Skip declaration emit without a prior signature by jakebailey · Pull Request #4726 · microsoft/typescript-go

Jake Bailey (jakebailey) · 2026-07-24T03:02:19Z

WIP

Cover an incremental noEmit build where a change propagates through a re-export and its importer after source versions were stored as signatures.

When an unchanged importer has signature == version, there is no previous declaration signature available for comparison. Computing one may allow propagation to stop, but requires declaration emit. Skip that refinement and conservatively continue through the importer graph instead.

Copilot

Pull request overview

Optimizes incremental builds by avoiding unnecessary declaration-signature emission when no prior declaration signature exists.

Changes:

Conservatively propagates affected files without computing missing declaration signatures.
Adds re-export propagation coverage.
Updates incremental, no-emit, build, and watch baselines.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
`internal/execute/incremental/affectedfileshandler.go`	Skips unnecessary declaration-signature computation.
`internal/execute/tsctests/tsc_test.go`	Adds re-export propagation scenario.
`testdata/baselines/reference/tsc/incremental/incremental-signature-propagation-through-reexports.js`	Records the new scenario.
`testdata/baselines/reference/tsc/incremental/const-enums.js`	Updates const-enum incremental output.
`testdata/baselines/reference/tsc/incremental/const-enums-aliased.js`	Updates aliased const-enum output.
`testdata/baselines/reference/tsc/incremental/const-enums-aliased-in-different-file.js`	Updates cross-file alias output.
`testdata/baselines/reference/tsc/incremental/change-to-modifier-of-class-expression-field.js`	Updates class-expression incremental output.
`testdata/baselines/reference/tsc/noEmit/changes-incremental.js`	Updates no-emit incremental state.
`testdata/baselines/reference/tsc/noEmit/changes-with-initial-noEmit-incremental.js`	Updates initial no-emit state.
`testdata/baselines/reference/tsbuild/noEmit/changes-incremental.js`	Updates build-mode no-emit output.
`testdata/baselines/reference/tsbuild/noEmit/changes-with-initial-noEmit-incremental.js`	Updates initial build-mode no-emit output.
`testdata/baselines/reference/tscWatch/commandLineWatch/watch-handles-file-rapidly-recreated.js`	Removes redundant watch signature computation.
`testdata/baselines/reference/tscWatch/commandLineWatch/watch-detects-change-in-symlinked-node_modules-file.js`	Updates symlink watch signature behavior.

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Jake Bailey (jakebailey) · 2026-08-14T20:01:21Z

TypeScript Bot (@typescript-bot) perf test this

typescript-automation · 2026-08-14T20:01:25Z

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

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

typescript-automation · 2026-08-14T20:28:59Z

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	_115,480	_115,480	_~	_~	_~	_{p=1.000 n=12}
_Types	_96,945	_96,945	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{148,959k (± 0.61%)}	_{149,132k (± 0.38%)}	_~	_147,430k	_150,176k	_{p=0.799 n=12}
_{Memory Allocs}	_{2,247,461 (± 0.01%)}	_{2,247,499 (± 0.01%)}	_~	_2,247,224	_2,247,835	_{p=0.944 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.050s (± 3.32%)}	_{0.051s (± 2.96%)}	_~	_0.046s	_0.055s	_{p=0.636 n=12}
_{Bind Time}	_{0.014s (±10.34%)}	_{0.017s (±16.37%)}	_~	_0.012s	_0.024s	_{p=0.293 n=12}
_{Check Time}	_{0.616s (± 1.14%)}	_{0.619s (± 0.89%)}	_~	_0.608s	_0.633s	_{p=0.235 n=12}
_{Emit Time}	_{0.323s (± 1.70%)}	_{0.330s (± 2.81%)}	_~	_0.309s	_0.366s	_{p=0.370 n=12}
_{Total Time}	_{1.011s (± 0.82%)}	_{1.024s (± 1.16%)}	_{+0.013s (+ 1.26%)}	_1.001s	_1.079s	_{p=0.040 n=12}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_{847,355 (± 0.06%)}	_{846,832 (± 0.11%)}	_~	_844,947	_848,469	_{p=0.514 n=12}
_Types	_{249,912 (± 0.00%)}	_{249,913 (± 0.00%)}	_~	_249,910	_249,922	_{p=0.768 n=12}
_{Memory Used}	_{793,551k (± 0.08%)}	_{793,034k (± 0.07%)}	_~	_791,823k	_795,026k	_{p=0.178 n=12}
_{Memory Allocs}	_{13,044,731 (± 0.10%)}	_{13,034,685 (± 0.01%)}	_~	_13,031,182	_13,041,216	_{p=0.713 n=12}
_{Config Time}	_{0.020s (± 0.91%)}	_{0.020s (± 0.91%)}	_~	_0.019s	_0.020s	_{p=1.000 n=12}
_{Parse Time}	_{0.352s (± 1.84%)}	_{0.348s (± 2.03%)}	_~	_0.332s	_0.365s	_{p=0.272 n=12}
_{Bind Time}	_{0.075s (± 5.34%)}	_{0.084s (±17.11%)}	_~	_0.073s	_0.145s	_{p=0.460 n=12}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Emit Time}	_{1.983s (± 0.69%)}	_{1.996s (± 1.32%)}	_~	_1.951s	_2.096s	_{p=0.745 n=12}
_{Total Time}	_{2.450s (± 0.80%)}	_{2.468s (± 1.56%)}	_~	_2.398s	_2.596s	_{p=0.876 n=12}
_{mui-docs - native}
_Errors	_{11,279 (± 0.02%)}	_{11,278 (± 0.02%)}	_~	_11,268	_11,282	_{p=0.633 n=12}
_Symbols	_4,230,792	_4,230,792	_~	_~	_~	_{p=1.000 n=12}
_Types	_1,591,020	_1,591,020	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{4,852,380k (± 0.03%)}	_{4,851,890k (± 0.03%)}	_~	_4,848,448k	_4,856,976k	_{p=0.671 n=12}
_{Memory Allocs}	_{48,396,628 (± 0.04%)}	_{48,399,697 (± 0.03%)}	_~	_48,361,766	_48,441,930	_{p=0.671 n=12}
_{Config Time}	_0.019s	_0.019s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.672s (± 2.15%)}	_{0.675s (± 1.14%)}	_~	_0.649s	_0.692s	_{p=0.988 n=12}
_{Bind Time}	_{0.002s (±13.27%)}	_{0.003s (±11.61%)}	_~	_0.002s	_0.003s	_{p=0.220 n=12}
_{Check Time}	_{18.791s (± 0.79%)}	_{18.732s (± 0.65%)}	_~	_18.340s	_19.063s	_{p=0.291 n=12}
_{Emit Time}	_{0.521s (± 0.27%)}	_{0.520s (± 0.32%)}	_~	_0.517s	_0.525s	_{p=0.311 n=12}
_{Total Time}	_{20.934s (± 0.78%)}	_{20.870s (± 0.71%)}	_~	_20.375s	_21.218s	_{p=0.291 n=12}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,394,411	_1,394,411	_~	_~	_~	_{p=1.000 n=12}
_Types	_443,627	_443,627	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{1,642,250k (± 0.23%)}	_{1,642,450k (± 0.24%)}	_~	_1,632,887k	_1,652,627k	_{p=0.887 n=12}
_{Memory Allocs}	_{96,906,331 (± 0.03%)}	_{96,915,204 (± 0.04%)}	_~	_96,830,685	_97,005,306	_{p=0.843 n=12}
_{Config Time}	_{0.005s (±10.49%)}	_{0.005s (±10.86%)}	_~	_0.004s	_0.006s	_{p=0.800 n=12}
_{Parse Time}	_{0.236s (± 2.58%)}	_{0.243s (± 3.26%)}	_~	_0.226s	_0.263s	_{p=0.202 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{2.195s (± 0.32%)}	_{2.199s (± 0.38%)}	_~	_2.179s	_2.219s	_{p=0.713 n=12}
_{Emit Time}	_{0.360s (± 3.33%)}	_{0.358s (± 4.28%)}	_~	_0.304s	_0.384s	_{p=1.000 n=12}
_{Total Time}	_{30.567s (± 0.46%)}	_{30.542s (± 0.66%)}	_~	_30.041s	_30.967s	_{p=0.977 n=12}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_337,618	_337,618	_~	_~	_~	_{p=1.000 n=12}
_Types	_198,941	_198,941	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{319,649k (± 0.03%)}	_{319,633k (± 0.04%)}	_~	_319,339k	_319,909k	_{p=0.887 n=12}
_{Memory Allocs}	_{4,660,967 (± 0.01%)}	_{4,660,769 (± 0.01%)}	_~	_4,659,563	_4,661,847	_{p=0.799 n=12}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.115s (± 4.91%)}	_{0.115s (± 5.15%)}	_~	_0.098s	_0.130s	_{p=0.599 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{1.061s (± 0.60%)}	_{1.057s (± 0.71%)}	_~	_1.042s	_1.078s	_{p=0.340 n=12}
_{Emit Time}	_{0.148s (±10.00%)}	_{0.154s (±10.79%)}	_~	_0.114s	_0.179s	_{p=0.401 n=12}
_{Total Time}	_{1.379s (± 0.73%)}	_{1.385s (± 0.95%)}	_~	_1.354s	_1.410s	_{p=0.339 n=12}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_305,341	_305,341	_~	_~	_~	_{p=1.000 n=12}
_Types	_182,038	_182,038	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{277,323k (± 0.01%)}	_{277,293k (± 0.02%)}	_~	_277,140k	_277,475k	_{p=0.284 n=12}
_{Memory Allocs}	_{1,628,098 (± 0.01%)}	_{1,628,082 (± 0.01%)}	_~	_1,627,619	_1,628,521	_{p=0.671 n=12}
_{Config Time}	_{0.000s (±217.90%)}	_{0.000s (±113.79%)}	_~	_0.000s	_0.001s	_{p=0.590 n=12}
_{Parse Time}	_{0.100s (± 4.18%)}	_{0.099s (± 3.57%)}	_~	_0.089s	_0.110s	_{p=0.701 n=12}
_{Bind Time}	_{0.038s (±12.08%)}	_{0.036s (±10.96%)}	_~	_0.029s	_0.048s	_{p=0.659 n=12}
_{Check Time}	_{0.844s (± 0.66%)}	_{0.845s (± 0.86%)}	_~	_0.826s	_0.861s	_{p=0.898 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{0.997s (± 0.67%)}	_{0.994s (± 0.66%)}	_~	_0.980s	_1.012s	_{p=0.702 n=12}
_{vscode - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_7,731,630	_7,731,630	_~	_~	_~	_{p=1.000 n=12}
_Types	_2,662,693	_2,662,693	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{5,226,807k (± 0.02%)}	_{5,225,541k (± 0.01%)}	_{-1,265k (- 0.02%)}	_5,223,461k	_5,227,417k	_{p=0.024 n=12}
_{Memory Allocs}	_{40,503,490 (± 0.03%)}	_{40,498,493 (± 0.04%)}	_~	_40,486,163	_40,566,470	_{p=0.198 n=12}
_{Config Time}	_{0.061s (± 0.53%)}	_{0.061s (± 0.53%)}	_~	_0.060s	_0.062s	_{p=0.246 n=12}
_{Parse Time}	_{1.614s (± 1.39%)}	_{1.594s (± 2.26%)}	_~	_1.476s	_1.654s	_{p=0.452 n=12}
_{Bind Time}	_{0.333s (± 0.34%)}	_{0.352s (±14.28%)}	_~	_0.301s	_0.604s	_{p=0.500 n=12}
_{Check Time}	_{9.829s (± 0.42%)}	_{9.787s (± 1.04%)}	_~	_9.330s	_9.887s	_{p=0.660 n=12}
_{Emit Time}	_{2.935s (± 0.89%)}	_{3.056s (± 8.39%)}	_~	_2.870s	_4.292s	_{p=0.370 n=12}
_{Total Time}	_{14.850s (± 0.16%)}	_{14.929s (± 1.27%)}	_~	_14.723s	_15.867s	_{p=0.990 n=12}
_{webpack - native}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,380	_1,380	_~	_~	_~	_{p=1.000 n=12}
_Types	₃₄₀	₃₄₀	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{194,474k (± 0.08%)}	_{194,421k (± 0.05%)}	_~	_194,225k	_194,776k	_{p=0.478 n=12}
_{Memory Allocs}	_{822,664 (± 0.10%)}	_{824,369 (± 0.49%)}	_~	_820,243	_840,807	_{p=0.410 n=12}
_{Config Time}	_0.006s	_0.006s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.160s (± 2.68%)}	_{0.160s (± 2.78%)}	_~	_0.148s	_0.171s	_{p=0.809 n=12}
_{Bind Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{0.167s (± 2.55%)}	_{0.166s (± 2.66%)}	_~	_0.155s	_0.178s	_{p=0.767 n=12}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,020,005	_1,020,005	_~	_~	_~	_{p=1.000 n=12}
_Types	_376,891	_376,891	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{603,462k (± 0.01%)}	_{603,399k (± 0.01%)}	_~	_603,204k	_603,620k	_{p=0.193 n=12}
_{Memory Allocs}	_{4,748,651 (± 0.03%)}	_{4,748,970 (± 0.02%)}	_~	_4,746,991	_4,752,313	_{p=0.977 n=12}
_{Config Time}	_0.003s	_{0.003s (± 8.64%)}	_~	_0.002s	_0.003s	_{p=0.478 n=12}
_{Parse Time}	_{0.146s (± 3.23%)}	_{0.144s (± 3.38%)}	_~	_0.136s	_0.163s	_{p=0.744 n=12}
_{Bind Time}	_{0.040s (±11.83%)}	_{0.047s (±16.49%)}	_~	_0.034s	_0.073s	_{p=0.136 n=12}
_{Check Time}	_{1.085s (± 0.91%)}	_{1.101s (± 0.77%)}	_{+0.016s (+ 1.46%)}	_1.087s	_1.128s	_{p=0.032 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{1.285s (± 1.32%)}	_{1.306s (± 0.78%)}	_~	_1.275s	_1.330s	_{p=0.060 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

lsp

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-UnionsLSP - native}
_{Req 1 - updateOpen}	_{13ms (±10.85%)}	_{14ms (±12.31%)}	_~	_12ms	_19ms	_{p=0.985 n=12}
_{Req 2 - geterr}	_{580ms (± 0.35%)}	_{577ms (± 0.51%)}	_~	_568ms	_585ms	_{p=0.242 n=12}
_{Req 3 - references}	_{43ms (± 2.74%)}	_{45ms (± 5.10%)}	_{🔻+3ms (+ 6.04%)}	_39ms	_51ms	_{p=0.040 n=12}
_{Req 4 - navto}	_{17ms (± 1.90%)}	_{17ms (± 1.58%)}	_~	_16ms	_18ms	_{p=0.832 n=12}
_{Req 5 - completionInfo count}	_1,363	_1,363	_~	_~	_~	_{p=1.000 n=12}
_{Req 5 - completionInfo}	_{18ms (± 4.81%)}	_{17ms (± 7.63%)}	_~	_14ms	_19ms	_{p=0.923 n=12}
_{CompilerLSP - native}
_{Req 1 - updateOpen}	_{13ms (± 4.41%)}	_{13ms (± 7.03%)}	_~	_12ms	_16ms	_{p=1.000 n=12}
_{Req 2 - geterr}	_{298ms (± 0.59%)}	_{299ms (± 0.45%)}	_~	_294ms	_302ms	_{p=0.381 n=12}
_{Req 3 - references}	_{53ms (± 2.68%)}	_{51ms (± 4.41%)}	_~	_46ms	_56ms	_{p=0.491 n=12}
_{Req 4 - navto}	_{17ms (± 3.57%)}	_{17ms (± 3.77%)}	_~	_16ms	_20ms	_{p=0.684 n=12}
_{Req 5 - completionInfo count}	_1,525	_1,525	_~	_~	_~	_{p=1.000 n=12}
_{Req 5 - completionInfo}	_{16ms (± 5.77%)}	_{17ms (± 5.80%)}	_~	_15ms	_19ms	_{p=0.641 n=12}

System info unknown

Hosts

native

Scenarios

CompilerLSP - native
Compiler-UnionsLSP - native
xstate-main-1-LSP - native

_Benchmark	_Name	_Iterations
_Current	_pr	₁₂
_Baseline	_baseline	₁₂

startup

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{lsp-startup - native}
_{Execution time}	_{4.80ms (±365.10%)}	_{4.80ms (±365.10%)}	_~	_0.00ms	_481.93ms	_{p=0.856 n=1200}
_{tsgo-startup - native}
_{Execution time}	_{5.86ms (±365.10%)}	_{5.90ms (±365.11%)}	_{+0.04ms (+ 0.60%)}	_0.00ms	_605.09ms	_{p=0.000 n=1200}

System info unknown

Hosts

native

Scenarios

lsp-startup - native
tsgo-startup - native

_Benchmark	_Name	_Iterations
_Current	_pr	₁₂
_Baseline	_baseline	₁₂

Developer Information:

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Jake Bailey (jakebailey) added 2 commits July 23, 2026 19:59

Add test for propagation without declaration signatures

a246722

Cover an incremental noEmit build where a change propagates through a re-export and its importer after source versions were stored as signatures.

Jake Bailey (jakebailey) requested a balanced review from Copilot August 14, 2026 18:29

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Skip declaration emit without a prior signature - #4726

Skip declaration emit without a prior signature#4726
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