Allow accessing named declared members during a type's resolution by ahejlsberg · Pull Request #65059 · microsoft/TypeScript

Anders Hejlsberg (ahejlsberg) · 2026-10-30T15:53:13Z

This is similar to #64688, but works with the lazy member resolution introduced in #64915 and also ensures that inherited declared members can be accessed during a type's resolution. Closes #64688.

Fixes #64605.

Anders Hejlsberg (ahejlsberg) · 2026-10-30T15:53:31Z

TypeScript Bot (@typescript-bot) test it

typescript-automation · 2026-10-30T15:53:36Z

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

Copilot

🟡 Changes recommended

Recursive inherited-property lookups can lose cached symbols after stack reallocation and trigger circular resolution before reaching later base declarations.

2 open issues

What changed in this PR

This PR lets the native TypeScript checker access declared and inherited named members while a type’s member layout is still resolving. It adapts the approach from #64688 to lazy member resolution, addressing the Zod circularity regression in #64605.

Changes:

Tracks resolving object types and carries early-resolved properties into their completed lazy layouts.
Adds regression coverage for recursive property access and inherited declared members.
Updates diagnostic baselines to remove circularity and excessive-instantiation errors.

File	Description
`tsc/testdata/tests/cases/compiler/circularDeclaredPropertyAccess.ts`	Adds Zod and inherited-member regression cases.
`tsc/testdata/baselines/reference/compiler/sharedMemberLayoutThisIntersectionBase.errors.txt`	Removes excessive-instantiation diagnostics.
`tsc/testdata/baselines/reference/compiler/mutuallyRecursiveInference.errors.txt`	Removes a circular-instantiation diagnostic.
`tsc/testdata/baselines/reference/compiler/circularDeclaredPropertyAccess.types`	Records inferred types for the new cases.
`tsc/testdata/baselines/reference/compiler/circularDeclaredPropertyAccess.symbols`	Records symbols for the new cases.
`tsc/internal/checker/checker.go`	Enables property lookup during member resolution and preserves resolved symbols.

_{Review effort: Balanced}

Anders Hejlsberg (ahejlsberg) · 2026-10-30T19:13:28Z

+					resolved = c.instantiateSymbol(symbol, r.mapper)
+				} else {
+					for _, baseType := range r.baseTypes {
+						if resolved = c.getPropertyOfTypeEx(baseType, name, true, false); resolved != nil {


This is intended. When D extends M<D>, Y we need to fully resolve M<D> in order to know whether it declares a q or whether q is inherited from Y. If that resolution causes a circularity, that circularity will eventually be caught elsewhere.

Anders Hejlsberg (ahejlsberg) · 2026-10-30T19:13:54Z

+						}
+					}
+				}
+				if resolved != nil {


Yeah, unlikely, but possible. Will fix.

typescript-automation · 2026-10-30T16:25:47Z

Hey Anders Hejlsberg (@ahejlsberg), the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

typescript-automation · 2026-10-30T16:37:58Z

Anders Hejlsberg (@ahejlsberg) Here are the results of running the user tests with tsc comparing baseline and pr:

Everything looks good!

typescript-automation · 2026-10-30T16:55:22Z

Anders Hejlsberg (@ahejlsberg)
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 - native}
_Errors	₄₁	₄₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_88,466	_88,466	_~	_~	_~	_{p=1.000 n=20}
_Types	_79,607	_79,607	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{104,107k (± 0.03%)}	_{104,061k (± 0.03%)}	_{-46k (- 0.04%)}	_103,940k	_104,166k	_{p=0.028 n=20}
_{Memory Allocs}	_{1,262,326 (± 0.01%)}	_{1,262,431 (± 0.01%)}	_~	_1,261,844	_1,262,993	_{p=0.114 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.023s (± 2.24%)}	_{0.023s (± 2.75%)}	_~	_0.020s	_0.025s	_{p=0.831 n=20}
_{Bind Time}	_{0.008s (± 4.50%)}	_{0.008s (± 4.37%)}	_~	_0.007s	_0.010s	_{p=0.677 n=20}
_{Check Time}	_{0.215s (± 0.93%)}	_{0.217s (± 1.19%)}	_~	_0.209s	_0.229s	_{p=0.284 n=20}
_{Emit Time}	_{0.138s (± 1.48%)}	_{0.139s (± 1.71%)}	_~	_0.132s	_0.152s	_{p=0.846 n=20}
_{Total Time}	_{0.388s (± 0.87%)}	_{0.391s (± 0.90%)}	_~	_0.381s	_0.408s	_{p=0.174 n=20}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_{586,579 (± 0.02%)}	_{586,552 (± 0.01%)}	_~	_586,121	_586,782	_{p=0.683 n=20}
_Types	_{241,687 (± 0.00%)}	_{241,687 (± 0.00%)}	_~	_241,683	_241,697	_{p=0.584 n=20}
_{Memory Used}	_{517,760k (± 0.01%)}	_{517,787k (± 0.02%)}	_~	_517,204k	_518,148k	_{p=0.355 n=20}
_{Memory Allocs}	_{7,794,110 (± 0.18%)}	_{7,796,118 (± 0.16%)}	_~	_7,779,053	_7,869,932	_{p=0.820 n=20}
_{Config Time}	_{0.009s (± 1.15%)}	_{0.009s (± 1.15%)}	_~	_0.009s	_0.010s	_{p=1.000 n=20}
_{Parse Time}	_{0.126s (± 3.12%)}	_{0.127s (± 2.10%)}	_~	_0.119s	_0.141s	_{p=0.400 n=20}
_{Bind Time}	_{0.045s (±10.11%)}	_{0.042s (± 7.50%)}	_~	_0.037s	_0.062s	_{p=0.187 n=20}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=20}
_{Emit Time}	_{0.857s (± 1.32%)}	_{0.849s (± 0.89%)}	_~	_0.820s	_0.874s	_{p=0.425 n=20}
_{Total Time}	_{1.050s (± 1.58%)}	_{1.039s (± 1.02%)}	_~	_1.010s	_1.077s	_{p=0.542 n=20}
_{arktype - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_685,920	_685,920	_~	_~	_~	_{p=1.000 n=20}
_Types	_939,467	_939,467	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{495,092k (± 0.01%)}	_{495,086k (± 0.01%)}	_~	_494,912k	_495,308k	_{p=0.774 n=20}
_{Memory Allocs}	_{12,062,855 (± 0.02%)}	_{12,062,335 (± 0.01%)}	_~	_12,058,239	_12,068,777	_{p=0.962 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.042s (± 3.27%)}	_{0.044s (± 9.58%)}	_~	_0.036s	_0.080s	_{p=0.548 n=20}
_{Bind Time}	_{0.014s (± 9.64%)}	_{0.017s (±48.24%)}	_~	_0.011s	_0.090s	_{p=0.895 n=20}
_{Check Time}	_{0.878s (± 0.94%)}	_{0.896s (± 3.14%)}	_~	_0.855s	_1.146s	_{p=0.125 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.963s (± 0.78%)}	_{0.987s (± 4.04%)}	_~	_0.946s	_1.347s	_{p=0.080 n=20}
_{class-transformer - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_45,376	_45,376	_~	_~	_~	_{p=1.000 n=20}
_Types	_7,573	_7,573	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{27,840k (± 0.02%)}	_{27,839k (± 0.02%)}	_~	_27,821k	_27,859k	_{p=0.825 n=20}
_{Memory Allocs}	_{248,121 (± 0.05%)}	_{248,249 (± 0.04%)}	_~	_247,918	_248,738	_{p=0.151 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.012s (± 3.33%)}	_{0.012s (± 3.07%)}	_~	_0.009s	_0.012s	_{p=1.000 n=20}
_{Bind Time}	_{0.004s (±11.02%)}	_{0.003s (± 9.34%)}	_~	_0.003s	_0.005s	_{p=0.880 n=20}
_{Check Time}	_{0.008s (± 4.96%)}	_{0.008s (± 5.86%)}	_~	_0.007s	_0.010s	_{p=0.473 n=20}
_{Emit Time}	_{0.009s (± 4.88%)}	_{0.008s (± 6.59%)}	_~	_0.007s	_0.011s	_{p=0.723 n=20}
_{Total Time}	_{0.032s (± 1.31%)}	_{0.032s (± 1.56%)}	_~	_0.029s	_0.034s	_{p=0.247 n=20}
_{effect - native}
_Errors	₁₂	₁₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,235,115	_1,235,115	_~	_~	_~	_{p=1.000 n=20}
_Types	_894,113	_894,113	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{939,206k (± 0.02%)}	_{939,138k (± 0.02%)}	_~	_938,433k	_940,126k	_{p=0.645 n=20}
_{Memory Allocs}	_{12,633,814 (± 0.01%)}	_{12,634,289 (± 0.02%)}	_~	_12,625,627	_12,650,482	_{p=0.718 n=20}
_{Config Time}	_0.002s	_0.002s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.149s (± 1.88%)}	_{0.150s (± 1.93%)}	_~	_0.140s	_0.163s	_{p=0.498 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.925s (± 1.02%)}	_{0.932s (± 0.86%)}	_~	_0.900s	_0.961s	_{p=0.203 n=20}
_{Emit Time}	_{0.518s (± 1.44%)}	_{0.514s (± 3.00%)}	_~	_0.464s	_0.577s	_{p=0.379 n=20}
_{Total Time}	_{1.690s (± 0.74%)}	_{1.694s (± 0.69%)}	_~	_1.658s	_1.752s	_{p=0.473 n=20}
_{mui-docs - native}
_Errors	_11,405	_11,405	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_3,784,019	_3,784,019	_~	_~	_~	_{p=1.000 n=20}
_Types	_1,355,974	_1,355,974	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{1,767,230k (± 0.06%)}	_{1,768,333k (± 0.06%)}	_~	_1,762,768k	_1,773,323k	_{p=0.102 n=20}
_{Memory Allocs}	_{25,709,935 (± 0.11%)}	_{25,728,714 (± 0.13%)}	_~	_25,652,455	_25,904,180	_{p=0.277 n=20}
_{Config Time}	_0.008s	_0.008s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.290s (± 2.76%)}	_{0.285s (± 1.45%)}	_~	_0.270s	_0.306s	_{p=0.261 n=20}
_{Bind Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{2.935s (± 0.60%)}	_{2.965s (± 0.72%)}	_{+0.029s (+ 1.00%)}	_2.898s	_3.110s	_{p=0.034 n=20}
_{Emit Time}	_{0.240s (± 0.98%)}	_{0.239s (± 2.07%)}	_~	_0.231s	_0.276s	_{p=0.086 n=20}
_{Total Time}	_{3.951s (± 0.45%)}	_{3.990s (± 0.80%)}	_~	_3.911s	_4.166s	_{p=0.062 n=20}
_{sentry - native}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_4,793,245	_4,793,245	_~	_~	_~	_{p=1.000 n=20}
_Types	_2,607,045	_2,607,045	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{2,846,599k (± 0.03%)}	_{2,847,039k (± 0.04%)}	_~	_2,844,208k	_2,852,172k	_{p=0.547 n=20}
_{Memory Allocs}	_{75,023,224 (± 0.21%)}	_{75,005,476 (± 0.16%)}	_~	_74,718,227	_75,572,005	_{p=0.738 n=20}
_{Config Time}	_{0.027s (± 1.61%)}	_{0.026s (± 0.87%)}	_~	_0.026s	_0.027s	_{p=0.216 n=20}
_{Parse Time}	_{0.496s (± 5.52%)}	_{0.479s (± 3.32%)}	_~	_0.438s	_0.557s	_{p=0.473 n=20}
_{Bind Time}	_{0.175s (±11.69%)}	_{0.190s (±10.90%)}	_~	_0.148s	_0.260s	_{p=0.242 n=20}
_{Check Time}	_{7.013s (± 0.53%)}	_{7.031s (± 0.85%)}	_~	_6.814s	_7.351s	_{p=0.733 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{7.762s (± 0.46%)}	_{7.783s (± 0.87%)}	_~	_7.574s	_8.232s	_{p=0.995 n=20}
_{social-app - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,883,074	_1,883,074	_~	_~	_~	_{p=1.000 n=20}
_Types	_1,158,168	_1,158,168	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{966,848k (± 0.02%)}	_{966,966k (± 0.01%)}	_~	_966,535k	_967,491k	_{p=0.473 n=20}
_{Memory Allocs}	_{13,511,699 (± 0.25%)}	_{13,498,876 (± 0.23%)}	_~	_13,440,259	_13,741,357	_{p=0.231 n=20}
_{Config Time}	_{0.008s (± 3.11%)}	_{0.008s (± 2.51%)}	_~	_0.008s	_0.009s	_{p=1.000 n=20}
_{Parse Time}	_{0.163s (± 3.35%)}	_{0.164s (± 4.17%)}	_~	_0.148s	_0.213s	_{p=0.815 n=20}
_{Bind Time}	_{0.048s (± 9.48%)}	_{0.050s (±16.14%)}	_~	_0.040s	_0.112s	_{p=0.952 n=20}
_{Check Time}	_{1.506s (± 2.14%)}	_{1.506s (± 1.82%)}	_~	_1.401s	_1.643s	_{p=0.499 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.744s (± 2.10%)}	_{1.747s (± 1.84%)}	_~	_1.623s	_1.895s	_{p=0.372 n=20}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,184,972	_1,184,972	_~	_~	_~	_{p=1.000 n=20}
_Types	_438,963	_438,963	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{1,175,492k (± 0.40%)}	_{1,172,635k (± 0.29%)}	_~	_1,162,688k	_1,191,743k	_{p=0.277 n=20}
_{Memory Allocs}	_{47,653,691 (± 0.10%)}	_{47,630,013 (± 0.10%)}	_~	_47,437,038	_47,757,688	_{p=0.398 n=20}
_{Config Time}	_{0.002s (±21.99%)}	_{0.002s (±24.84%)}	_~	_0.001s	_0.004s	_{p=0.519 n=20}
_{Parse Time}	_{0.157s (± 5.67%)}	_{0.160s (± 2.42%)}	_{+0.003s (+ 1.85%)}	_0.144s	_0.176s	_{p=0.048 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.923s (± 1.52%)}	_{0.921s (± 1.02%)}	_~	_0.878s	_0.949s	_{p=0.805 n=20}
_{Emit Time}	_{0.165s (± 2.85%)}	_{0.165s (± 2.69%)}	_~	_0.151s	_0.193s	_{p=0.713 n=20}
_{Total Time}	_{10.851s (± 1.61%)}	_{10.834s (± 1.15%)}	_~	_10.163s	_11.266s	_{p=0.878 n=20}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_263,511	_263,511	_~	_~	_~	_{p=1.000 n=20}
_Types	_196,116	_196,116	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{224,129k (± 0.02%)}	_{224,124k (± 0.02%)}	_~	_223,938k	_224,366k	_{p=0.763 n=20}
_{Memory Allocs}	_{2,389,340 (± 0.02%)}	_{2,389,390 (± 0.02%)}	_~	_2,387,733	_2,391,040	_{p=0.968 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.049s (± 3.01%)}	_{0.049s (± 3.72%)}	_~	_0.044s	_0.055s	_{p=0.376 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.380s (± 0.65%)}	_{0.385s (± 0.99%)}	_{+0.005s (+ 1.39%)}	_0.372s	_0.404s	_{p=0.032 n=20}
_{Emit Time}	_{0.048s (± 5.24%)}	_{0.050s (± 5.35%)}	_~	_0.042s	_0.058s	_{p=0.321 n=20}
_{Total Time}	_{0.506s (± 0.72%)}	_{0.513s (± 0.79%)}	_{+0.007s (+ 1.32%)}	_0.498s	_0.532s	_{p=0.007 n=20}
_{t3code-server - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_4,350,661	_4,350,661	_~	_~	_~	_{p=1.000 n=20}
_Types	_3,040,644	_3,040,644	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{2,425,440k (± 0.02%)}	_{2,425,459k (± 0.03%)}	_~	_2,423,749k	_2,428,134k	_{p=0.512 n=20}
_{Memory Allocs}	_{37,201,180 (± 0.14%)}	_{37,174,680 (± 0.08%)}	_~	_37,094,565	_37,362,933	_{p=0.583 n=20}
_{Config Time}	_0.003s	_0.003s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.257s (± 1.68%)}	_{0.251s (± 2.32%)}	_~	_0.223s	_0.268s	_{p=0.245 n=20}
_{Bind Time}	_{0.081s (± 4.66%)}	_{0.094s (±12.62%)}	_~	_0.074s	_0.143s	_{p=0.446 n=20}
_{Check Time}	_{6.771s (± 0.94%)}	_{6.788s (± 1.15%)}	_~	_6.654s	_7.434s	_{p=0.794 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{7.122s (± 0.92%)}	_{7.146s (± 1.08%)}	_~	_7.013s	_7.784s	_{p=0.625 n=20}
_{tanstack-router - native}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_571,756	_571,756	_~	_~	_~	_{p=1.000 n=20}
_Types	_397,689	_397,689	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{326,066k (± 0.01%)}	_{326,068k (± 0.02%)}	_~	_325,775k	_326,251k	_{p=0.718 n=20}
_{Memory Allocs}	_{4,333,598 (± 0.17%)}	_{4,335,145 (± 0.21%)}	_~	_4,321,395	_4,400,445	_{p=0.947 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.040s (± 3.72%)}	_{0.039s (± 3.91%)}	_~	_0.034s	_0.045s	_{p=0.888 n=20}
_{Bind Time}	_{0.013s (± 9.22%)}	_{0.014s (±12.65%)}	_~	_0.011s	_0.021s	_{p=0.735 n=20}
_{Check Time}	_{0.499s (± 0.58%)}	_{0.504s (± 0.68%)}	_~	_0.495s	_0.524s	_{p=0.109 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.571s (± 0.65%)}	_{0.576s (± 0.70%)}	_~	_0.563s	_0.597s	_{p=0.174 n=20}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_231,616	_231,616	_~	_~	_~	_{p=1.000 n=20}
_Types	_181,195	_181,195	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{193,191k (± 0.01%)}	_{193,216k (± 0.02%)}	_~	_193,098k	_193,371k	_{p=0.324 n=20}
_{Memory Allocs}	_{1,310,302 (± 0.01%)}	_{1,310,568 (± 0.01%)}	_{+265 (+ 0.02%)}	_1,310,025	_1,311,387	_{p=0.010 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.043s (± 3.16%)}	_{0.044s (± 2.60%)}	_~	_0.040s	_0.050s	_{p=0.437 n=20}
_{Bind Time}	_{0.021s (± 5.70%)}	_{0.020s (± 4.96%)}	_~	_0.016s	_0.024s	_{p=0.339 n=20}
_{Check Time}	_{0.288s (± 0.85%)}	_{0.295s (± 0.98%)}	_{+0.007s (+ 2.36%)}	_0.284s	_0.303s	_{p=0.000 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.358s (± 0.65%)}	_{0.365s (± 0.65%)}	_{+0.007s (+ 1.94%)}	_0.357s	_0.373s	_{p=0.000 n=20}
_{vscode - native}
_Errors	₁₁	₁₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_7,538,620	_7,538,620	_~	_~	_~	_{p=1.000 n=20}
_Types	_4,426,130	_4,426,130	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{5,221,483k (± 0.01%)}	_{5,222,238k (± 0.02%)}	_~	_5,218,769k	_5,227,694k	_{p=0.149 n=20}
_{Memory Allocs}	_{57,160,636 (± 0.02%)}	_{57,156,601 (± 0.02%)}	_~	_57,135,338	_57,199,600	_{p=0.862 n=20}
_{Config Time}	_{0.037s (± 0.76%)}	_{0.037s (± 0.73%)}	_~	_0.036s	_0.038s	_{p=0.665 n=20}
_{Parse Time}	_{0.909s (± 2.35%)}	_{0.909s (± 2.16%)}	_~	_0.830s	_0.975s	_{p=0.597 n=20}
_{Bind Time}	_{0.315s (± 7.56%)}	_{0.322s (± 7.45%)}	_~	_0.290s	_0.487s	_{p=0.995 n=20}
_{Check Time}	_{7.570s (± 0.77%)}	_{7.564s (± 0.79%)}	_~	_7.375s	_7.836s	_{p=0.826 n=20}
_{Emit Time}	_{2.817s (± 5.45%)}	_{2.918s (± 5.98%)}	_~	_2.623s	_3.630s	_{p=0.204 n=20}
_{Total Time}	_{11.708s (± 1.12%)}	_{11.811s (± 1.23%)}	_~	_11.519s	_12.500s	_{p=0.172 n=20}
_{webpack - native}
_Errors	₆₁₂	₆₁₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_925,725	_925,725	_~	_~	_~	_{p=1.000 n=20}
_Types	_650,047	_650,047	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{697,592k (± 0.02%)}	_{697,665k (± 0.02%)}	_~	_697,099k	_698,152k	_{p=0.327 n=20}
_{Memory Allocs}	_{6,505,539 (± 0.04%)}	_{6,504,689 (± 0.04%)}	_~	_6,498,283	_6,521,003	_{p=0.529 n=20}
_{Config Time}	_0.004s	_0.004s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.148s (± 5.54%)}	_{0.145s (± 2.97%)}	_~	_0.129s	_0.163s	_{p=0.683 n=20}
_{Bind Time}	_{0.051s (±12.32%)}	_{0.049s (±12.38%)}	_~	_0.038s	_0.077s	_{p=0.541 n=20}
_{Check Time}	_{1.014s (± 0.78%)}	_{1.034s (± 0.80%)}	_{+0.020s (+ 1.93%)}	_1.001s	_1.074s	_{p=0.002 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.241s (± 1.14%)}	_{1.259s (± 1.01%)}	_{+0.018s (+ 1.42%)}	_1.206s	_1.311s	_{p=0.032 n=20}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_640,490	_640,490	_~	_~	_~	_{p=1.000 n=20}
_Types	_387,984	_387,984	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{349,520k (± 0.02%)}	_{349,465k (± 0.02%)}	_~	_349,178k	_349,777k	_{p=0.183 n=20}
_{Memory Allocs}	_{3,969,049 (± 0.10%)}	_{3,967,887 (± 0.06%)}	_~	_3,955,869	_3,977,672	_{p=0.841 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.069s (± 2.72%)}	_{0.069s (± 2.34%)}	_~	_0.061s	_0.074s	_{p=0.888 n=20}
_{Bind Time}	_{0.025s (±11.37%)}	_{0.025s (±10.33%)}	_~	_0.019s	_0.037s	_{p=0.898 n=20}
_{Check Time}	_{0.444s (± 1.74%)}	_{0.446s (± 1.88%)}	_~	_0.409s	_0.485s	_{p=0.588 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.545s (± 1.78%)}	_{0.546s (± 1.70%)}	_~	_0.499s	_0.585s	_{p=0.499 n=20}

System info unknown

Hosts

native

Scenarios

Compiler-Unions - native
angular-1 - native
arktype - native
class-transformer - native
effect - native
mui-docs - native
sentry - native
social-app - native
strada-build-src - native
strada-compiler - native
t3code-server - native
tanstack-router - native
ts-pre-modules - native
vscode - native
webpack - native
xstate-main - native

_Benchmark	_Name	_Iterations
_Current	_pr	₂₀
_Baseline	_baseline	₂₀

Developer Information:

Download Benchmarks

typescript-automation · 2026-10-30T17:35:31Z

Anders Hejlsberg (@ahejlsberg) Here are the results of running the top 400 repos with tsc comparing baseline and pr:

Everything looks good!

Jake Bailey (jakebailey) · 2026-10-30T18:51:00Z

Interestingly, though perhaps not surprisingly, my branch that is making the checker order-independent / idempotent does actually also fix this problem, it seems.

I'll have to finally open that PR and expose everyone to the horrorshow.

Anders Hejlsberg (ahejlsberg) · 2026-10-30T19:14:32Z

Interestingly, though perhaps not surprisingly, my branch that is making the checker order-independent / idempotent does actually also fix this problem, it seems.

I'm curious to see how.

Jake Bailey (jakebailey) · 2026-10-30T19:30:30Z

Basically, during resolution, it installs a temporarily layout of just the declared members. It doesn't search the base types during resolution, though.

~~Interestingly, for sharedMemberLayoutThisIntersectionBase, my big branch does not error on the A & B case since m does exist?~~ No, my behavior matches.

I'm currently rebasing it and will send it just so people can play with it.

Jake Bailey (jakebailey) · 2026-10-30T20:54:52Z

I sent #65064 just to at least have something out there to point at.

Jake Bailey (jakebailey) · 2026-10-30T21:42:03Z

I was wrong before; I think my branch's behavior matches. But I think that this PR is technically order dependent? Hard to come up with an example though, but I can see isStringIndexSignatureOnlyType returning false for something in progress even if it would answer true later?

Anders Hejlsberg (ahejlsberg) · 2026-10-30T23:13:52Z

I was wrong before; I think my branch's behavior matches.

Matches what?

Jake Bailey (jakebailey) · 2026-10-30T23:16:34Z

This PR's, since I had already "fixed" this unknowingly.

Anders Hejlsberg (ahejlsberg) · 2026-10-30T23:30:41Z

Hmm, yeah, #65064 has some pretty complex and scary looking code guarded by a new ObjectFlagsMembersResolving flag. Plus it first installs one member layout with no base classes and then later replaces it with the full layout. No sure how it gets away with that without inconsistencies.

Anders Hejlsberg (ahejlsberg) · 2026-10-30T23:40:09Z

But I think that this PR is technically order dependent?

Possibly. But I just added a change that excludes class/interface types from isStringIndexSignatureOnlyType. That function was added years ago in #30769 to simplify things like { [key: string]: XXX }[K] into just XXX, but wasn't really concerned with classes or interfaces on the object side of the indexed access.

Anders Hejlsberg (ahejlsberg) · 2026-10-30T23:40:30Z

TypeScript Bot (@typescript-bot) test it

typescript-automation · 2026-10-30T23:40:35Z

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-automation · 2026-10-31T00:13:39Z

Hey Anders Hejlsberg (@ahejlsberg), the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

typescript-automation · 2026-10-31T00:22:47Z

Anders Hejlsberg (@ahejlsberg) Here are the results of running the user tests with tsc comparing baseline and pr:

Everything looks good!

typescript-automation · 2026-10-31T00:30:38Z

Anders Hejlsberg (@ahejlsberg)
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 - native}
_Errors	₄₁	₄₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_88,466	_88,466	_~	_~	_~	_{p=1.000 n=20}
_Types	_79,607	_79,607	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{107,497k (± 0.03%)}	_{107,471k (± 0.03%)}	_~	_107,355k	_107,569k	_{p=0.273 n=20}
_{Memory Allocs}	_{1,262,214 (± 0.01%)}	_{1,262,166 (± 0.01%)}	_~	_1,261,814	_1,262,668	_{p=0.341 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.023s (± 2.46%)}	_{0.024s (± 2.92%)}	_~	_0.020s	_0.027s	_{p=0.280 n=20}
_{Bind Time}	_{0.008s (± 5.95%)}	_{0.008s (± 4.81%)}	_~	_0.007s	_0.010s	_{p=0.781 n=20}
_{Check Time}	_{0.214s (± 0.85%)}	_{0.217s (± 0.70%)}	_{+0.003s (+ 1.50%)}	_0.211s	_0.223s	_{p=0.005 n=20}
_{Emit Time}	_{0.136s (± 0.82%)}	_{0.136s (± 0.93%)}	_~	_0.132s	_0.143s	_{p=0.574 n=20}
_{Total Time}	_{0.384s (± 0.56%)}	_{0.388s (± 0.46%)}	_{+0.004s (+ 0.91%)}	_0.382s	_0.395s	_{p=0.011 n=20}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_586,553	_586,553	_~	_~	_~	_{p=1.000 n=20}
_Types	_241,682	_241,682	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{519,769k (± 0.02%)}	_{519,712k (± 0.02%)}	_~	_519,427k	_520,176k	_{p=0.449 n=20}
_{Memory Allocs}	_{7,794,126 (± 0.10%)}	_{7,788,999 (± 0.10%)}	_~	_7,779,236	_7,836,009	_{p=0.165 n=20}
_{Config Time}	_0.009s	_0.009s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.119s (± 2.03%)}	_{0.124s (± 2.85%)}	_{🔻+0.005s (+ 4.27%)}	_0.114s	_0.144s	_{p=0.033 n=20}
_{Bind Time}	_{0.047s (±10.13%)}	_{0.041s (± 9.07%)}	_{🟩-0.006s (-12.61%)}	_0.035s	_0.061s	_{p=0.014 n=20}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=20}
_{Emit Time}	_{0.632s (± 0.76%)}	_{0.628s (± 0.73%)}	_~	_0.616s	_0.656s	_{p=0.115 n=20}
_{Total Time}	_{0.819s (± 0.40%)}	_{0.814s (± 0.87%)}	_~	_0.791s	_0.855s	_{p=0.139 n=20}
_{arktype - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_685,920	_685,920	_~	_~	_~	_{p=1.000 n=20}
_Types	_939,467	_939,447	_{-20 (- 0.00%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{495,313k (± 0.01%)}	_{495,013k (± 0.01%)}	_{-300k (- 0.06%)}	_494,847k	_495,293k	_{p=0.000 n=20}
_{Memory Allocs}	_{12,062,105 (± 0.02%)}	_{12,059,515 (± 0.01%)}	_{-2,591 (- 0.02%)}	_12,056,786	_12,064,828	_{p=0.023 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.042s (± 3.52%)}	_{0.042s (± 3.61%)}	_~	_0.037s	_0.049s	_{p=0.941 n=20}
_{Bind Time}	_{0.013s (± 8.99%)}	_{0.013s (± 9.13%)}	_~	_0.011s	_0.019s	_{p=0.974 n=20}
_{Check Time}	_{0.871s (± 0.51%)}	_{0.876s (± 0.64%)}	_~	_0.859s	_0.903s	_{p=0.203 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.953s (± 0.41%)}	_{0.959s (± 0.54%)}	_~	_0.942s	_0.980s	_{p=0.095 n=20}
_{class-transformer - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_45,376	_45,376	_~	_~	_~	_{p=1.000 n=20}
_Types	_7,573	_7,573	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{27,891k (± 0.03%)}	_{27,887k (± 0.03%)}	_~	_27,852k	_27,912k	_{p=0.323 n=20}
_{Memory Allocs}	_{248,229 (± 0.06%)}	_{248,311 (± 0.06%)}	_~	_247,880	_249,077	_{p=0.457 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.012s (± 3.33%)}	_{0.011s (± 3.06%)}	_~	_0.009s	_0.012s	_{p=0.352 n=20}
_{Bind Time}	_{0.003s (±11.19%)}	_{0.003s (±12.11%)}	_~	_0.002s	_0.005s	_{p=0.434 n=20}
_{Check Time}	_{0.008s (± 5.14%)}	_{0.008s (± 6.79%)}	_~	_0.006s	_0.009s	_{p=0.839 n=20}
_{Emit Time}	_{0.007s (± 7.27%)}	_{0.008s (± 7.89%)}	_~	_0.006s	_0.010s	_{p=0.207 n=20}
_{Total Time}	_{0.030s (± 2.00%)}	_{0.031s (± 2.53%)}	_~	_0.026s	_0.034s	_{p=0.502 n=20}
_{effect - native}
_Errors	₁₂	₁₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,235,115	_1,235,115	_~	_~	_~	_{p=1.000 n=20}
_Types	_894,113	_892,870	_{-1,243 (- 0.14%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{949,974k (± 0.02%)}	_{948,549k (± 0.03%)}	_{-1,425k (- 0.15%)}	_947,711k	_949,617k	_{p=0.000 n=20}
_{Memory Allocs}	_{12,640,617 (± 0.05%)}	_{12,636,894 (± 0.07%)}	_~	_12,620,609	_12,692,302	_{p=0.060 n=20}
_{Config Time}	_{0.002s (± 9.93%)}	_0.002s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.154s (± 6.89%)}	_{0.147s (± 1.47%)}	_~	_0.139s	_0.159s	_{p=0.393 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.918s (± 8.97%)}	_{0.899s (± 1.21%)}	_{-0.019s (- 2.07%)}	_0.866s	_0.953s	_{p=0.010 n=20}
_{Emit Time}	_{0.495s (± 1.46%)}	_{0.499s (± 3.70%)}	_~	_0.465s	_0.652s	_{p=0.587 n=20}
_{Total Time}	_{1.667s (± 5.27%)}	_{1.641s (± 1.46%)}	_~	_1.590s	_1.817s	_{p=0.143 n=20}
_{mui-docs - native}
_Errors	_11,405	_11,405	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_3,784,019	_3,784,019	_~	_~	_~	_{p=1.000 n=20}
_Types	_1,355,974	_1,355,974	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{1,767,679k (± 0.08%)}	_{1,769,280k (± 0.05%)}	_~	_1,764,032k	_1,771,978k	_{p=0.121 n=20}
_{Memory Allocs}	_{25,742,822 (± 0.17%)}	_{25,740,744 (± 0.10%)}	_~	_25,656,150	_25,860,371	_{p=0.512 n=20}
_{Config Time}	_{0.008s (± 1.77%)}	_{0.008s (± 1.77%)}	_~	_0.008s	_0.009s	_{p=1.000 n=20}
_{Parse Time}	_{0.282s (± 1.78%)}	_{0.285s (± 2.92%)}	_~	_0.245s	_0.336s	_{p=0.713 n=20}
_{Bind Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{2.967s (± 0.88%)}	_{3.000s (± 1.50%)}	_~	_2.911s	_3.345s	_{p=0.337 n=20}
_{Emit Time}	_{0.242s (± 1.29%)}	_{0.243s (± 1.12%)}	_~	_0.234s	_0.256s	_{p=0.541 n=20}
_{Total Time}	_{3.986s (± 0.72%)}	_{4.033s (± 1.18%)}	_~	_3.922s	_4.370s	_{p=0.176 n=20}
_{sentry - native}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_4,793,245	_4,793,245	_~	_~	_~	_{p=1.000 n=20}
_Types	_2,606,905	_2,606,848	_{-57 (- 0.00%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{2,846,171k (± 0.04%)}	_{2,844,533k (± 0.03%)}	_{-1,637k (- 0.06%)}	_2,841,865k	_2,849,689k	_{p=0.021 n=20}
_{Memory Allocs}	_{74,932,361 (± 0.17%)}	_{75,170,249 (± 0.37%)}	_~	_74,560,866	_76,587,654	_{p=0.165 n=20}
_{Config Time}	_{0.025s (± 1.35%)}	_{0.025s (± 1.28%)}	_~	_0.024s	_0.026s	_{p=0.944 n=20}
_{Parse Time}	_{0.471s (± 5.78%)}	_{0.487s (± 4.87%)}	_~	_0.425s	_0.618s	_{p=0.104 n=20}
_{Bind Time}	_{0.162s (± 9.42%)}	_{0.160s (±10.92%)}	_~	_0.126s	_0.242s	_{p=0.440 n=20}
_{Check Time}	_{6.633s (± 0.94%)}	_{6.655s (± 0.66%)}	_~	_6.528s	_6.939s	_{p=0.365 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{7.351s (± 0.86%)}	_{7.383s (± 0.66%)}	_~	_7.176s	_7.646s	_{p=0.110 n=20}
_{social-app - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,883,074	_1,883,074	_~	_~	_~	_{p=1.000 n=20}
_Types	_1,158,168	_1,158,094	_{-74 (- 0.01%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{966,994k (± 0.01%)}	_{966,627k (± 0.02%)}	_{-367k (- 0.04%)}	_965,794k	_967,167k	_{p=0.000 n=20}
_{Memory Allocs}	_{13,500,189 (± 0.13%)}	_{13,489,353 (± 0.10%)}	_~	_13,441,150	_13,570,333	_{p=0.414 n=20}
_{Config Time}	_0.008s	_0.008s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.163s (± 3.87%)}	_{0.164s (± 1.77%)}	_~	_0.154s	_0.180s	_{p=0.143 n=20}
_{Bind Time}	_{0.041s (± 7.21%)}	_{0.042s (± 8.10%)}	_~	_0.035s	_0.065s	_{p=0.941 n=20}
_{Check Time}	_{1.435s (± 1.02%)}	_{1.446s (± 0.83%)}	_~	_1.408s	_1.500s	_{p=0.208 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.665s (± 1.05%)}	_{1.678s (± 0.64%)}	_~	_1.654s	_1.729s	_{p=0.122 n=20}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,184,972	_1,184,972	_~	_~	_~	_{p=1.000 n=20}
_Types	_438,959	_438,959	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{1,171,248k (± 0.34%)}	_{1,171,773k (± 0.38%)}	_~	_1,156,264k	_1,188,785k	_{p=0.862 n=20}
_{Memory Allocs}	_{47,570,938 (± 0.09%)}	_{47,564,133 (± 0.09%)}	_~	_47,398,135	_47,779,828	_{p=0.583 n=20}
_{Config Time}	_{0.002s (±14.66%)}	_{0.002s (±13.76%)}	_~	_0.001s	_0.003s	_{p=0.165 n=20}
_{Parse Time}	_{0.139s (± 1.82%)}	_{0.138s (± 2.09%)}	_~	_0.127s	_0.153s	_{p=0.683 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.810s (± 0.52%)}	_{0.810s (± 0.59%)}	_~	_0.796s	_0.833s	_{p=0.703 n=20}
_{Emit Time}	_{0.141s (± 2.07%)}	_{0.140s (± 1.57%)}	_~	_0.135s	_0.155s	_{p=0.470 n=20}
_{Total Time}	_{9.414s (± 0.75%)}	_{9.407s (± 0.73%)}	_~	_9.129s	_9.737s	_{p=0.820 n=20}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_263,511	_263,511	_~	_~	_~	_{p=1.000 n=20}
_Types	_196,116	_196,116	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{223,530k (± 0.01%)}	_{223,537k (± 0.02%)}	_~	_223,265k	_223,770k	_{p=0.606 n=20}
_{Memory Allocs}	_{2,389,515 (± 0.01%)}	_{2,389,490 (± 0.02%)}	_~	_2,387,547	_2,390,873	_{p=0.925 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.049s (± 2.93%)}	_{0.049s (± 3.91%)}	_~	_0.042s	_0.057s	_{p=0.867 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.373s (± 1.30%)}	_{0.373s (± 0.72%)}	_~	_0.363s	_0.385s	_{p=0.596 n=20}
_{Emit Time}	_{0.046s (± 5.04%)}	_{0.047s (± 5.29%)}	_~	_0.042s	_0.061s	_{p=0.604 n=20}
_{Total Time}	_{0.494s (± 1.04%)}	_{0.495s (± 0.97%)}	_~	_0.480s	_0.523s	_{p=0.763 n=20}
_{t3code-server - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_4,350,661	_4,350,661	_~	_~	_~	_{p=1.000 n=20}
_Types	_3,040,644	_3,040,530	_{-114 (- 0.00%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{2,417,290k (± 0.02%)}	_{2,415,633k (± 0.02%)}	_{-1,657k (- 0.07%)}	_2,414,501k	_2,419,333k	_{p=0.000 n=20}
_{Memory Allocs}	_{37,188,430 (± 0.07%)}	_{37,171,564 (± 0.08%)}	_~	_37,104,496	_37,347,175	_{p=0.192 n=20}
_{Config Time}	_0.003s	_0.003s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.260s (± 2.95%)}	_{0.257s (± 2.49%)}	_~	_0.234s	_0.290s	_{p=0.569 n=20}
_{Bind Time}	_{0.104s (±10.70%)}	_{0.093s (± 8.19%)}	_~	_0.078s	_0.138s	_{p=0.122 n=20}
_{Check Time}	_{6.252s (± 1.27%)}	_{6.332s (± 1.23%)}	_~	_5.874s	_6.600s	_{p=0.098 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{6.632s (± 1.25%)}	_{6.697s (± 1.24%)}	_~	_6.224s	_6.984s	_{p=0.245 n=20}
_{tanstack-router - native}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_571,756	_571,756	_~	_~	_~	_{p=1.000 n=20}
_Types	_397,689	_397,447	_{-242 (- 0.06%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{326,501k (± 0.02%)}	_{326,338k (± 0.01%)}	_{-163k (- 0.05%)}	_326,180k	_326,517k	_{p=0.000 n=20}
_{Memory Allocs}	_{4,329,324 (± 0.12%)}	_{4,332,647 (± 0.14%)}	_~	_4,319,363	_4,358,048	_{p=0.640 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.040s (± 3.20%)}	_{0.039s (± 3.40%)}	_~	_0.035s	_0.045s	_{p=0.680 n=20}
_{Bind Time}	_{0.013s (±13.13%)}	_{0.013s (±11.12%)}	_~	_0.010s	_0.019s	_{p=0.502 n=20}
_{Check Time}	_{0.494s (± 0.52%)}	_{0.501s (± 0.41%)}	_{+0.007s (+ 1.42%)}	_0.492s	_0.509s	_{p=0.000 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.564s (± 0.63%)}	_{0.572s (± 0.58%)}	_{+0.008s (+ 1.36%)}	_0.559s	_0.582s	_{p=0.001 n=20}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_231,616	_231,616	_~	_~	_~	_{p=1.000 n=20}
_Types	_181,195	_181,195	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{192,971k (± 0.02%)}	_{192,958k (± 0.02%)}	_~	_192,807k	_193,127k	_{p=0.588 n=20}
_{Memory Allocs}	_{1,310,131 (± 0.02%)}	_{1,310,358 (± 0.03%)}	_~	_1,309,007	_1,311,615	_{p=0.331 n=20}
_{Config Time}	_{0.000s (±208.60%)}	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.044s (± 3.40%)}	_{0.045s (± 3.60%)}	_~	_0.038s	_0.051s	_{p=0.909 n=20}
_{Bind Time}	_{0.020s (± 5.63%)}	_{0.021s (± 4.99%)}	_~	_0.017s	_0.024s	_{p=0.292 n=20}
_{Check Time}	_{0.304s (± 1.43%)}	_{0.311s (± 1.83%)}	_~	_0.294s	_0.350s	_{p=0.109 n=20}
_{Emit Time}	_{0.000s (±208.60%)}	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.376s (± 1.39%)}	_{0.383s (± 1.44%)}	_{+0.007s (+ 1.90%)}	_0.369s	_0.422s	_{p=0.043 n=20}
_{vscode - native}
_Errors	₁₁	₁₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_7,553,577	_7,553,577	_~	_~	_~	_{p=1.000 n=20}
_Types	_4,415,359	_4,415,297	_{-62 (- 0.00%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{5,226,573k (± 0.02%)}	_{5,223,066k (± 0.01%)}	_{-3,507k (- 0.07%)}	_5,220,487k	_5,225,155k	_{p=0.000 n=20}
_{Memory Allocs}	_{57,131,365 (± 0.06%)}	_{57,108,922 (± 0.02%)}	_{-22,443 (- 0.04%)}	_57,082,738	_57,171,551	_{p=0.035 n=20}
_{Config Time}	_{0.034s (± 1.63%)}	_{0.034s (± 2.61%)}	_~	_0.033s	_0.041s	_{p=0.528 n=20}
_{Parse Time}	_{0.902s (± 2.12%)}	_{0.891s (± 2.93%)}	_~	_0.794s	_1.069s	_{p=0.194 n=20}
_{Bind Time}	_{0.315s (± 5.75%)}	_{0.328s (± 8.50%)}	_~	_0.288s	_0.508s	_{p=0.784 n=20}
_{Check Time}	_{7.117s (± 2.10%)}	_{7.137s (± 2.47%)}	_~	_6.809s	_8.423s	_{p=0.820 n=20}
_{Emit Time}	_{1.992s (± 5.04%)}	_{2.158s (± 7.23%)}	_~	_1.874s	_2.864s	_{p=0.147 n=20}
_{Total Time}	_{10.419s (± 1.94%)}	_{10.609s (± 2.15%)}	_~	_10.126s	_11.998s	_{p=0.066 n=20}
_{webpack - native}
_Errors	₆₁₂	₆₁₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_925,190	_925,190	_~	_~	_~	_{p=1.000 n=20}
_Types	_643,199	_643,183	_{-16 (- 0.00%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{697,712k (± 0.01%)}	_{697,586k (± 0.01%)}	_~	_697,264k	_697,927k	_{p=0.068 n=20}
_{Memory Allocs}	_{6,474,059 (± 0.06%)}	_{6,473,348 (± 0.05%)}	_~	_6,465,065	_6,491,536	_{p=0.698 n=20}
_{Config Time}	_0.004s	_0.004s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.145s (± 3.56%)}	_{0.139s (± 2.28%)}	_~	_0.124s	_0.152s	_{p=0.056 n=20}
_{Bind Time}	_{0.043s (± 5.06%)}	_{0.045s (± 9.03%)}	_~	_0.038s	_0.067s	_{p=0.887 n=20}
_{Check Time}	_{0.994s (± 0.68%)}	_{0.998s (± 0.61%)}	_~	_0.977s	_1.022s	_{p=0.234 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.210s (± 0.74%)}	_{1.210s (± 0.69%)}	_~	_1.179s	_1.247s	_{p=0.683 n=20}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_640,490	_640,490	_~	_~	_~	_{p=1.000 n=20}
_Types	_387,984	_387,708	_{-276 (- 0.07%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{350,103k (± 0.03%)}	_{349,835k (± 0.02%)}	_{-268k (- 0.08%)}	_349,569k	_350,199k	_{p=0.000 n=20}
_{Memory Allocs}	_{3,969,038 (± 0.09%)}	_{3,966,236 (± 0.07%)}	_~	_3,959,505	_3,983,840	_{p=0.369 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.060s (± 2.92%)}	_{0.060s (± 2.84%)}	_~	_0.054s	_0.067s	_{p=0.682 n=20}
_{Bind Time}	_{0.020s (±11.21%)}	_{0.023s (±13.69%)}	_~	_0.017s	_0.035s	_{p=0.313 n=20}
_{Check Time}	_{0.397s (± 1.10%)}	_{0.399s (± 1.14%)}	_~	_0.385s	_0.423s	_{p=0.464 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.485s (± 1.12%)}	_{0.488s (± 1.19%)}	_~	_0.470s	_0.516s	_{p=0.379 n=20}

System info unknown

Hosts

native

Scenarios

Compiler-Unions - native
angular-1 - native
arktype - native
class-transformer - native
effect - native
mui-docs - native
sentry - native
social-app - native
strada-build-src - native
strada-compiler - native
t3code-server - native
tanstack-router - native
ts-pre-modules - native
vscode - native
webpack - native
xstate-main - native

_Benchmark	_Name	_Iterations
_Current	_pr	₂₀
_Baseline	_baseline	₂₀

Developer Information:

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typescript-automation · 2026-10-31T01:17:43Z

Anders Hejlsberg (@ahejlsberg) Here are the results of running the top 400 repos with tsc comparing baseline and pr:

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Anders Hejlsberg (ahejlsberg) added 3 commits October 30, 2026 08:27

Allow accessing named declared members during a type's resolution

2d6a750

Accept new baselines

0a5b278

Add regression tests

d59ed3f

Copilot AI balanced review requested due to automatic review settings October 30, 2026 15:53

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Anders Hejlsberg (ahejlsberg) requested review from Daniel Rosenwasser (DanielRosenwasser), Ryan Cavanaugh (RyanCavanaugh), Gabriela Araujo Britto (gabritto) and Jake Bailey (jakebailey) October 30, 2026 15:54

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Don't compute address of array element that might move

f597365

Daniel Rosenwasser (DanielRosenwasser) approved these changes Oct 30, 2026

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github-project-automation Bot moved this from Not started to Needs merge in PR Backlog Oct 30, 2026

Anders Hejlsberg (ahejlsberg) added 2 commits October 30, 2026 16:35

Exclude class/interface types from isStringIndexSignatureOnlyType

96bc57f

Accept new baselines

7000c3c

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