Fixed signature caching issue caused by reentrant signature checking by Andarist · Pull Request #64077 · microsoft/TypeScript

Mateusz Burzyński (Andarist) · 2026-08-28T16:43:30Z

fixes #63949 by porting #60208 (that's basically put in the first commit in this PR).

This is basically the same as #64014 but it comes with an extra commit that doesn't regress this case:

declare const example: (f: (a: string) => number) => string;

const f = (a: string) => g();

const g = () => {
    return example(f);
};

The above should error but by porting #60208 alone, it stops doing that.

In fact, the second commit is enough to fix #63949 , the porting commit is not strictly needed for this - but I decided to keep it here as part of the Corsa-Strada alignment efforts

…inapplicable reentrant calls.

Mateusz Burzyński (Andarist) · 2026-08-28T16:44:15Z

+    return executeFetch("x", /*argument*/data);
+}, []);
+export const check: Promise<string> = cb({ v: 1 });`
+	for _, first := range []string{"callback", "argument", "diagnostics"} {


In here, I just make sure the cached signatures stay the same regardless of the order of the LSP requests

Copilot

Pull request overview

Prevents reentrant signature resolution from using a function’s inferred return type as contextual evidence for its own body.

Changes:

Adds the self-signature guard in contextual return-type resolution.
Adds compiler and Fourslash regression coverage.
Updates affected type, symbol, and diagnostic baselines.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
`tsc/internal/checker/checker.go`	Excludes a function’s own signature from contextual return typing.
`tsc/internal/fourslash/tests/quickInfoGenericDefaultInReentrantCallResolution_test.go`	Tests stable diagnostics and quick info across request orders.
`tsc/testdata/tests/cases/compiler/genericDefaultInReentrantCallResolution.ts`	Reproduces issue #63949.
`tsc/testdata/tests/cases/compiler/reentrantCallDoesNotReuseInapplicableCachedSignature.ts`	Covers the related invalid-call regression.
`tsc/testdata/baselines/reference/compiler/genericDefaultInReentrantCallResolution.types`	Records corrected inferred types.
`tsc/testdata/baselines/reference/compiler/genericDefaultInReentrantCallResolution.symbols`	Records symbols for the regression case.
`tsc/testdata/baselines/reference/compiler/reentrantCallDoesNotReuseInapplicableCachedSignature.types`	Records expected types for the error case.
`tsc/testdata/baselines/reference/compiler/reentrantCallDoesNotReuseInapplicableCachedSignature.symbols`	Records expected symbols for the error case.
`tsc/testdata/baselines/reference/compiler/reentrantCallDoesNotReuseInapplicableCachedSignature.errors.txt`	Verifies the expected assignability diagnostic.
`tsc/testdata/baselines/reference/conformance/neverReturningFunctions1.types`	Updates affected literal widening.
`tsc/testdata/baselines/reference/conformance/intraExpressionInferencesJsx.types`	Updates affected JSX inference baselines.

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Mateusz Burzyński (Andarist) · 2026-08-28T16:46:57Z

@@ -143,10 +143,10 @@ const Component = <T extends Animations>({
 >func : () => { a: true; }

        return {
->{          a: true,        } : { a: true; }


I think those are correct, the inferred signature here includes boolean and then that object became checked with that as its contextual part so a true literal became here contextually-typed by a boolean and that makes it to retain the true type (instead of widening to boolean)

Jake Bailey (jakebailey) · 2026-10-13T22:51:22Z

TypeScript Bot (@typescript-bot) test it

typescript-automation · 2026-10-13T22:51:28Z

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 · 2026-10-13T23:14:45Z

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 · 2026-10-13T23:21:42Z

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=12}
_Symbols	_115,276	_115,276	_~	_~	_~	_{p=1.000 n=12}
_Types	_79,613	_79,613	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{133,205k (± 0.06%)}	_{133,215k (± 0.06%)}	_~	_132,979k	_133,404k	_{p=0.755 n=12}
_{Memory Allocs}	_{2,190,194 (± 0.00%)}	_{2,190,268 (± 0.00%)}	_~	_2,190,145	_2,190,604	_{p=0.671 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.048s (± 2.85%)}	_{0.049s (± 4.81%)}	_~	_0.044s	_0.056s	_{p=0.617 n=12}
_{Bind Time}	_{0.015s (±12.65%)}	_{0.016s (±13.19%)}	_~	_0.012s	_0.022s	_{p=0.985 n=12}
_{Check Time}	_{0.605s (± 0.49%)}	_{0.595s (± 0.87%)}	_{-0.010s (- 1.60%)}	_0.584s	_0.607s	_{p=0.002 n=12}
_{Emit Time}	_{0.327s (± 2.17%)}	_{0.321s (± 2.06%)}	_~	_0.308s	_0.346s	_{p=0.117 n=12}
_{Total Time}	_{1.002s (± 0.79%)}	_{0.989s (± 0.78%)}	_{-0.013s (- 1.34%)}	_0.970s	_1.014s	_{p=0.020 n=12}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_{845,225 (± 0.05%)}	_{845,823 (± 0.03%)}	_{+598 (+ 0.07%)}	_845,098	_846,636	_{p=0.024 n=12}
_Types	_{248,124 (± 0.00%)}	_{248,124 (± 0.00%)}	_~	_248,122	_248,127	_{p=0.354 n=12}
_{Memory Used}	_{746,018k (± 0.02%)}	_{746,192k (± 0.01%)}	_{+174k (+ 0.02%)}	_745,956k	_746,551k	_{p=0.033 n=12}
_{Memory Allocs}	_{12,912,494 (± 0.02%)}	_{12,915,840 (± 0.05%)}	_~	_12,908,954	_12,946,635	_{p=0.478 n=12}
_{Config Time}	_{0.020s (± 1.59%)}	_{0.021s (± 1.18%)}	_~	_0.020s	_0.021s	_{p=0.089 n=12}
_{Parse Time}	_{0.328s (± 1.74%)}	_{0.324s (± 1.74%)}	_~	_0.306s	_0.339s	_{p=0.153 n=12}
_{Bind Time}	_{0.075s (± 4.59%)}	_{0.076s (± 8.50%)}	_~	_0.070s	_0.105s	_{p=0.156 n=12}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Emit Time}	_{1.865s (± 0.68%)}	_{1.890s (± 1.24%)}	_~	_1.855s	_1.965s	_{p=0.164 n=12}
_{Total Time}	_{2.304s (± 0.60%)}	_{2.326s (± 1.33%)}	_~	_2.283s	_2.441s	_{p=0.224 n=12}
_{mui-docs - native}
_Errors	_11,405	_11,405	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_4,339,337	_4,339,336	_{-1 (- 0.00%)}	_~	_~	_{p=0.000 n=12}
_Types	_1,379,387	_1,379,387	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{2,775,234k (± 0.06%)}	_{2,775,504k (± 0.07%)}	_~	_2,770,435k	_2,780,495k	_{p=0.977 n=12}
_{Memory Allocs}	_{32,731,873 (± 0.10%)}	_{32,730,517 (± 0.10%)}	_~	_32,666,178	_32,850,434	_{p=0.843 n=12}
_{Config Time}	_{0.020s (± 1.59%)}	_{0.021s (± 1.57%)}	_~	_0.020s	_0.021s	_{p=0.684 n=12}
_{Parse Time}	_{0.622s (± 1.82%)}	_{0.629s (± 2.44%)}	_~	_0.588s	_0.666s	_{p=0.541 n=12}
_{Bind Time}	_{0.003s (±12.54%)}	_{0.003s (±12.54%)}	_~	_0.002s	_0.003s	_{p=1.000 n=12}
_{Check Time}	_{10.634s (± 0.57%)}	_{10.549s (± 0.25%)}	_{-0.085s (- 0.80%)}	_10.496s	_10.632s	_{p=0.005 n=12}
_{Emit Time}	_{0.578s (±12.27%)}	_{0.595s (±12.32%)}	_~	_0.499s	_0.787s	_{p=0.853 n=12}
_{Total Time}	_{12.817s (± 0.45%)}	_{12.765s (± 0.49%)}	_~	_12.629s	_12.888s	_{p=0.272 n=12}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,388,669	_1,388,669	_~	_~	_~	_{p=1.000 n=12}
_Types	_441,862	_441,862	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{1,592,313k (± 0.63%)}	_{1,600,374k (± 0.48%)}	_~	_1,583,809k	_1,622,870k	_{p=0.101 n=12}
_{Memory Allocs}	_{82,407,529 (± 0.12%)}	_{82,434,608 (± 0.08%)}	_~	_82,201,204	_82,543,241	_{p=0.977 n=12}
_{Config Time}	_{0.004s (±16.32%)}	_{0.004s (±12.82%)}	_~	_0.003s	_0.006s	_{p=0.543 n=12}
_{Parse Time}	_{0.320s (± 2.43%)}	_{0.315s (± 2.16%)}	_~	_0.299s	_0.333s	_{p=0.325 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{2.166s (± 0.63%)}	_{2.153s (± 0.39%)}	_~	_2.132s	_2.180s	_{p=0.147 n=12}
_{Emit Time}	_{0.330s (± 2.36%)}	_{0.348s (± 5.63%)}	_~	_0.320s	_0.404s	_{p=0.086 n=12}
_{Total Time}	_{24.853s (± 0.54%)}	_{25.034s (± 0.85%)}	_~	_24.583s	_25.489s	_{p=0.242 n=12}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_334,953	_334,953	_~	_~	_~	_{p=1.000 n=12}
_Types	_197,616	_197,616	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{296,023k (± 0.02%)}	_{296,011k (± 0.03%)}	_~	_295,837k	_296,286k	_{p=0.932 n=12}
_{Memory Allocs}	_{4,621,807 (± 0.01%)}	_{4,621,414 (± 0.01%)}	_~	_4,619,623	_4,622,453	_{p=0.478 n=12}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.115s (± 3.29%)}	_{0.114s (± 4.76%)}	_~	_0.102s	_0.128s	_{p=0.541 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{1.040s (± 0.53%)}	_{1.045s (± 0.65%)}	_~	_1.030s	_1.065s	_{p=0.297 n=12}
_{Emit Time}	_{0.146s (± 5.55%)}	_{0.140s (± 5.92%)}	_~	_0.116s	_0.158s	_{p=0.298 n=12}
_{Total Time}	_{1.353s (± 0.89%)}	_{1.345s (± 1.27%)}	_~	_1.302s	_1.378s	_{p=0.541 n=12}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_303,834	_303,834	_~	_~	_~	_{p=1.000 n=12}
_Types	_181,663	_181,663	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{256,645k (± 0.02%)}	_{256,678k (± 0.02%)}	_~	_256,614k	_256,793k	_{p=0.514 n=12}
_{Memory Allocs}	_{1,614,169 (± 0.01%)}	_{1,613,973 (± 0.01%)}	_~	_1,613,685	_1,614,553	_{p=0.114 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.100s (± 3.45%)}	_{0.097s (± 5.28%)}	_~	_0.084s	_0.115s	_{p=0.172 n=12}
_{Bind Time}	_{0.039s (±10.61%)}	_{0.040s (±11.23%)}	_~	_0.030s	_0.052s	_{p=1.000 n=12}
_{Check Time}	_{0.819s (± 0.95%)}	_{0.812s (± 0.72%)}	_~	_0.800s	_0.830s	_{p=0.212 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{0.972s (± 0.93%)}	_{0.963s (± 0.87%)}	_~	_0.939s	_0.987s	_{p=0.368 n=12}
_{vscode - native}
_Errors	₃₉₆	₃₉₆	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_11,422,382	_11,422,232	_{-150 (- 0.00%)}	_~	_~	_{p=0.000 n=12}
_Types	_3,779,090	_3,779,038	_{-52 (- 0.00%)}	_~	_~	_{p=0.000 n=12}
_{Memory Used}	_{6,511,213k (± 0.03%)}	_{6,511,004k (± 0.01%)}	_~	_6,509,287k	_6,512,696k	_{p=0.443 n=12}
_{Memory Allocs}	_{56,068,584 (± 0.02%)}	_{56,062,104 (± 0.01%)}	_~	_56,052,460	_56,090,094	_{p=0.478 n=12}
_{Config Time}	_{0.075s (± 0.38%)}	_{0.075s (± 0.36%)}	_~	_0.074s	_0.076s	_{p=0.366 n=12}
_{Parse Time}	_{1.817s (± 3.12%)}	_{1.868s (± 3.82%)}	_~	_1.679s	_2.035s	_{p=0.242 n=12}
_{Bind Time}	_{0.633s (±18.86%)}	_{0.550s (±17.26%)}	_~	_0.444s	_0.900s	_{p=0.173 n=12}
_{Check Time}	_{14.133s (± 1.17%)}	_{14.262s (± 1.04%)}	_~	_13.848s	_14.552s	_{p=0.160 n=12}
_{Emit Time}	_{4.948s (±10.64%)}	_{4.725s (± 9.63%)}	_~	_4.071s	_5.932s	_{p=0.579 n=12}
_{Total Time}	_{21.693s (± 1.97%)}	_{21.564s (± 1.59%)}	_~	_20.929s	_22.548s	_{p=0.811 n=12}
_{webpack - native}
_Errors	₅₈₅	₅₈₅	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,325,855	_1,325,855	_~	_~	_~	_{p=1.000 n=12}
_Types	_627,988	_627,988	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{951,392k (± 0.01%)}	_{951,135k (± 0.02%)}	_{-257k (- 0.03%)}	_950,807k	_951,622k	_{p=0.024 n=12}
_{Memory Allocs}	_{6,739,043 (± 0.01%)}	_{6,740,626 (± 0.04%)}	_~	_6,735,439	_6,751,766	_{p=0.514 n=12}
_{Config Time}	_0.009s	_{0.009s (± 5.25%)}	_~	_0.009s	_0.011s	_{p=0.478 n=12}
_{Parse Time}	_{0.306s (± 3.72%)}	_{0.304s (± 4.31%)}	_~	_0.275s	_0.349s	_{p=0.681 n=12}
_{Bind Time}	_{0.092s (±19.62%)}	_{0.093s (±19.62%)}	_~	_0.066s	_0.138s	_{p=0.966 n=12}
_{Check Time}	_{1.937s (± 0.43%)}	_{1.956s (± 1.02%)}	_~	_1.919s	_2.027s	_{p=0.259 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{2.379s (± 0.56%)}	_{2.397s (± 0.95%)}	_~	_2.366s	_2.494s	_{p=0.370 n=12}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,062,854	_1,062,631	_{-223 (- 0.02%)}	_~	_~	_{p=0.000 n=12}
_Types	_390,845	_390,782	_{-63 (- 0.02%)}	_~	_~	_{p=0.000 n=12}
_{Memory Used}	_{548,055k (± 0.02%)}	_{547,952k (± 0.02%)}	_~	_547,749k	_548,255k	_{p=0.128 n=12}
_{Memory Allocs}	_{4,891,221 (± 0.08%)}	_{4,888,995 (± 0.07%)}	_~	_4,881,309	_4,897,166	_{p=0.443 n=12}
_{Config Time}	_0.002s	_0.002s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.115s (± 3.22%)}	_{0.114s (± 3.68%)}	_~	_0.104s	_0.126s	_{p=0.619 n=12}
_{Bind Time}	_{0.034s (±17.95%)}	_{0.033s (±17.58%)}	_~	_0.026s	_0.056s	_{p=0.751 n=12}
_{Check Time}	_{0.852s (± 1.11%)}	_{0.856s (± 0.86%)}	_~	_0.838s	_0.876s	_{p=0.385 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{1.010s (± 1.11%)}	_{1.012s (± 0.68%)}	_~	_0.995s	_1.024s	_{p=0.921 n=12}

System info unknown

Hosts

native

Scenarios

Compiler-Unions - native
angular-1 - native
mui-docs - native
strada-build-src - native
strada-compiler - native
ts-pre-modules - native
vscode - native
webpack - native
xstate-main - native

_Benchmark	_Name	_Iterations
_Current	_pr	₁₂
_Baseline	_baseline	₁₂

Developer Information:

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typescript-automation · 2026-10-13T23:22:20Z

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

Everything looks good!

typescript-automation · 2026-10-14T00:11:31Z

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

Everything looks good!

Mateusz Burzyński (Andarist) added 2 commits August 23, 2026 09:45

Port "Reuse cached resolved signatures early"

6705198

Prevent self-contextual return inference and restore diagnostics for …

2198dcc

…inapplicable reentrant calls.

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Mateusz Burzyński (Andarist) mentioned this pull request Aug 28, 2026

Matching Strada order of operations in recursive signature resolution #64014

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Fixed signature caching issue caused by reentrant signature checking - #64077

Fixed signature caching issue caused by reentrant signature checking#64077
Mateusz Burzyński (Andarist) wants to merge 3 commits into
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Andarist:fix-63949-reentrant-signature-cache

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