Respect parameter-initializer scope for body function declarations by Copilot · Pull Request #65299 · microsoft/TypeScript

Copilot · 2026-11-03T23:30:25Z

Analysis

Parameter-initializer scope filtering covered variables but excluded function symbols, allowing body functions to shadow outer bindings in checker API results.

const styles = { root: "outer" };
function read(value = styles.root) {
    function styles() {}
    return value;
}

The initializer’s styles should resolve to the outer variable, matching runtime behavior.

Fix

Resolution: Apply the existing, transform-aware parameter-scope check to function symbols.
Coverage: Add symbol, type, and diagnostic baselines for direct defaults, closures, destructuring, and missing outer bindings; preserve body and parameter lookup.

Copilot Checklist

I successfully ran the applicable command at the end of my session, and it completed without error:

npx hereby validate
npx hereby validate --api (for TypeScript API changes)

Fixes Native compiler API resolves a default-parameter reference to a body function binding #65090

Co-authored-by: RyanCavanaugh <6685088+RyanCavanaugh@users.noreply.github.com>

Ryan Cavanaugh (RyanCavanaugh) · 2026-11-04T01:08:18Z

TypeScript Bot (@typescript-bot) test it

typescript-automation · 2026-11-04T01:08:24Z

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 · 2026-11-04T01:43:34Z

Hey Ryan Cavanaugh (@RyanCavanaugh), the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

typescript-automation · 2026-11-04T01:47:40Z

Ryan Cavanaugh (@RyanCavanaugh) Here are the results of running the user tests with tsc comparing baseline and pr:

Everything looks good!

typescript-automation · 2026-11-04T02:00:44Z

Ryan Cavanaugh (@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 - 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}	_{106,403k (± 0.03%)}	_{106,394k (± 0.03%)}	_~	_106,251k	_106,532k	_{p=0.516 n=20}
_{Memory Allocs}	_{1,261,948 (± 0.01%)}	_{1,261,901 (± 0.01%)}	_~	_1,261,638	_1,262,139	_{p=0.461 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.023s (± 2.80%)}	_{0.023s (± 2.32%)}	_~	_0.021s	_0.025s	_{p=0.599 n=20}
_{Bind Time}	_{0.008s (± 4.45%)}	_{0.008s (± 4.18%)}	_~	_0.007s	_0.009s	_{p=0.091 n=20}
_{Check Time}	_{0.203s (± 1.43%)}	_{0.203s (± 0.67%)}	_~	_0.196s	_0.208s	_{p=0.652 n=20}
_{Emit Time}	_{0.130s (± 0.95%)}	_{0.130s (± 1.03%)}	_~	_0.126s	_0.137s	_{p=0.973 n=20}
_{Total Time}	_{0.367s (± 0.72%)}	_{0.367s (± 0.51%)}	_~	_0.361s	_0.378s	_{p=0.941 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}	_{510,853k (± 0.02%)}	_{510,791k (± 0.02%)}	_~	_510,444k	_511,362k	_{p=0.277 n=20}
_{Memory Allocs}	_{7,801,190 (± 0.19%)}	_{7,795,525 (± 0.14%)}	_~	_7,780,678	_7,878,629	_{p=0.583 n=20}
_{Config Time}	_{0.008s (± 2.10%)}	_{0.008s (± 2.33%)}	_~	_0.008s	_0.009s	_{p=1.000 n=20}
_{Parse Time}	_{0.124s (± 3.03%)}	_{0.125s (± 3.40%)}	_~	_0.113s	_0.155s	_{p=0.877 n=20}
_{Bind Time}	_{0.043s (±10.93%)}	_{0.043s (±10.44%)}	_~	_0.035s	_0.064s	_{p=0.550 n=20}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=20}
_{Emit Time}	_{0.622s (± 0.83%)}	_{0.625s (± 1.24%)}	_~	_0.609s	_0.672s	_{p=0.673 n=20}
_{Total Time}	_{0.809s (± 0.69%)}	_{0.814s (± 1.11%)}	_~	_0.785s	_0.876s	_{p=0.507 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}	_{476,027k (± 0.01%)}	_{476,035k (± 0.01%)}	_~	_475,841k	_476,227k	_{p=0.931 n=20}
_{Memory Allocs}	_{12,057,683 (± 0.01%)}	_{12,058,925 (± 0.01%)}	_~	_12,054,514	_12,068,475	_{p=0.265 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.041s (± 3.24%)}	_{0.041s (± 2.62%)}	_~	_0.036s	_0.046s	_{p=0.453 n=20}
_{Bind Time}	_{0.012s (± 8.43%)}	_{0.012s (± 8.38%)}	_~	_0.011s	_0.019s	_{p=0.474 n=20}
_{Check Time}	_{0.838s (± 1.66%)}	_{0.828s (± 0.57%)}	_~	_0.810s	_0.843s	_{p=0.213 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.918s (± 1.48%)}	_{0.909s (± 0.44%)}	_~	_0.896s	_0.921s	_{p=0.175 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}	_{27,749k (± 0.02%)}	_{27,756k (± 0.03%)}	_~	_27,719k	_27,795k	_{p=0.285 n=20}
_{Memory Allocs}	_{248,482 (± 0.09%)}	_{248,230 (± 0.06%)}	_~	_247,568	_248,938	_{p=0.133 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.012s (± 4.21%)}	_{0.012s (± 3.81%)}	_~	_0.009s	_0.013s	_{p=0.832 n=20}
_{Bind Time}	_{0.003s (±12.22%)}	_{0.003s (±11.26%)}	_~	_0.002s	_0.005s	_{p=0.697 n=20}
_{Check Time}	_{0.008s (± 5.69%)}	_{0.008s (± 6.42%)}	_~	_0.006s	_0.009s	_{p=0.988 n=20}
_{Emit Time}	_{0.007s (± 7.49%)}	_{0.007s (± 8.96%)}	_~	_0.006s	_0.011s	_{p=0.794 n=20}
_{Total Time}	_{0.031s (± 2.25%)}	_{0.031s (± 2.74%)}	_~	_0.028s	_0.035s	_{p=0.828 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}	_{941,630k (± 0.02%)}	_{941,619k (± 0.02%)}	_~	_940,596k	_942,514k	_{p=0.968 n=20}
_{Memory Allocs}	_{12,621,553 (± 0.02%)}	_{12,630,280 (± 0.05%)}	_{+8,727 (+ 0.07%)}	_12,616,089	_12,667,734	_{p=0.008 n=20}
_{Config Time}	_0.002s	_{0.002s (± 9.93%)}	_~	_0.002s	_0.004s	_{p=1.000 n=20}
_{Parse Time}	_{0.152s (± 2.54%)}	_{0.155s (± 2.67%)}	_~	_0.144s	_0.185s	_{p=0.317 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.900s (± 1.72%)}	_{0.910s (± 2.48%)}	_~	_0.845s	_1.045s	_{p=0.664 n=20}
_{Emit Time}	_{0.511s (± 3.33%)}	_{0.504s (± 2.32%)}	_~	_0.461s	_0.554s	_{p=0.836 n=20}
_{Total Time}	_{1.656s (± 1.65%)}	_{1.665s (± 1.61%)}	_~	_1.577s	_1.786s	_{p=0.525 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}	_{1,679,810k (± 0.06%)}	_{1,678,165k (± 0.07%)}	_~	_1,673,028k	_1,681,837k	_{p=0.052 n=20}
_{Memory Allocs}	_{25,725,128 (± 0.10%)}	_{25,728,502 (± 0.21%)}	_~	_25,555,714	_26,100,024	_{p=0.341 n=20}
_{Config Time}	_0.008s	_{0.008s (± 1.30%)}	_~	_0.008s	_0.009s	_{p=1.000 n=20}
_{Parse Time}	_{0.282s (± 2.93%)}	_{0.283s (± 2.77%)}	_~	_0.241s	_0.323s	_{p=0.386 n=20}
_{Bind Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{2.851s (± 0.59%)}	_{2.851s (± 0.60%)}	_~	_2.779s	_2.948s	_{p=0.888 n=20}
_{Emit Time}	_{0.241s (± 1.25%)}	_{0.239s (± 0.90%)}	_~	_0.232s	_0.246s	_{p=0.162 n=20}
_{Total Time}	_{3.858s (± 0.42%)}	_{3.861s (± 0.53%)}	_~	_3.787s	_3.961s	_{p=0.995 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}	_{2,798,886k (± 0.03%)}	_{2,800,162k (± 0.04%)}	_~	_2,795,698k	_2,806,338k	_{p=0.121 n=20}
_{Memory Allocs}	_{75,004,427 (± 0.19%)}	_{75,276,413 (± 0.32%)}	_~	_74,784,269	_76,213,209	_{p=0.253 n=20}
_{Config Time}	_{0.026s (± 7.91%)}	_{0.025s (± 1.08%)}	_~	_0.024s	_0.026s	_{p=0.786 n=20}
_{Parse Time}	_{0.468s (± 3.79%)}	_{0.475s (± 3.60%)}	_~	_0.418s	_0.536s	_{p=0.457 n=20}
_{Bind Time}	_{0.165s (±10.19%)}	_{0.171s (±10.68%)}	_~	_0.130s	_0.238s	_{p=0.804 n=20}
_{Check Time}	_{6.662s (± 0.55%)}	_{6.674s (± 0.79%)}	_~	_6.499s	_6.947s	_{p=0.973 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{7.376s (± 0.54%)}	_{7.398s (± 0.66%)}	_~	_7.165s	_7.636s	_{p=0.410 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}	_{952,795k (± 0.02%)}	_{952,950k (± 0.02%)}	_~	_952,124k	_954,014k	_{p=0.547 n=20}
_{Memory Allocs}	_{13,503,662 (± 0.20%)}	_{13,524,308 (± 0.24%)}	_~	_13,441,770	_13,739,182	_{p=0.265 n=20}
_{Config Time}	_{0.007s (± 2.39%)}	_{0.007s (± 3.17%)}	_~	_0.007s	_0.008s	_{p=0.155 n=20}
_{Parse Time}	_{0.155s (± 2.82%)}	_{0.154s (± 2.64%)}	_~	_0.143s	_0.182s	_{p=0.743 n=20}
_{Bind Time}	_{0.040s (± 8.72%)}	_{0.043s (±10.58%)}	_~	_0.035s	_0.063s	_{p=0.622 n=20}
_{Check Time}	_{1.379s (± 0.90%)}	_{1.384s (± 0.77%)}	_~	_1.331s	_1.429s	_{p=0.703 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.599s (± 0.69%)}	_{1.606s (± 0.68%)}	_~	_1.565s	_1.672s	_{p=0.344 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}	_{1,157,291k (± 0.24%)}	_{1,159,341k (± 0.37%)}	_~	_1,145,653k	_1,188,494k	_{p=0.820 n=20}
_{Memory Allocs}	_{47,601,263 (± 0.07%)}	_{47,534,616 (± 0.11%)}	_~	_47,374,278	_47,703,804	_{p=0.060 n=20}
_{Config Time}	_{0.002s (±20.02%)}	_{0.002s (±13.56%)}	_~	_0.001s	_0.003s	_{p=0.620 n=20}
_{Parse Time}	_{0.144s (± 4.28%)}	_{0.140s (± 1.55%)}	_~	_0.134s	_0.153s	_{p=0.440 n=20}
_{Bind Time}	_0.000s	_{0.000s (±208.60%)}	_~	_0.000s	_0.001s	_{p=1.000 n=20}
_{Check Time}	_{0.821s (± 0.92%)}	_{0.823s (± 0.80%)}	_~	_0.808s	_0.864s	_{p=0.507 n=20}
_{Emit Time}	_{0.145s (± 2.64%)}	_{0.145s (± 3.67%)}	_~	_0.136s	_0.181s	_{p=0.316 n=20}
_{Total Time}	_{9.608s (± 0.85%)}	_{9.563s (± 0.68%)}	_~	_9.326s	_10.022s	_{p=0.355 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}	_{221,499k (± 0.03%)}	_{221,537k (± 0.01%)}	_~	_221,388k	_221,652k	_{p=0.703 n=20}
_{Memory Allocs}	_{2,388,104 (± 0.01%)}	_{2,388,459 (± 0.02%)}	_~	_2,387,271	_2,390,568	_{p=0.327 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.050s (± 3.38%)}	_{0.051s (± 3.05%)}	_~	_0.046s	_0.057s	_{p=0.393 n=20}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Check Time}	_{0.381s (± 0.62%)}	_{0.382s (± 0.69%)}	_~	_0.372s	_0.395s	_{p=0.772 n=20}
_{Emit Time}	_{0.049s (± 6.38%)}	_{0.049s (± 5.46%)}	_~	_0.042s	_0.060s	_{p=0.662 n=20}
_{Total Time}	_{0.508s (± 0.87%)}	_{0.509s (± 0.81%)}	_~	_0.490s	_0.528s	_{p=0.615 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}	_{2,395,578k (± 0.03%)}	_{2,395,734k (± 0.02%)}	_~	_2,393,782k	_2,398,837k	_{p=0.529 n=20}
_{Memory Allocs}	_{37,165,437 (± 0.13%)}	_{37,146,702 (± 0.13%)}	_~	_37,057,879	_37,566,312	_{p=0.429 n=20}
_{Config Time}	_{0.003s (± 4.95%)}	_{0.003s (± 3.54%)}	_~	_0.002s	_0.003s	_{p=1.000 n=20}
_{Parse Time}	_{0.255s (± 1.50%)}	_{0.258s (± 2.54%)}	_~	_0.225s	_0.288s	_{p=0.255 n=20}
_{Bind Time}	_{0.084s (± 8.85%)}	_{0.085s (± 9.64%)}	_~	_0.073s	_0.141s	_{p=0.962 n=20}
_{Check Time}	_{5.779s (± 0.73%)}	_{5.763s (± 0.64%)}	_~	_5.666s	_5.920s	_{p=0.635 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{6.132s (± 0.72%)}	_{6.120s (± 0.64%)}	_~	_6.004s	_6.292s	_{p=0.703 n=20}
_{tanstack-router - native}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_570,149	_570,149	_~	_~	_~	_{p=1.000 n=20}
_Types	_396,551	_396,551	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{315,280k (± 0.01%)}	_{315,228k (± 0.02%)}	_~	_314,974k	_315,424k	_{p=0.208 n=20}
_{Memory Allocs}	_{4,328,948 (± 0.28%)}	_{4,327,428 (± 0.16%)}	_~	_4,311,977	_4,358,506	_{p=0.758 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.040s (± 2.71%)}	_{0.039s (± 4.44%)}	_~	_0.034s	_0.048s	_{p=0.109 n=20}
_{Bind Time}	_{0.011s (± 9.31%)}	_{0.013s (± 9.34%)}	_{🔻+0.001s (+13.33%)}	_0.010s	_0.017s	_{p=0.031 n=20}
_{Check Time}	_{0.458s (± 0.80%)}	_{0.462s (± 0.81%)}	_{+0.005s (+ 0.98%)}	_0.446s	_0.481s	_{p=0.033 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.526s (± 1.02%)}	_{0.532s (± 0.77%)}	_{+0.006s (+ 1.14%)}	_0.520s	_0.554s	_{p=0.009 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}	_{190,862k (± 0.02%)}	_{190,853k (± 0.01%)}	_~	_190,731k	_190,964k	_{p=0.703 n=20}
_{Memory Allocs}	_{1,309,789 (± 0.02%)}	_{1,310,139 (± 0.02%)}	_~	_1,309,154	_1,311,346	_{p=0.149 n=20}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.046s (± 5.40%)}	_{0.044s (± 3.17%)}	_~	_0.039s	_0.049s	_{p=0.341 n=20}
_{Bind Time}	_{0.022s (±12.96%)}	_{0.020s (± 3.74%)}	_~	_0.018s	_0.023s	_{p=0.740 n=20}
_{Check Time}	_{0.295s (± 2.39%)}	_{0.292s (± 0.99%)}	_~	_0.279s	_0.304s	_{p=0.920 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.368s (± 2.13%)}	_{0.363s (± 0.71%)}	_~	_0.351s	_0.372s	_{p=0.784 n=20}
_{vscode - native}
_Errors	₁₁	₁₁	_~	_~	_~	_{p=1.000 n=20}
_Symbols	_7,694,486	_7,694,486	_~	_~	_~	_{p=1.000 n=20}
_Types	_4,518,272	_4,518,272	_~	_~	_~	_{p=1.000 n=20}
_{Memory Used}	_{5,186,779k (± 0.01%)}	_{5,186,445k (± 0.02%)}	_~	_5,182,639k	_5,192,882k	_{p=0.253 n=20}
_{Memory Allocs}	_{58,044,157 (± 0.02%)}	_{58,058,484 (± 0.05%)}	_~	_58,018,524	_58,309,161	_{p=0.445 n=20}
_{Config Time}	_{0.034s (± 1.01%)}	_{0.034s (± 0.81%)}	_~	_0.033s	_0.035s	_{p=1.000 n=20}
_{Parse Time}	_{0.910s (± 1.56%)}	_{0.917s (± 1.67%)}	_~	_0.837s	_0.984s	_{p=0.723 n=20}
_{Bind Time}	_{0.307s (± 6.82%)}	_{0.301s (± 3.62%)}	_~	_0.286s	_0.394s	_{p=0.723 n=20}
_{Check Time}	_{7.512s (± 1.24%)}	_{7.542s (± 0.65%)}	_{+0.030s (+ 0.40%)}	_7.217s	_7.755s	_{p=0.048 n=20}
_{Emit Time}	_{2.098s (± 6.06%)}	_{2.049s (± 4.81%)}	_~	_1.938s	_2.840s	_{p=0.703 n=20}
_{Total Time}	_{10.920s (± 1.11%)}	_{10.903s (± 0.76%)}	_~	_10.692s	_11.406s	_{p=0.569 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}	_{638,921k (± 0.02%)}	_{638,938k (± 0.02%)}	_~	_638,651k	_639,342k	_{p=0.836 n=20}
_{Memory Allocs}	_{5,988,876 (± 0.05%)}	_{5,989,926 (± 0.04%)}	_~	_5,979,723	_5,998,926	_{p=0.478 n=20}
_{Config Time}	_0.004s	_0.004s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.121s (± 2.61%)}	_{0.120s (± 2.63%)}	_~	_0.107s	_0.130s	_{p=0.643 n=20}
_{Bind Time}	_{0.040s (± 9.81%)}	_{0.040s (±10.18%)}	_~	_0.032s	_0.063s	_{p=0.825 n=20}
_{Check Time}	_{1.063s (± 1.08%)}	_{1.054s (± 1.25%)}	_~	_1.017s	_1.115s	_{p=0.147 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{1.251s (± 0.99%)}	_{1.241s (± 1.05%)}	_~	_1.200s	_1.295s	_{p=0.213 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}	_{346,926k (± 0.02%)}	_{346,959k (± 0.02%)}	_~	_346,642k	_347,222k	_{p=0.507 n=20}
_{Memory Allocs}	_{3,998,561 (± 0.10%)}	_{3,999,513 (± 0.07%)}	_~	_3,991,070	_4,011,253	_{p=0.383 n=20}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=20}
_{Parse Time}	_{0.061s (± 3.61%)}	_{0.062s (± 3.99%)}	_~	_0.055s	_0.074s	_{p=0.814 n=20}
_{Bind Time}	_{0.023s (±10.58%)}	_{0.021s (±10.57%)}	_~	_0.017s	_0.033s	_{p=0.543 n=20}
_{Check Time}	_{0.450s (± 4.67%)}	_{0.442s (± 1.49%)}	_~	_0.426s	_0.472s	_{p=0.984 n=20}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=20}
_{Total Time}	_{0.541s (± 3.90%)}	_{0.532s (± 1.52%)}	_~	_0.509s	_0.572s	_{p=0.703 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 · 2026-11-04T02:39:15Z

Ryan Cavanaugh (@RyanCavanaugh) Here are the results of running the top 400 repos with tsc comparing baseline and pr:

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🟢 Approval recommended

No active review issues block approval of the parameter-initializer scope fix.

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What changed in this PR

Fixes #65090 by making the native compiler’s name resolution respect parameter-initializer scope: body function declarations no longer shadow outer bindings referenced by default parameters.

Changes:

Extends the existing parameter-scope filter to function symbols.
Adds regression coverage for direct defaults, closures, destructuring, and missing outer bindings, while preserving body, parameter, and named-function lookup.
Records expected symbol resolution, types, diagnostics, and JavaScript output.

File	Description
`tsc/testdata/tests/cases/compiler/defaultParameterBodyFunctionScope.ts`	Adds parameter-initializer scope regression cases.
`tsc/testdata/baselines/reference/compiler/defaultParameterBodyFunctionScope.types`	Records expected inferred types.
`tsc/testdata/baselines/reference/compiler/defaultParameterBodyFunctionScope.symbols`	Records references resolving to the correct declarations.
`tsc/testdata/baselines/reference/compiler/defaultParameterBodyFunctionScope.js`	Records emitted JavaScript for the test cases.
`tsc/testdata/baselines/reference/compiler/defaultParameterBodyFunctionScope.errors.txt`	Records the missing-name diagnostic when no outer binding exists.
`tsc/internal/binder/nameresolver.go`	Applies parameter-scope filtering to function symbols.

_{Review effort: Balanced}

Initial plan

42b18cb

Copilot AI assigned Copilot and Ryan Cavanaugh (RyanCavanaugh) Nov 3, 2026

typescript-automation Bot added Author: Team For Milestone Bug PRs that fix a bug with a specific milestone labels Nov 3, 2026

Copilot started work on behalf of Ryan Cavanaugh (RyanCavanaugh) November 3, 2026 23:30

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Copilot AI linked an issue Nov 3, 2026 that may be closed by this pull request

Native compiler API resolves a default-parameter reference to a body function binding #65090

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typescript-automation Bot added For Uncommitted Bug PR for untriaged, rejected, closed or missing bug and removed For Milestone Bug PRs that fix a bug with a specific milestone labels Nov 3, 2026

Copilot AI and others added 3 commits November 3, 2026 23:47

Add default-parameter body-function scope regression baselines

ccf9317

Co-authored-by: RyanCavanaugh <6685088+RyanCavanaugh@users.noreply.github.com>

Exclude body functions from parameter-initializer scope

44bc8f8

Co-authored-by: RyanCavanaugh <6685088+RyanCavanaugh@users.noreply.github.com>

Update parameter-initializer binding baselines

ca4737c

Co-authored-by: RyanCavanaugh <6685088+RyanCavanaugh@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Fix default parameter reference in native compiler API~~ Respect parameter-initializer scope for body function declarations Nov 4, 2026

Copilot finished work on behalf of Ryan Cavanaugh (RyanCavanaugh) November 4, 2026 00:13

Copilot AI requested a review from Ryan Cavanaugh (RyanCavanaugh) November 4, 2026 00:13

Ryan Cavanaugh (RyanCavanaugh) approved these changes Nov 4, 2026

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Ryan Cavanaugh (RyanCavanaugh) marked this pull request as ready for review November 4, 2026 16:11

Copilot AI balanced review requested due to automatic review settings November 4, 2026 16:11

Copilot started reviewing on behalf of Ryan Cavanaugh (RyanCavanaugh) November 4, 2026 16:12

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Jake Bailey (jakebailey) approved these changes Nov 4, 2026

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Copilot AI reviewed Nov 4, 2026

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Ryan Cavanaugh (RyanCavanaugh) added this pull request to the merge queue Nov 4, 2026

Merged via the queue into main with commit b8cc69c Nov 4, 2026
35 checks passed

Ryan Cavanaugh (RyanCavanaugh) deleted the copilot/resolve-default-parameter-issue branch November 4, 2026 16:49

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Respect parameter-initializer scope for body function declarations - #65299

Respect parameter-initializer scope for body function declarations#65299
Ryan Cavanaugh (RyanCavanaugh) merged 4 commits into
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copilot/resolve-default-parameter-issue

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