[experiment] Avoid resolving property types that cannot be unit types when looking for key properties - #65056

Mateusz Burzyński (Andarist) · 2026-10-30T15:12:17Z

No description provided.

… for key properties

Jake Bailey (jakebailey) · 2026-10-30T15:13:28Z

TypeScript Bot (@typescript-bot) test it

typescript-automation · 2026-10-30T15:13:34Z

Hey Jake Bailey (@jakebailey), this PR was updated less than two minutes before this command. Please wait until it has been unchanged for two minutes and try again.

Jake Bailey (jakebailey) · 2026-10-30T15:20:17Z

TypeScript Bot (@typescript-bot) test it

typescript-automation · 2026-10-30T15:20:23Z

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 · 2026-10-30T15:54:14Z

Hey Jake Bailey (@jakebailey), the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

typescript-automation · 2026-10-30T16:01:40Z

Jake Bailey (@jakebailey) Here are the results of running the user tests with tsc comparing baseline and pr:

Everything looks good!

typescript-automation · 2026-10-30T16:16:54Z

Jake Bailey (@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 - native}
_Errors	₄₁	₄₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_88,466	_88,466	_~	_~	_~	_{p=1.000 n=20}
_Types	_79,607	_77,569	_{-2,038 (- 2.56%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{104,071k (± 0.02%)}	_{103,650k (± 0.03%)}	_{-420k (- 0.40%)}	_103,559k	_103,744k	_{p=0.000 n=20}
_{Memory Allocs}	_{1,262,379 (± 0.01%)}	_{1,257,565 (± 0.01%)}	_{-4,814 (- 0.38%)}	_1,256,980	_1,258,149	_{p=0.000 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.023s (± 3.59%)}	_{0.023s (± 3.63%)}	_~	_0.019s	_0.025s	_{p=0.886 n=20}
_{Bind Time}	_{0.009s (± 5.40%)}	_{0.009s (± 6.89%)}	_~	_0.007s	_0.011s	_{p=0.887 n=20}
_{Check Time}	_{0.209s (± 0.66%)}	_{0.211s (± 0.72%)}	_~	_0.206s	_0.219s	_{p=0.087 n=20}
_{Emit Time}	_{0.136s (± 0.80%)}	_{0.137s (± 0.69%)}	_~	_0.134s	_0.141s	_{p=0.629 n=20}
_{Total Time}	_{0.379s (± 0.34%)}	_{0.382s (± 0.48%)}	_~	_0.376s	_0.391s	_{p=0.054 n=20}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_{586,489 (± 0.02%)}	_{586,498 (± 0.02%)}	_~	_586,063	_586,825	_{p=0.794 n=20}
_Types	_{241,688 (± 0.00%)}	_{234,199 (± 0.00%)}	_{🟩-7,489 (- 3.10%)}	_234,196	_234,212	_{p=0.000 n=20}
_{Memory Used}	_{517,715k (± 0.01%)}	_{516,212k (± 0.02%)}	_{-1,503k (- 0.29%)}	_515,880k	_516,814k	_{p=0.000 n=20}
_{Memory Allocs}	_{7,793,407 (± 0.10%)}	_{7,776,389 (± 0.13%)}	_{-17,017 (- 0.22%)}	_7,762,915	_7,848,317	_{p=0.000 n=20}
_{Config Time}	_{0.008s (± 2.73%)}	_{0.008s (± 2.10%)}	_~	_0.008s	_0.009s	_{p=0.273 n=20}
_{Parse Time}	_{0.132s (± 7.18%)}	_{0.122s (± 2.69%)}	_~	_0.112s	_0.144s	_{p=0.135 n=20}
_{Bind Time}	_{0.043s (± 7.30%)}	_{0.047s (±11.90%)}	_~	_0.038s	_0.075s	_{p=0.516 n=20}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=20}
_{Emit Time}	_{0.845s (± 0.94%)}	_{0.854s (± 1.00%)}	_~	_0.827s	_0.884s	_{p=0.103 n=20}
_{Total Time}	_{1.040s (± 1.32%)}	_{1.043s (± 1.24%)}	_~	_1.010s	_1.090s	_{p=0.525 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	_934,240	_{-5,227 (- 0.56%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{494,721k (± 0.01%)}	_{493,596k (± 0.01%)}	_{-1,125k (- 0.23%)}	_493,364k	_493,804k	_{p=0.000 n=20}
_{Memory Allocs}	_{12,062,902 (± 0.01%)}	_{12,051,296 (± 0.02%)}	_{-11,606 (- 0.10%)}	_12,047,042	_12,063,113	_{p=0.000 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.041s (± 3.89%)}	_{0.040s (± 2.43%)}	_~	_0.036s	_0.044s	_{p=0.660 n=20}
_{Bind Time}	_{0.014s (± 9.73%)}	_{0.013s (± 9.31%)}	_~	_0.011s	_0.019s	_{p=0.347 n=20}
_{Check Time}	_{0.958s (± 0.65%)}	_{0.962s (± 0.67%)}	_~	_0.934s	_0.981s	_{p=0.372 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.043s (± 0.53%)}	_{1.045s (± 0.52%)}	_~	_1.021s	_1.064s	_{p=0.606 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	_7,366	_{-207 (- 2.73%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{27,838k (± 0.02%)}	_{27,787k (± 0.02%)}	_{-51k (- 0.18%)}	_27,765k	_27,809k	_{p=0.000 n=20}
_{Memory Allocs}	_{248,214 (± 0.06%)}	_{247,551 (± 0.06%)}	_{-663 (- 0.27%)}	_247,145	_248,596	_{p=0.000 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.012s (± 3.68%)}	_{0.012s (± 3.68%)}	_~	_0.010s	_0.013s	_{p=0.936 n=20}
_{Bind Time}	_{0.004s (±13.92%)}	_{0.004s (±13.12%)}	_~	_0.003s	_0.006s	_{p=0.779 n=20}
_{Check Time}	_{0.008s (± 6.07%)}	_{0.008s (± 4.91%)}	_~	_0.007s	_0.009s	_{p=0.721 n=20}
_{Emit Time}	_{0.009s (± 5.61%)}	_{0.009s (± 5.15%)}	_~	_0.007s	_0.010s	_{p=0.251 n=20}
_{Total Time}	_{0.033s (± 2.53%)}	_{0.033s (± 2.03%)}	_~	_0.030s	_0.035s	_{p=0.783 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	_878,390	_{-15,723 (- 1.76%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{939,035k (± 0.02%)}	_{935,616k (± 0.02%)}	_{-3,419k (- 0.36%)}	_935,067k	_936,416k	_{p=0.000 n=20}
_{Memory Allocs}	_{12,633,333 (± 0.02%)}	_{12,602,298 (± 0.02%)}	_{-31,035 (- 0.25%)}	_12,595,989	_12,612,937	_{p=0.000 n=20}
_{Config Time}	_0.002s	_0.002s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.148s (± 1.82%)}	_{0.150s (± 1.65%)}	_~	_0.143s	_0.161s	_{p=0.273 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.952s (± 1.74%)}	_{0.939s (± 0.88%)}	_~	_0.907s	_0.980s	_{p=0.203 n=20}
_{Emit Time}	_{0.501s (± 2.39%)}	_{0.508s (± 2.12%)}	_~	_0.468s	_0.537s	_{p=0.433 n=20}
_{Total Time}	_{1.697s (± 0.88%)}	_{1.692s (± 0.57%)}	_~	_1.644s	_1.722s	_{p=0.857 n=20}
_{mui-docs - native}
_Errors	_11,405	_11,405	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_3,784,019	_3,784,584	_{+565 (+ 0.01%)}	_~	_~	_{p=0.000 n=20}
_Types	_1,355,974	_1,281,353	_{🟩-74,621 (- 5.50%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{1,768,368k (± 0.07%)}	_{1,750,271k (± 0.06%)}	_{-18,097k (- 1.02%)}	_1,745,505k	_1,753,719k	_{p=0.000 n=20}
_{Memory Allocs}	_{25,773,701 (± 0.16%)}	_{25,563,297 (± 0.16%)}	_{-210,404 (- 0.82%)}	_25,461,390	_25,823,561	_{p=0.000 n=20}
_{Config Time}	_0.008s	_{0.008s (± 1.77%)}	_~	_0.008s	_0.009s	_{p=0.487 n=20}
_{Parse Time}	_{0.299s (± 2.20%)}	_{0.293s (± 2.11%)}	_~	_0.269s	_0.317s	_{p=0.239 n=20}
_{Bind Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{3.047s (± 0.89%)}	_{3.016s (± 0.91%)}	_~	_2.939s	_3.141s	_{p=0.098 n=20}
_{Emit Time}	_{0.246s (± 2.27%)}	_{0.242s (± 1.22%)}	_~	_0.234s	_0.256s	_{p=0.198 n=20}
_{Total Time}	_{4.092s (± 0.83%)}	_{4.053s (± 0.79%)}	_~	_3.974s	_4.206s	_{p=0.064 n=20}
_{sentry - native}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_4,793,245	_4,793,247	_{+2 (+ 0.00%)}	_~	_~	_{p=0.000 n=20}
_Types	_2,607,045	_2,504,214	_{🟩-102,831 (- 3.94%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{2,846,136k (± 0.03%)}	_{2,823,175k (± 0.02%)}	_{-22,961k (- 0.81%)}	_2,819,467k	_2,825,419k	_{p=0.000 n=20}
_{Memory Allocs}	_{75,183,057 (± 0.31%)}	_{74,775,458 (± 0.24%)}	_{-407,599 (- 0.54%)}	_74,372,796	_75,815,387	_{p=0.000 n=20}
_{Config Time}	_{0.026s (± 1.42%)}	_{0.025s (± 0.92%)}	_~	_0.025s	_0.026s	_{p=0.162 n=20}
_{Parse Time}	_{0.474s (± 5.13%)}	_{0.486s (± 4.65%)}	_~	_0.428s	_0.616s	_{p=0.256 n=20}
_{Bind Time}	_{0.192s (±12.21%)}	_{0.173s (±10.98%)}	_~	_0.131s	_0.238s	_{p=0.193 n=20}
_{Check Time}	_{6.672s (± 0.83%)}	_{6.658s (± 0.57%)}	_~	_6.556s	_6.922s	_{p=0.836 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{7.414s (± 0.75%)}	_{7.395s (± 0.55%)}	_~	_7.287s	_7.649s	_{p=0.847 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	_1,133,459	_{-24,709 (- 2.13%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{966,315k (± 0.02%)}	_{960,841k (± 0.02%)}	_{-5,474k (- 0.57%)}	_960,116k	_961,320k	_{p=0.000 n=20}
_{Memory Allocs}	_{13,500,137 (± 0.19%)}	_{13,456,450 (± 0.28%)}	_{-43,687 (- 0.32%)}	_13,382,649	_13,674,140	_{p=0.006 n=20}
_{Config Time}	_0.008s	_{0.008s (± 1.89%)}	_~	_0.007s	_0.009s	_{p=1.000 n=20}
_{Parse Time}	_{0.161s (± 3.05%)}	_{0.157s (± 2.06%)}	_~	_0.147s	_0.174s	_{p=0.303 n=20}
_{Bind Time}	_{0.044s (± 9.23%)}	_{0.049s (±10.11%)}	_~	_0.038s	_0.072s	_{p=0.059 n=20}
_{Check Time}	_{1.484s (± 0.94%)}	_{1.475s (± 1.10%)}	_~	_1.432s	_1.550s	_{p=0.234 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.714s (± 0.95%)}	_{1.708s (± 0.99%)}	_~	_1.665s	_1.792s	_{p=0.337 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	_420,367	_{🟩-18,596 (- 4.24%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{1,167,478k (± 0.30%)}	_{1,164,661k (± 0.41%)}	_~	_1,149,254k	_1,189,864k	_{p=0.114 n=20}
_{Memory Allocs}	_{47,594,740 (± 0.10%)}	_{47,226,404 (± 0.12%)}	_{-368,336 (- 0.77%)}	_47,055,025	_47,393,686	_{p=0.000 n=20}
_{Config Time}	_{0.002s (±19.09%)}	_{0.002s (±12.90%)}	_~	_0.001s	_0.002s	_{p=1.000 n=20}
_{Parse Time}	_{0.147s (± 2.41%)}	_{0.146s (± 2.30%)}	_~	_0.131s	_0.157s	_{p=0.605 n=20}
_{Bind Time}	_0.000s	_{0.000s (±208.60%)}	_~	_0.000s	_0.002s	_{p=1.000 n=20}
_{Check Time}	_{0.842s (± 0.82%)}	_{0.838s (± 0.72%)}	_~	_0.807s	_0.863s	_{p=0.507 n=20}
_{Emit Time}	_{0.148s (± 2.02%)}	_{0.150s (± 2.96%)}	_~	_0.139s	_0.175s	_{p=0.984 n=20}
_{Total Time}	_{9.823s (± 0.80%)}	_{9.788s (± 0.67%)}	_~	_9.466s	_10.024s	_{p=0.640 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	_188,476	_{🟩-7,640 (- 3.90%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{224,108k (± 0.02%)}	_{222,258k (± 0.02%)}	_{-1,851k (- 0.83%)}	_221,944k	_222,389k	_{p=0.000 n=20}
_{Memory Allocs}	_{2,389,514 (± 0.01%)}	_{2,371,413 (± 0.01%)}	_{-18,101 (- 0.76%)}	_2,369,701	_2,372,609	_{p=0.000 n=20}
_{Config Time}	_0.000s	_{0.000s (±208.60%)}	_~	_0.000s	_0.002s	_{p=1.000 n=20}
_{Parse Time}	_{0.049s (± 3.39%)}	_{0.053s (±12.74%)}	_~	_0.045s	_0.112s	_{p=0.662 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.389s (± 1.36%)}	_{0.388s (± 1.25%)}	_~	_0.370s	_0.407s	_{p=0.931 n=20}
_{Emit Time}	_{0.049s (± 4.11%)}	_{0.046s (± 4.95%)}	_{🟩-0.003s (- 6.19%)}	_0.041s	_0.056s	_{p=0.019 n=20}
_{Total Time}	_{0.517s (± 1.10%)}	_{0.515s (± 1.87%)}	_~	_0.492s	_0.589s	_{p=0.317 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	_2,958,636	_{-82,008 (- 2.70%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{2,424,794k (± 0.02%)}	_{2,406,867k (± 0.02%)}	_{-17,927k (- 0.74%)}	_2,405,370k	_2,409,730k	_{p=0.000 n=20}
_{Memory Allocs}	_{37,180,695 (± 0.08%)}	_{36,997,184 (± 0.09%)}	_{-183,511 (- 0.49%)}	_36,920,616	_37,214,194	_{p=0.000 n=20}
_{Config Time}	_0.003s	_{0.003s (±13.04%)}	_~	_0.003s	_0.007s	_{p=1.000 n=20}
_{Parse Time}	_{0.247s (± 2.06%)}	_{0.258s (± 4.77%)}	_~	_0.240s	_0.363s	_{p=0.057 n=20}
_{Bind Time}	_{0.098s (±12.62%)}	_{0.081s (± 7.87%)}	_~	_0.074s	_0.133s	_{p=0.099 n=20}
_{Check Time}	_{7.170s (± 0.41%)}	_{7.163s (± 0.61%)}	_~	_7.049s	_7.459s	_{p=0.569 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{7.529s (± 0.38%)}	_{7.516s (± 0.69%)}	_~	_7.384s	_7.915s	_{p=0.351 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	_395,397	_{-2,292 (- 0.58%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{326,076k (± 0.01%)}	_{325,549k (± 0.02%)}	_{-527k (- 0.16%)}	_325,282k	_325,775k	_{p=0.000 n=20}
_{Memory Allocs}	_{4,338,667 (± 0.17%)}	_{4,329,721 (± 0.17%)}	_{-8,946 (- 0.21%)}	_4,314,496	_4,358,698	_{p=0.012 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.039s (± 3.34%)}	_{0.040s (± 3.77%)}	_~	_0.034s	_0.044s	_{p=0.549 n=20}
_{Bind Time}	_{0.014s (±14.01%)}	_{0.014s (±10.05%)}	_~	_0.011s	_0.020s	_{p=0.369 n=20}
_{Check Time}	_{0.591s (± 0.78%)}	_{0.595s (± 3.21%)}	_~	_0.567s	_0.765s	_{p=0.351 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.664s (± 0.89%)}	_{0.668s (± 2.97%)}	_~	_0.643s	_0.845s	_{p=0.533 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	_173,731	_{🟩-7,464 (- 4.12%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{193,179k (± 0.01%)}	_{191,352k (± 0.01%)}	_{-1,827k (- 0.95%)}	_191,196k	_191,469k	_{p=0.000 n=20}
_{Memory Allocs}	_{1,310,748 (± 0.02%)}	_{1,292,859 (± 0.02%)}	_{-17,888 (- 1.36%)}	_1,292,183	_1,294,033	_{p=0.000 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.044s (± 2.32%)}	_{0.042s (± 3.04%)}	_~	_0.038s	_0.048s	_{p=0.070 n=20}
_{Bind Time}	_{0.021s (± 5.45%)}	_{0.021s (± 5.79%)}	_~	_0.017s	_0.027s	_{p=0.802 n=20}
_{Check Time}	_{0.293s (± 1.26%)}	_{0.292s (± 0.96%)}	_~	_0.281s	_0.299s	_{p=0.523 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.364s (± 0.99%)}	_{0.361s (± 0.77%)}	_~	_0.351s	_0.371s	_{p=0.322 n=20}
_{vscode - native}
_Errors	₁₁	₁₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_7,527,221	_7,527,221	_~	_~	_~	_{p=1.000 n=20}
_Types	_4,423,289	_4,210,551	_{🟩-212,738 (- 4.81%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{5,219,862k (± 0.02%)}	_{5,173,202k (± 0.01%)}	_{-46,660k (- 0.89%)}	_5,170,547k	_5,177,853k	_{p=0.000 n=20}
_{Memory Allocs}	_{57,151,077 (± 0.02%)}	_{56,675,452 (± 0.02%)}	_{-475,626 (- 0.83%)}	_56,650,387	_56,742,299	_{p=0.000 n=20}
_{Config Time}	_{0.034s (± 0.95%)}	_{0.035s (± 1.80%)}	_~	_0.032s	_0.038s	_{p=0.125 n=20}
_{Parse Time}	_{0.994s (± 2.32%)}	_{0.989s (± 2.64%)}	_~	_0.882s	_1.060s	_{p=0.867 n=20}
_{Bind Time}	_{0.335s (± 6.43%)}	_{0.360s (± 9.32%)}	_~	_0.297s	_0.577s	_{p=0.113 n=20}
_{Check Time}	_{8.144s (± 0.74%)}	_{8.142s (± 1.39%)}	_~	_7.669s	_8.639s	_{p=0.889 n=20}
_{Emit Time}	_{2.942s (± 4.71%)}	_{2.948s (± 5.09%)}	_~	_2.687s	_3.607s	_{p=0.673 n=20}
_{Total Time}	_{12.509s (± 1.10%)}	_{12.536s (± 1.22%)}	_~	_11.830s	_13.124s	_{p=0.673 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	_622,943	_{🟩-27,104 (- 4.17%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{697,612k (± 0.01%)}	_{691,102k (± 0.01%)}	_{-6,510k (- 0.93%)}	_690,760k	_691,548k	_{p=0.000 n=20}
_{Memory Allocs}	_{6,508,012 (± 0.06%)}	_{6,443,707 (± 0.05%)}	_{-64,305 (- 0.99%)}	_6,433,920	_6,456,184	_{p=0.000 n=20}
_{Config Time}	_0.004s	_0.004s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.134s (± 2.22%)}	_{0.135s (± 4.49%)}	_~	_0.111s	_0.161s	_{p=0.909 n=20}
_{Bind Time}	_{0.045s (± 9.16%)}	_{0.049s (±12.10%)}	_~	_0.038s	_0.071s	_{p=0.400 n=20}
_{Check Time}	_{1.018s (± 0.51%)}	_{1.008s (± 0.58%)}	_{-0.010s (- 0.96%)}	_0.990s	_1.029s	_{p=0.016 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.225s (± 0.73%)}	_{1.219s (± 0.64%)}	_~	_1.188s	_1.256s	_{p=0.365 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	_384,933	_{-3,051 (- 0.79%)}	_~	_~	_{p=0.000 n=20}
_{Memory Used}	_{349,478k (± 0.03%)}	_{348,805k (± 0.02%)}	_{-672k (- 0.19%)}	_348,656k	_349,226k	_{p=0.000 n=20}
_{Memory Allocs}	_{3,969,218 (± 0.07%)}	_{3,961,515 (± 0.06%)}	_{-7,703 (- 0.19%)}	_3,954,173	_3,977,377	_{p=0.000 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.061s (± 2.94%)}	_{0.060s (± 2.15%)}	_~	_0.056s	_0.065s	_{p=0.995 n=20}
_{Bind Time}	_{0.021s (±10.39%)}	_{0.021s (±11.34%)}	_~	_0.017s	_0.033s	_{p=0.775 n=20}
_{Check Time}	_{0.414s (± 0.82%)}	_{0.412s (± 0.91%)}	_~	_0.400s	_0.435s	_{p=0.329 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.501s (± 0.79%)}	_{0.500s (± 1.03%)}	_~	_0.484s	_0.526s	_{p=0.920 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 · 2026-10-30T16:59:56Z

Jake Bailey (@jakebailey) Here are the results of running the top 400 repos with tsc comparing baseline and pr:

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🟡 Changes recommended

The guard prematurely rejects unresolved generic variadic tuples that can normalize to never, potentially preventing key-property map creation and bypassing the discriminant shortcut in removeSubtypes.

1 open issue

Avoid rejecting generic tuples that normalize to never · New

What changed in this PR

This experiment aims to reduce unnecessary property-type resolution when the native TypeScript checker searches for unit-typed discriminant properties.

Changes:

Adds a shared predicate that skips methods and certain instantiated or mapped properties.
Uses the predicate in key-property discovery and union subtype reduction.

File	Description
`tsc/internal/checker/relater.go`	Defines the predicate and applies it to key-property candidate selection.
`tsc/internal/checker/checker.go`	Reuses the predicate when selecting discriminants for subtype reduction.

_{Review effort: Balanced}

+			// An object type other than a mapped type never instantiates to a unit type, so neither does a union containing one
+			if core.Some(uninstantiated.Distributed(), func(t *Type) bool {
+				return t.flags&TypeFlagsObject != 0 && t.objectFlags&ObjectFlagsMapped == 0


…le that can normalize to never

Avoid resolving property types that cannot be unit types when looking…

ae1bf6f

… for key properties

typescript-automation Bot added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Oct 30, 2026

Jake Bailey (jakebailey) added the Domain: Performance Reports of unusually slow behavior label Oct 30, 2026

Jake Bailey (jakebailey) requested a balanced review from Copilot October 30, 2026 17:03

Copilot started reviewing on behalf of Jake Bailey (jakebailey) October 30, 2026 17:04

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Copilot AI reviewed Oct 30, 2026

View reviewed changes

Keep resolving properties whose uninstantiated type has a generic tup…

ada8132

…le that can normalize to never

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[experiment] Avoid resolving property types that cannot be unit types when looking for key properties - #65056

[experiment] Avoid resolving property types that cannot be unit types when looking for key properties#65056
Mateusz Burzyński (Andarist) wants to merge 2 commits into
microsoft:mainfrom
Andarist:experiment/unit-property-fast-check

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