Fix crash in CFA when for loop initializer throws by Andarist · Pull Request #63108 · microsoft/TypeScript

Mateusz Burzyński (Andarist) · 2026-02-05T20:11:38Z

Daniel Rosenwasser (DanielRosenwasser) · 2026-02-06T06:31:51Z

@tyepscript-bot test it

Daniel Rosenwasser (DanielRosenwasser) · 2026-02-06T06:34:29Z

lmao what https://github.com/microsoft/TypeScript/wiki/Triggering-TypeScript-Bot/a9168073a450877883d68704dc746cfaf4094559

Daniel Rosenwasser (DanielRosenwasser) · 2026-02-06T06:34:38Z

TypeScript Bot (@typescript-bot) test it

TypeScript Bot (typescript-bot) · 2026-02-06T06:34:44Z

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 (typescript-bot) · 2026-02-06T06:57:00Z

Hey Daniel Rosenwasser (@DanielRosenwasser), the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

TypeScript Bot (typescript-bot) · 2026-02-06T07:04:34Z

Daniel Rosenwasser (@DanielRosenwasser) Here are the results of running the user tests with tsc comparing main and refs/pull/63108/merge:

There were infrastructure failures potentially unrelated to your change:

1 instance of "Git clone failed"

Otherwise...

Everything looks good!

TypeScript Bot (typescript-bot) · 2026-02-06T07:32:40Z

Daniel Rosenwasser (@DanielRosenwasser)
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	₃	₃	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_82,521	_82,521	_~	_~	_~	_{p=1.000 n=6}
_Types	_125,280	_125,280	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{276,733k (± 0.67%)}	_{274,511k (± 0.06%)}	_~	_274,319k	_274,699k	_{p=0.230 n=6}
_{Parse Time}	_{1.31s (± 0.79%)}	_{1.31s (± 0.31%)}	_~	_1.30s	_1.31s	_{p=0.924 n=6}
_{Bind Time}	_0.75s	_{0.75s (± 0.54%)}	_~	_0.75s	_0.76s	_{p=0.405 n=6}
_{Check Time}	_{14.09s (± 0.35%)}	_{14.08s (± 0.21%)}	_~	_14.04s	_14.11s	_{p=0.746 n=6}
_{Emit Time}	_{2.64s (± 0.50%)}	_{2.64s (± 0.50%)}	_~	_2.62s	_2.66s	_{p=0.607 n=6}
_{Total Time}	_{18.79s (± 0.30%)}	_{18.78s (± 0.09%)}	_~	_18.76s	_18.80s	_{p=0.936 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_955,823	_955,823	_~	_~	_~	_{p=1.000 n=6}
_Types	_415,853	_415,853	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{1,254,966k (± 0.01%)}	_{1,254,922k (± 0.01%)}	_~	_1,254,839k	_1,255,034k	_{p=0.810 n=6}
_{Parse Time}	_{7.94s (± 0.87%)}	_{8.03s (± 0.33%)}	_~	_7.98s	_8.05s	_{p=0.052 n=6}
_{Bind Time}	_{2.38s (± 0.93%)}	_{2.41s (± 0.97%)}	_~	_2.37s	_2.44s	_{p=0.104 n=6}
_{Check Time}	_{38.78s (± 0.30%)}	_{38.91s (± 0.44%)}	_~	_38.62s	_39.12s	_{p=0.128 n=6}
_{Emit Time}	_{17.92s (± 0.50%)}	_{17.88s (± 0.65%)}	_~	_17.78s	_18.10s	_{p=0.378 n=6}
_{Total Time}	_{67.02s (± 0.30%)}	_{67.23s (± 0.21%)}	_~	_67.07s	_67.48s	_{p=0.128 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	_11,439	_11,439	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,703,113	_2,703,113	_~	_~	_~	_{p=1.000 n=6}
_Types	_931,060	_931,060	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{3,039,102k (± 0.00%)}	_{3,039,096k (± 0.00%)}	_~	_3,038,963k	_3,039,315k	_{p=0.936 n=6}
_{Parse Time}	_{8.52s (± 0.30%)}	_{8.52s (± 0.13%)}	_~	_8.51s	_8.53s	_{p=1.000 n=6}
_{Bind Time}	_{2.31s (± 0.27%)}	_{2.31s (± 0.39%)}	_~	_2.30s	_2.32s	_{p=1.000 n=6}
_{Check Time}	_{92.86s (± 0.52%)}	_{92.83s (± 0.15%)}	_~	_92.65s	_92.97s	_{p=0.810 n=6}
_{Emit Time}	_{0.32s (± 1.74%)}	_{0.32s (± 1.74%)}	_~	_0.31s	_0.32s	_{p=1.000 n=6}
_{Total Time}	_{104.00s (± 0.48%)}	_{103.97s (± 0.13%)}	_~	_103.78s	_104.13s	_{p=0.810 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,252,789	_1,252,789	_~	_~	_~	_{p=1.000 n=6}
_Types	_259,991	_259,991	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,394,074k (± 0.02%)}	_{2,454,922k (± 6.06%)}	_~	_2,393,635k	_2,758,901k	_{p=0.471 n=6}
_{Parse Time}	_{5.17s (± 1.17%)}	_{5.12s (± 0.97%)}	_~	_5.07s	_5.21s	_{p=0.149 n=6}
_{Bind Time}	_{1.84s (± 1.22%)}	_{1.83s (± 1.32%)}	_~	_1.81s	_1.87s	_{p=0.743 n=6}
_{Check Time}	_{35.54s (± 0.26%)}	_{35.54s (± 0.64%)}	_~	_35.15s	_35.80s	_{p=0.810 n=6}
_{Emit Time}	_{3.01s (± 0.58%)}	_{3.02s (± 1.08%)}	_~	_2.97s	_3.06s	_{p=0.520 n=6}
_{Total Time}	_{45.60s (± 0.28%)}	_{45.55s (± 0.40%)}	_~	_45.26s	_45.75s	_{p=0.748 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,252,789	_1,252,789	_~	_~	_~	_{p=1.000 n=6}
_Types	_259,991	_259,991	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{3,190,283k (± 0.02%)}	_{2,948,170k (±12.69%)}	_~	_2,464,339k	_3,190,639k	_{p=0.173 n=6}
_{Parse Time}	_{6.79s (± 1.29%)}	_{6.80s (± 1.54%)}	_~	_6.65s	_6.92s	_{p=0.810 n=6}
_{Bind Time}	_{2.24s (± 1.25%)}	_{2.26s (± 1.44%)}	_~	_2.22s	_2.31s	_{p=0.296 n=6}
_{Check Time}	_{43.05s (± 0.32%)}	_{43.07s (± 0.48%)}	_~	_42.75s	_43.32s	_{p=0.810 n=6}
_{Emit Time}	_{3.44s (± 1.73%)}	_{3.47s (± 2.16%)}	_~	_3.39s	_3.57s	_{p=0.336 n=6}
_{Total Time}	_{55.53s (± 0.30%)}	_{55.62s (± 0.54%)}	_~	_55.20s	_55.87s	_{p=0.378 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_264,703	_264,703	_~	_~	_~	_{p=1.000 n=6}
_Types	_104,091	_104,091	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{443,675k (± 0.01%)}	_{443,663k (± 0.01%)}	_~	_443,609k	_443,725k	_{p=0.810 n=6}
_{Parse Time}	_{4.33s (± 0.52%)}	_{4.34s (± 0.62%)}	_~	_4.30s	_4.37s	_{p=0.370 n=6}
_{Bind Time}	_{1.71s (± 0.81%)}	_{1.68s (± 1.27%)}	_{-0.03s (- 1.56%)}	_1.64s	_1.70s	_{p=0.029 n=6}
_{Check Time}	_{23.77s (± 0.31%)}	_{23.76s (± 0.29%)}	_~	_23.67s	_23.86s	_{p=0.810 n=6}
_{Emit Time}	_{1.93s (± 1.38%)}	_{1.92s (± 0.85%)}	_~	_1.90s	_1.95s	_{p=0.935 n=6}
_{Total Time}	_{31.73s (± 0.26%)}	_{31.71s (± 0.30%)}	_~	_31.56s	_31.81s	_{p=0.936 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₂₇₁	₂₇₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_225,118	_225,118	_~	_~	_~	_{p=1.000 n=6}
_Types	_93,554	_93,554	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{370,533k (± 0.02%)}	_{370,559k (± 0.01%)}	_~	_370,503k	_370,638k	_{p=0.575 n=6}
_{Parse Time}	_{2.83s (± 1.16%)}	_{2.82s (± 0.81%)}	_~	_2.79s	_2.84s	_{p=0.569 n=6}
_{Bind Time}	_{1.63s (± 0.78%)}	_{1.65s (± 2.09%)}	_~	_1.60s	_1.70s	_{p=0.280 n=6}
_{Check Time}	_{17.38s (± 0.35%)}	_{17.40s (± 0.25%)}	_~	_17.34s	_17.46s	_{p=0.574 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{21.84s (± 0.39%)}	_{21.87s (± 0.18%)}	_~	_21.83s	_21.93s	_{p=0.688 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₁₁	₁₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_4,221,104	_4,221,104	_~	_~	_~	_{p=1.000 n=6}
_Types	_1,340,209	_1,340,209	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{4,015,297k (± 0.00%)}	_{4,015,300k (± 0.00%)}	_~	_4,015,142k	_4,015,488k	_{p=0.810 n=6}
_{Parse Time}	_{16.21s (± 0.32%)}	_{16.52s (± 3.25%)}	_{+0.32s (+ 1.94%)}	_16.20s	_17.61s	_{p=0.045 n=6}
_{Bind Time}	_{5.49s (± 0.71%)}	_{5.50s (± 0.46%)}	_~	_5.48s	_5.55s	_{p=0.520 n=6}
_{Check Time}	_{121.88s (± 4.41%)}	_{119.26s (± 2.22%)}	_~	_115.93s	_123.50s	_{p=0.378 n=6}
_{Emit Time}	_{53.25s (±15.86%)}	_{55.24s (±13.02%)}	_~	_45.57s	_62.96s	_{p=0.810 n=6}
_{Total Time}	_{196.83s (± 4.53%)}	_{196.53s (± 2.98%)}	_~	_190.45s	_204.25s	_{p=0.810 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₄₁	₄₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_402,249	_402,249	_~	_~	_~	_{p=1.000 n=6}
_Types	_178,120	_178,120	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{559,133k (± 0.02%)}	_{559,017k (± 0.01%)}	_{-115k (- 0.02%)}	_558,905k	_559,107k	_{p=0.031 n=6}
_{Parse Time}	_{4.76s (± 0.55%)}	_{4.76s (± 0.76%)}	_~	_4.71s	_4.82s	_{p=0.570 n=6}
_{Bind Time}	_{2.04s (± 1.34%)}	_{2.03s (± 2.17%)}	_~	_1.99s	_2.11s	_{p=0.746 n=6}
_{Check Time}	_{24.31s (± 1.41%)}	_{24.38s (± 0.39%)}	_~	_24.20s	_24.46s	_{p=0.689 n=6}
_{Emit Time}	_{0.00s (±154.76%)}	_{0.01s (±109.43%)}	_~	_0.00s	_0.01s	_{p=0.640 n=6}
_{Total Time}	_{31.11s (± 1.10%)}	_{31.18s (± 0.40%)}	_~	_30.95s	_31.30s	_{p=1.000 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₃₀	₃₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_731,941	_731,941	_~	_~	_~	_{p=1.000 n=6}
_Types	_219,279	_219,279	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{635,987k (± 0.01%)}	_{635,897k (± 0.01%)}	_{-90k (- 0.01%)}	_635,829k	_635,937k	_{p=0.020 n=6}
_{Parse Time}	_{4.59s (± 0.51%)}	_{4.59s (± 0.80%)}	_~	_4.55s	_4.65s	_{p=0.869 n=6}
_{Bind Time}	_{1.50s (± 0.42%)}	_{1.50s (± 1.17%)}	_~	_1.47s	_1.51s	_{p=0.866 n=6}
_{Check Time}	_{22.17s (± 0.31%)}	_{22.18s (± 0.52%)}	_~	_22.04s	_22.33s	_{p=0.748 n=6}
_{Emit Time}	_{0.00s (±244.70%)}	_0.00s	_~	_~	_~	_{p=0.405 n=6}
_{Total Time}	_{28.26s (± 0.23%)}	_{28.27s (± 0.36%)}	_~	_28.11s	_28.36s	_{p=0.688 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 (typescript-bot) · 2026-02-06T07:56:52Z

Daniel Rosenwasser (@DanielRosenwasser) Here are the results of running the top 400 repos with tsc comparing main and refs/pull/63108/merge:

Everything looks good!

TypeScript Bot (typescript-bot) · 2026-03-24T21:23:35Z

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

Mateusz Burzyński (Andarist) added 6 commits February 5, 2026 14:39

add tests

629847d

add reentry mitigation

f0aeeeb

update tests

aa5b116

target fix in the binder

1ed6890

improve comment

805972d

add test

76f2f2f

github-project-automation Bot added this to PR Backlog Feb 5, 2026

github-project-automation Bot moved this to Not started in PR Backlog Feb 5, 2026

TypeScript Bot (typescript-bot) added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Feb 5, 2026

TypeScript Bot (typescript-bot) added For Backlog Bug PRs that fix a backlog bug and removed For Uncommitted Bug PR for untriaged, rejected, closed or missing bug labels Feb 13, 2026

TypeScript Bot (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 crash in CFA when for loop initializer throws - #63108

Fix crash in CFA when for loop initializer throws#63108
Mateusz Burzyński (Andarist) wants to merge 6 commits into
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Andarist:fix/crash-cfa-throw-for-head

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