 0.43%)}	_~	_25.35s	_25.65s	_{p=0.936 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₇₁	₇₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_225,981	_225,981	_~	_~	_~	_{p=1.000 n=6}
_Types	_94,356	_94,356	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{371,359k (± 0.05%)}	_{371,340k (± 0.02%)}	_~	_371,285k	_371,442k	_{p=0.298 n=6}
_{Parse Time}	_{2.90s (± 0.71%)}	_{2.86s (± 1.67%)}	_~	_2.81s	_2.93s	_{p=0.145 n=6}
_{Bind Time}	_{1.60s (± 1.75%)}	_{1.59s (± 1.47%)}	_~	_1.57s	_1.64s	_{p=0.932 n=6}
_{Check Time}	_{16.44s (± 0.17%)}	_{16.44s (± 0.15%)}	_~	_16.41s	_16.48s	_{p=1.000 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{20.94s (± 0.23%)}	_{20.90s (± 0.28%)}	_~	_20.81s	_20.97s	_{p=0.225 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₅₁	₅₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_3,424,652	_3,424,652	_~	_~	_~	_{p=1.000 n=6}
_Types	_1,155,330	_1,155,330	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{3,475,455k (± 0.01%)}	_{3,475,635k (± 0.01%)}	_~	_3,475,406k	_3,475,985k	_{p=0.470 n=6}
_{Parse Time}	_{14.73s (± 0.58%)}	_{14.76s (± 0.70%)}	_~	_14.68s	_14.96s	_{p=0.687 n=6}
_{Bind Time}	_{4.78s (± 0.34%)}	_{4.77s (± 0.85%)}	_~	_4.72s	_4.82s	_{p=0.685 n=6}
_{Check Time}	_{96.77s (± 3.52%)}	_{93.61s (± 0.24%)}	_~	_93.32s	_93.87s	_{p=0.066 n=6}
_{Emit Time}	_{30.60s (± 2.60%)}	_{29.94s (± 0.87%)}	_~	_29.62s	_30.35s	_{p=0.173 n=6}
_{Total Time}	_{146.89s (± 2.84%)}	_{143.08s (± 0.29%)}	_~	_142.55s	_143.69s	_{p=0.109 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_317,848	_317,848	_~	_~	_~	_{p=1.000 n=6}
_Types	_140,485	_140,485	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{473,083k (± 0.02%)}	_{473,127k (± 0.02%)}	_~	_473,016k	_473,231k	_{p=0.378 n=6}
_{Parse Time}	_{5.16s (± 0.61%)}	_{5.10s (± 1.34%)}	_~	_5.02s	_5.18s	_{p=0.170 n=6}
_{Bind Time}	_{2.25s (± 1.46%)}	_{2.28s (± 0.95%)}	_~	_2.26s	_2.31s	_{p=0.075 n=6}
_{Check Time}	_{25.96s (± 0.50%)}	_{26.00s (± 0.40%)}	_~	_25.87s	_26.16s	_{p=0.375 n=6}
_{Emit Time}	_0.00s	_{0.00s (±244.70%)}	_~	_0.00s	_0.01s	_{p=0.405 n=6}
_{Total Time}	_{33.38s (± 0.37%)}	_{33.38s (± 0.39%)}	_~	_33.15s	_33.53s	_{p=0.630 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_570,733	_570,733	_~	_~	_~	_{p=1.000 n=6}
_Types	_191,446	_191,446	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{501,314k (± 0.01%)}	_{501,319k (± 0.01%)}	_~	_501,200k	_501,373k	_{p=0.936 n=6}
_{Parse Time}	_{4.33s (± 0.38%)}	_{4.32s (± 0.79%)}	_~	_4.26s	_4.35s	_{p=0.372 n=6}
_{Bind Time}	_{1.53s (± 0.69%)}	_{1.52s (± 0.77%)}	_~	_1.51s	_1.54s	_{p=0.619 n=6}
_{Check Time}	_{24.95s (± 0.50%)}	_{24.96s (± 0.27%)}	_~	_24.90s	_25.09s	_{p=1.000 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{30.81s (± 0.43%)}	_{30.80s (± 0.22%)}	_~	_30.71s	_30.91s	_{p=1.000 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 · 2025-05-09T19:27:01Z

@RyanCavanaugh Here are the results of running the top 400 repos with tsc comparing main and refs/pull/61682/merge:

Everything looks good!

…oDiscriminatedType

Compare optional property flag when comparing against discriminant pr…

7d5097b

…operties under `exactOptionalPropertyTypes`

Copilot AI review requested due to automatic review settings May 9, 2025 17:36

github-project-automation bot added this to PR Backlog May 9, 2025

github-project-automation bot moved this to Not started in PR Backlog May 9, 2025

typescript-bot assigned ahejlsberg May 9, 2025

typescript-bot added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label May 9, 2025

Copilot AI reviewed May 9, 2025

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src/compiler/checker.ts Show resolved Hide resolved

Andarist commented May 9, 2025

View reviewed changes

Andarist force-pushed the fix/eopt-typeRelatedToDiscriminatedType branch from 5ecc087 to 7d5097b Compare May 19, 2025 09:43

Merge remote-tracking branch 'origin/main' into fix/eopt-typeRelatedT…

05f69c2

…oDiscriminatedType

Andarist force-pushed the fix/eopt-typeRelatedToDiscriminatedType branch from 27d8240 to 05f69c2 Compare December 5, 2025 18:55

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Compare optional property flag when comparing against discriminant properties under `exactOptionalPropertyTypes`#61682

Compare optional property flag when comparing against discriminant properties under `exactOptionalPropertyTypes`#61682
Andarist wants to merge 2 commits intomicrosoft:mainfrom
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