Reject visitor removal of required children by jakebailey · Pull Request #65288 · microsoft/TypeScript

Jake Bailey (jakebailey) · 2026-11-03T19:34:37Z

A visitor returning nil for a required child can leave an invalid tree that only crashes when a later consumer dereferences it. JSDoc import types expose this during type erasure even though emit never prints the affected nodes.

Required children must stay present when visited, while absent children from parser error recovery and optional-child/list elision remain valid.

A visitor returning nil for a required child can leave an invalid tree that only crashes when a later consumer dereferences it. JSDoc import types expose this during type erasure even though emit never prints the affected nodes. Required children must stay present when visited, while absent children from parser error recovery and optional-child/list elision remain valid.

The token case exercises the same path as an ordinary node, and the number annotation does not reproduce the import-type erasure bug.

Jake Bailey (jakebailey) · 2026-11-03T19:36:44Z

TypeScript Bot (@typescript-bot) perf test this faster

typescript-automation · 2026-11-03T19:36:50Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`perf test this faster`	✅ Started	👀 Results

Copilot

🟡 Changes recommended

Valid JavaScript with JSDoc-annotated properties or assignments can panic during emit because the type eraser removes required children from type wrappers instead of erasing the wrappers themselves.

1 open issue

Erase wrapped JSDoc types without removing required children · New

1 file not reviewed

tsc/internal/ast/ast_generated.go: Generated file

What changed in this PR

This PR strengthens the native compiler’s AST visitor contract by rejecting removal of existing required children, while allowing absent recovery nodes and optional-child/list elision.

Changes:

Add required-child checks to handwritten and generated visitors.
Adjust type erasure, declaration traversal, and token navigation to preserve the new invariant.
Add tests for required-child removal, permitted elision, and JSDoc import-type erasure.

File	Description
`tsc/internal/transformers/tstransforms/typeeraser.go`	Elide import types and clear export-assignment annotations.
`tsc/internal/transformers/tstransforms/typeeraser_test.go`	Test JSDoc import-type erasure on export assignments.
`tsc/internal/transformers/declarations/transform.go`	Preserve nodes when stopping traversal across `this` contexts.
`tsc/internal/astnav/tokens.go`	Preserve reparsed nodes skipped during token lookup.
`tsc/internal/ast/visitor.go`	Define and document the required-child guard.
`tsc/internal/ast/deepclone_test.go`	Test required-child rejection and permitted elision.
`tsc/internal/ast/ast.go`	Guard required children in handwritten visitors.
`tsc/internal/ast/ast_generated.go`	Apply guards throughout generated visitors.
`tools/scripts/tsc/generate-go-ast.ts`	Generate required-child checks from member metadata.

_{Review effort: Balanced}

typescript-automation · 2026-11-03T20:40:26Z

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	_79,607	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{106,428k (± 0.03%)}	_{106,399k (± 0.02%)}	_~	_106,338k	_106,501k	_{p=0.080 n=20}
_{Memory Allocs}	_{1,261,850 (± 0.01%)}	_{1,261,994 (± 0.01%)}	_~	_1,261,528	_1,262,556	_{p=0.052 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.023s (± 1.86%)}	_{0.023s (± 1.65%)}	_~	_0.021s	_0.024s	_{p=0.514 n=20}
_{Bind Time}	_{0.008s (± 5.52%)}	_{0.008s (± 3.78%)}	_~	_0.007s	_0.009s	_{p=0.150 n=20}
_{Check Time}	_{0.202s (± 0.69%)}	_{0.205s (± 0.80%)}	_{+0.002s (+ 1.09%)}	_0.198s	_0.210s	_{p=0.037 n=20}
_{Emit Time}	_{0.130s (± 0.58%)}	_{0.131s (± 0.65%)}	_~	_0.128s	_0.135s	_{p=0.311 n=20}
_{Total Time}	_{0.367s (± 0.44%)}	_{0.370s (± 0.49%)}	_~	_0.362s	_0.378s	_{p=0.063 n=20}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_586,317	_586,317	_~	_~	_~	_{p=1.000 n=20}
_Types	_241,457	_241,457	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{510,842k (± 0.02%)}	_{510,809k (± 0.02%)}	_~	_510,371k	_511,296k	_{p=0.693 n=20}
_{Memory Allocs}	_{7,790,744 (± 0.10%)}	_{7,795,148 (± 0.13%)}	_~	_7,777,863	_7,844,555	_{p=0.989 n=20}
_{Config Time}	_{0.008s (± 4.12%)}	_{0.008s (± 5.21%)}	_~	_0.008s	_0.012s	_{p=1.000 n=20}
_{Parse Time}	_{0.124s (± 3.20%)}	_{0.125s (± 2.79%)}	_~	_0.112s	_0.142s	_{p=0.490 n=20}
_{Bind Time}	_{0.042s (± 9.48%)}	_{0.042s (±10.47%)}	_~	_0.034s	_0.062s	_{p=0.316 n=20}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=20}
_{Emit Time}	_{0.619s (± 0.82%)}	_{0.620s (± 1.15%)}	_~	_0.608s	_0.669s	_{p=0.683 n=20}
_{Total Time}	_{0.805s (± 0.80%)}	_{0.807s (± 1.02%)}	_~	_0.783s	_0.839s	_{p=0.909 n=20}
_{arktype - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_686,116	_686,116	_~	_~	_~	_{p=1.000 n=20}
_Types	_939,797	_939,797	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{475,970k (± 0.01%)}	_{476,021k (± 0.01%)}	_{+51k (+ 0.01%)}	_475,756k	_476,160k	_{p=0.031 n=20}
_{Memory Allocs}	_{12,056,936 (± 0.01%)}	_{12,059,316 (± 0.02%)}	_~	_12,054,938	_12,070,382	_{p=0.114 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.041s (± 3.20%)}	_{0.041s (± 2.90%)}	_~	_0.037s	_0.047s	_{p=0.762 n=20}
_{Bind Time}	_{0.013s (± 8.85%)}	_{0.012s (± 9.11%)}	_{🟩-0.001s (- 7.84%)}	_0.010s	_0.018s	_{p=0.047 n=20}
_{Check Time}	_{0.835s (± 0.73%)}	_{0.844s (± 1.54%)}	_~	_0.803s	_0.913s	_{p=0.465 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.917s (± 0.65%)}	_{0.925s (± 1.31%)}	_~	_0.895s	_0.991s	_{p=0.551 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}	_{27,751k (± 0.02%)}	_{27,753k (± 0.03%)}	_~	_27,720k	_27,784k	_{p=0.644 n=20}
_{Memory Allocs}	_{248,204 (± 0.06%)}	_{248,444 (± 0.05%)}	_{+240 (+ 0.10%)}	_248,005	_249,104	_{p=0.012 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.012s (± 3.84%)}	_{0.012s (± 4.24%)}	_~	_0.009s	_0.013s	_{p=0.494 n=20}
_{Bind Time}	_{0.003s (± 9.64%)}	_{0.004s (±11.02%)}	_~	_0.002s	_0.005s	_{p=0.097 n=20}
_{Check Time}	_{0.008s (± 5.35%)}	_{0.007s (± 6.27%)}	_~	_0.006s	_0.009s	_{p=0.065 n=20}
_{Emit Time}	_{0.007s (± 7.50%)}	_{0.008s (± 6.99%)}	_~	_0.006s	_0.010s	_{p=0.141 n=20}
_{Total Time}	_{0.031s (± 2.72%)}	_{0.031s (± 2.86%)}	_~	_0.026s	_0.034s	_{p=0.791 n=20}
_{effect - native}
_Errors	₁₂	₁₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,235,134	_1,235,134	_~	_~	_~	_{p=1.000 n=20}
_Types	_893,436	_893,436	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{941,495k (± 0.02%)}	_{941,495k (± 0.02%)}	_~	_941,066k	_942,482k	_{p=0.738 n=20}
_{Memory Allocs}	_{12,623,962 (± 0.04%)}	_{12,628,198 (± 0.05%)}	_~	_12,614,410	_12,662,032	_{p=0.245 n=20}
_{Config Time}	_0.002s	_0.002s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.146s (± 1.45%)}	_{0.144s (± 1.87%)}	_~	_0.133s	_0.157s	_{p=0.279 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.852s (± 0.70%)}	_{0.856s (± 1.16%)}	_~	_0.832s	_0.916s	_{p=0.878 n=20}
_{Emit Time}	_{0.480s (± 1.78%)}	_{0.480s (± 1.65%)}	_~	_0.437s	_0.509s	_{p=0.784 n=20}
_{Total Time}	_{1.567s (± 0.44%)}	_{1.575s (± 0.67%)}	_~	_1.549s	_1.652s	_{p=0.223 n=20}
_{mui-docs - native}
_Errors	_11,405	_11,405	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_3,782,394	_3,782,394	_~	_~	_~	_{p=1.000 n=20}
_Types	_1,355,778	_1,355,778	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{1,679,315k (± 0.08%)}	_{1,679,737k (± 0.08%)}	_~	_1,674,388k	_1,685,890k	_{p=0.659 n=20}
_{Memory Allocs}	_{25,710,372 (± 0.14%)}	_{25,740,594 (± 0.13%)}	_~	_25,628,281	_25,905,985	_{p=0.081 n=20}
_{Config Time}	_{0.008s (± 2.79%)}	_{0.009s (± 2.78%)}	_~	_0.008s	_0.009s	_{p=0.527 n=20}
_{Parse Time}	_{0.294s (± 2.18%)}	_{0.289s (± 1.63%)}	_~	_0.276s	_0.314s	_{p=0.184 n=20}
_{Bind Time}	_{0.001s (±18.96%)}	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{2.939s (± 0.62%)}	_{2.949s (± 0.61%)}	_~	_2.881s	_3.009s	_{p=0.394 n=20}
_{Emit Time}	_{0.251s (± 1.77%)}	_{0.252s (± 2.65%)}	_~	_0.241s	_0.309s	_{p=0.712 n=20}
_{Total Time}	_{3.992s (± 0.51%)}	_{3.998s (± 0.56%)}	_~	_3.911s	_4.095s	_{p=0.753 n=20}
_{sentry - native}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_4,793,266	_4,793,266	_~	_~	_~	_{p=1.000 n=20}
_Types	_2,607,066	_2,607,066	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{2,799,500k (± 0.03%)}	_{2,798,633k (± 0.04%)}	_~	_2,795,292k	_2,803,576k	_{p=0.114 n=20}
_{Memory Allocs}	_{75,164,348 (± 0.33%)}	_{75,204,236 (± 0.23%)}	_~	_74,770,731	_75,844,746	_{p=0.565 n=20}
_{Config Time}	_{0.025s (± 1.54%)}	_{0.025s (± 1.53%)}	_~	_0.024s	_0.027s	_{p=0.728 n=20}
_{Parse Time}	_{0.478s (± 4.14%)}	_{0.462s (± 4.04%)}	_~	_0.420s	_0.587s	_{p=0.059 n=20}
_{Bind Time}	_{0.138s (± 9.07%)}	_{0.154s (±10.26%)}	_~	_0.122s	_0.219s	_{p=0.153 n=20}
_{Check Time}	_{6.466s (± 0.55%)}	_{6.483s (± 0.75%)}	_~	_6.338s	_6.800s	_{p=0.763 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{7.156s (± 0.52%)}	_{7.177s (± 0.70%)}	_~	_7.054s	_7.488s	_{p=0.784 n=20}
_{social-app - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_1,883,060	_1,883,060	_~	_~	_~	_{p=1.000 n=20}
_Types	_1,158,093	_1,158,093	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{952,634k (± 0.02%)}	_{952,742k (± 0.01%)}	_~	_952,218k	_953,236k	_{p=0.620 n=20}
_{Memory Allocs}	_{13,482,462 (± 0.16%)}	_{13,486,418 (± 0.12%)}	_~	_13,440,298	_13,547,055	_{p=0.429 n=20}
_{Config Time}	_{0.008s (± 2.67%)}	_{0.008s (± 2.91%)}	_~	_0.007s	_0.009s	_{p=0.734 n=20}
_{Parse Time}	_{0.157s (± 2.48%)}	_{0.156s (± 2.41%)}	_~	_0.141s	_0.173s	_{p=0.794 n=20}
_{Bind Time}	_{0.043s (± 8.47%)}	_{0.043s (± 8.54%)}	_~	_0.037s	_0.067s	_{p=0.701 n=20}
_{Check Time}	_{1.404s (± 0.75%)}	_{1.415s (± 1.20%)}	_~	_1.360s	_1.510s	_{p=0.394 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.631s (± 0.51%)}	_{1.642s (± 1.05%)}	_~	_1.588s	_1.756s	_{p=0.365 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	_438,823	_438,823	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{1,158,255k (± 0.25%)}	_{1,158,751k (± 0.21%)}	_~	_1,150,841k	_1,176,143k	_{p=0.799 n=20}
_{Memory Allocs}	_{47,622,621 (± 0.07%)}	_{47,633,567 (± 0.08%)}	_~	_47,507,450	_47,774,421	_{p=0.495 n=20}
_{Config Time}	_{0.002s (±16.60%)}	_{0.002s (±21.99%)}	_~	_0.000s	_0.003s	_{p=0.851 n=20}
_{Parse Time}	_{0.138s (± 1.48%)}	_{0.139s (± 1.43%)}	_~	_0.129s	_0.146s	_{p=0.606 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.783s (± 0.38%)}	_{0.789s (± 1.01%)}	_~	_0.774s	_0.858s	_{p=0.079 n=20}
_{Emit Time}	_{0.140s (± 1.74%)}	_{0.139s (± 1.24%)}	_~	_0.134s	_0.148s	_{p=0.206 n=20}
_{Total Time}	_{9.159s (± 0.38%)}	_{9.181s (± 0.47%)}	_~	_9.050s	_9.409s	_{p=0.457 n=20}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_263,481	_263,481	_~	_~	_~	_{p=1.000 n=20}
_Types	_196,103	_196,103	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{221,564k (± 0.02%)}	_{221,517k (± 0.02%)}	_~	_221,330k	_221,692k	_{p=0.080 n=20}
_{Memory Allocs}	_{2,388,806 (± 0.01%)}	_{2,388,755 (± 0.01%)}	_~	_2,387,492	_2,389,693	_{p=0.723 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.050s (± 2.64%)}	_{0.050s (± 3.14%)}	_~	_0.044s	_0.055s	_{p=0.867 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.363s (± 0.70%)}	_{0.364s (± 0.47%)}	_~	_0.357s	_0.369s	_{p=0.316 n=20}
_{Emit Time}	_{0.046s (± 4.62%)}	_{0.047s (± 5.13%)}	_~	_0.042s	_0.058s	_{p=0.204 n=20}
_{Total Time}	_{0.484s (± 0.51%)}	_{0.488s (± 0.68%)}	_~	_0.477s	_0.503s	_{p=0.087 n=20}
_{t3code-server - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_4,349,937	_4,349,937	_~	_~	_~	_{p=1.000 n=20}
_Types	_3,042,465	_3,042,465	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{2,395,551k (± 0.03%)}	_{2,395,363k (± 0.02%)}	_~	_2,393,689k	_2,397,186k	_{p=0.779 n=20}
_{Memory Allocs}	_{37,121,732 (± 0.06%)}	_{37,134,357 (± 0.08%)}	_~	_37,047,377	_37,286,439	_{p=0.529 n=20}
_{Config Time}	_{0.003s (± 6.00%)}	_{0.003s (± 6.84%)}	_~	_0.002s	_0.003s	_{p=1.000 n=20}
_{Parse Time}	_{0.247s (± 2.08%)}	_{0.246s (± 2.04%)}	_~	_0.228s	_0.266s	_{p=0.995 n=20}
_{Bind Time}	_{0.082s (± 8.94%)}	_{0.082s (± 9.80%)}	_~	_0.069s	_0.130s	_{p=0.702 n=20}
_{Check Time}	_{5.695s (± 1.07%)}	_{5.695s (± 1.13%)}	_~	_5.586s	_6.107s	_{p=0.560 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{6.039s (± 1.05%)}	_{6.037s (± 1.09%)}	_~	_5.934s	_6.444s	_{p=0.774 n=20}
_{tanstack-router - native}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_571,777	_571,777	_~	_~	_~	_{p=1.000 n=20}
_Types	_397,439	_397,439	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{316,846k (± 0.01%)}	_{316,802k (± 0.02%)}	_~	_316,548k	_316,946k	_{p=0.234 n=20}
_{Memory Allocs}	_{4,332,335 (± 0.21%)}	_{4,335,085 (± 0.14%)}	_~	_4,319,650	_4,366,626	_{p=0.121 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.042s (± 3.34%)}	_{0.041s (± 4.41%)}	_~	_0.035s	_0.048s	_{p=0.439 n=20}
_{Bind Time}	_{0.013s (±13.32%)}	_{0.012s (±12.54%)}	_~	_0.010s	_0.022s	_{p=0.686 n=20}
_{Check Time}	_{0.497s (± 1.06%)}	_{0.496s (± 0.91%)}	_~	_0.483s	_0.514s	_{p=0.644 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.569s (± 0.99%)}	_{0.567s (± 1.11%)}	_~	_0.545s	_0.595s	_{p=0.433 n=20}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_231,607	_231,607	_~	_~	_~	_{p=1.000 n=20}
_Types	_181,163	_181,163	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{190,856k (± 0.02%)}	_{190,879k (± 0.01%)}	_~	_190,778k	_190,956k	_{p=0.569 n=20}
_{Memory Allocs}	_{1,310,132 (± 0.02%)}	_{1,309,901 (± 0.01%)}	_~	_1,309,251	_1,310,634	_{p=0.163 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.044s (± 2.63%)}	_{0.043s (± 2.57%)}	_~	_0.039s	_0.047s	_{p=0.251 n=20}
_{Bind Time}	_{0.020s (± 6.77%)}	_{0.021s (± 5.66%)}	_~	_0.016s	_0.025s	_{p=0.200 n=20}
_{Check Time}	_{0.290s (± 0.98%)}	_{0.290s (± 1.04%)}	_~	_0.280s	_0.302s	_{p=0.963 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.360s (± 0.77%)}	_{0.360s (± 0.61%)}	_~	_0.351s	_0.368s	_{p=0.931 n=20}
_{vscode - native}
_Errors	₁₁	₁₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_7,638,911	_7,638,911	_~	_~	_~	_{p=1.000 n=20}
_Types	_4,468,638	_4,468,638	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{5,153,196k (± 0.02%)}	_{5,151,909k (± 0.02%)}	_~	_5,149,679k	_5,156,371k	_{p=0.068 n=20}
_{Memory Allocs}	_{57,628,779 (± 0.03%)}	_{57,614,355 (± 0.02%)}	_~	_57,591,072	_57,690,463	_{p=0.242 n=20}
_{Config Time}	_{0.033s (± 1.23%)}	_{0.033s (± 1.04%)}	_~	_0.033s	_0.035s	_{p=1.000 n=20}
_{Parse Time}	_{0.895s (± 2.14%)}	_{0.896s (± 1.39%)}	_~	_0.813s	_0.939s	_{p=0.606 n=20}
_{Bind Time}	_{0.301s (± 8.24%)}	_{0.300s (± 7.82%)}	_~	_0.273s	_0.475s	_{p=0.877 n=20}
_{Check Time}	_{6.909s (± 1.01%)}	_{6.980s (± 0.87%)}	_{+0.070s (+ 1.02%)}	_6.819s	_7.353s	_{p=0.031 n=20}
_{Emit Time}	_{2.068s (± 7.43%)}	_{1.919s (± 4.74%)}	_{🟩-0.149s (- 7.22%)}	_1.846s	_2.730s	_{p=0.044 n=20}
_{Total Time}	_{10.266s (± 1.47%)}	_{10.184s (± 1.10%)}	_~	_9.963s	_10.928s	_{p=0.565 n=20}
_{webpack - native}
_Errors	₆₁₁	₆₁₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_879,524	_879,524	_~	_~	_~	_{p=1.000 n=20}
_Types	_612,242	_612,242	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{638,981k (± 0.01%)}	_{639,064k (± 0.02%)}	_~	_638,657k	_639,620k	_{p=0.159 n=20}
_{Memory Allocs}	_{5,989,949 (± 0.05%)}	_{5,991,892 (± 0.08%)}	_~	_5,982,702	_6,024,368	_{p=0.820 n=20}
_{Config Time}	_0.004s	_0.004s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.130s (± 2.03%)}	_{0.133s (± 3.10%)}	_~	_0.122s	_0.161s	_{p=0.550 n=20}
_{Bind Time}	_{0.046s (± 9.76%)}	_{0.044s (± 6.43%)}	_~	_0.037s	_0.057s	_{p=0.867 n=20}
_{Check Time}	_{1.196s (± 1.52%)}	_{1.197s (± 1.58%)}	_~	_1.081s	_1.276s	_{p=0.973 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.401s (± 1.23%)}	_{1.403s (± 1.22%)}	_~	_1.311s	_1.477s	_{p=0.963 n=20}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_644,330	_644,330	_~	_~	_~	_{p=1.000 n=20}
_Types	_392,175	_392,175	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{346,997k (± 0.03%)}	_{347,038k (± 0.03%)}	_~	_346,725k	_347,578k	_{p=0.723 n=20}
_{Memory Allocs}	_{4,002,767 (± 0.15%)}	_{4,000,551 (± 0.09%)}	_~	_3,988,432	_4,015,133	_{p=0.968 n=20}
_{Config Time}	_0.001s	_{0.001s (±18.96%)}	_~	_0.001s	_0.003s	_{p=1.000 n=20}
_{Parse Time}	_{0.069s (± 3.13%)}	_{0.072s (±10.50%)}	_~	_0.063s	_0.139s	_{p=0.634 n=20}
_{Bind Time}	_{0.020s (± 6.92%)}	_{0.021s (±10.38%)}	_~	_0.017s	_0.035s	_{p=0.372 n=20}
_{Check Time}	_{0.452s (± 1.66%)}	_{0.464s (± 2.23%)}	_~	_0.436s	_0.511s	_{p=0.125 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.548s (± 1.60%)}	_{0.565s (± 2.85%)}	_~	_0.525s	_0.680s	_{p=0.066 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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Reparsed JSDoc annotations on object properties and assignments can contain wrapper types with required children. Descending into those wrappers during type erasure removes their children and trips the required-child visitor invariant.

The merged schema now permits index signatures without annotations. Regenerating the visitor keeps its required-child checks aligned with that schema and avoids generation drift in the PR merge result.

Jake Bailey (jakebailey) added 2 commits November 3, 2026 10:43

Trim redundant visitor regression cases

b4176f3

The token case exercises the same path as an ordinary node, and the number annotation does not reproduce the import-type erasure bug.

Copilot AI balanced review requested due to automatic review settings November 3, 2026 19:34

github-project-automation Bot added this to PR Backlog Nov 3, 2026

github-project-automation Bot moved this to Not started in PR Backlog Nov 3, 2026

typescript-automation Bot assigned Jake Bailey (jakebailey) Nov 3, 2026

typescript-automation Bot added Author: Team For Uncommitted Bug PR for untriaged, rejected, closed or missing bug labels Nov 3, 2026

Copilot started reviewing on behalf of Jake Bailey (jakebailey) November 3, 2026 19:43

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Comment thread tsc/internal/transformers/tstransforms/typeeraser.go Resolved

Ryan Cavanaugh (RyanCavanaugh) approved these changes Nov 3, 2026

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github-project-automation Bot moved this from Not started to Needs merge in PR Backlog Nov 3, 2026

Jake Bailey (jakebailey) enabled auto-merge November 3, 2026 21:45

Jake Bailey (jakebailey) added 2 commits November 3, 2026 13:47

Merge remote-tracking branch 'upstream/main' into visitor-nil-hole

6e88bb2

Regenerate visitors for optional index-signature types

d3e9b6b

The merged schema now permits index signatures without annotations. Regenerating the visitor keeps its required-child checks aligned with that schema and avoids generation drift in the PR merge result.

Jake Bailey (jakebailey) requested a review from Ryan Cavanaugh (RyanCavanaugh) November 3, 2026 22:09

Jake Bailey (jakebailey) disabled auto-merge November 3, 2026 22:29

Jake Bailey (jakebailey) enabled auto-merge November 3, 2026 22:30

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Reject visitor removal of required children - #65288

Reject visitor removal of required children#65288
Jake Bailey (jakebailey) wants to merge 5 commits into
microsoft:mainfrom
jakebailey:visitor-nil-hole

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Jake Bailey (jakebailey) commented Nov 3, 2026

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