Reject exports from global augmentations by Copilot · Pull Request #64162 · microsoft/TypeScript

Copilot · 2026-09-04T00:33:41Z

Description

export { XYZ } incorrectly accepted bindings declared in a declare global augmentation.

Changes

Treat global-augmentation module blocks as non-local export sources.
Add regression coverage for:

declare global {
    var XYZ: number;
}

export { XYZ }; // TS2661

Fixes No error when exporting from global augmentations #64152

Co-authored-by: DanielRosenwasser <972891+DanielRosenwasser@users.noreply.github.com>

Copilot

🟢 Approval recommended

The focused checker fix has regression coverage and no unresolved issues.

Pull request overview

Rejects exports whose bindings originate from declare global augmentations, fixing #64152.

Changes:

Detect global-augmentation declarations during export validation.
Add regression coverage and compiler baselines for TS2661.

File summaries

File	Description
`tsc/testdata/tests/cases/compiler/exportSpecifierForAGlobalAugmentation.ts`	Adds the regression case.
`tsc/testdata/baselines/reference/compiler/exportSpecifierForAGlobalAugmentation.types`	Records inferred types.
`tsc/testdata/baselines/reference/compiler/exportSpecifierForAGlobalAugmentation.symbols`	Records symbol resolution.
`tsc/testdata/baselines/reference/compiler/exportSpecifierForAGlobalAugmentation.js`	Records emitted output.
`tsc/testdata/baselines/reference/compiler/exportSpecifierForAGlobalAugmentation.errors.txt`	Verifies the TS2661 diagnostic.
`tsc/internal/checker/checker.go`	Rejects exports sourced from global augmentations.

Review details

Files reviewed: 6/6 changed files
Comments generated: 0
Review effort level: Balanced

💡 Add a code-review agent skill for context-aware, tailored reviews. Learn more in the docs.

Daniel Rosenwasser (DanielRosenwasser) · 2026-09-05T00:47:17Z

TypeScript Bot (@typescript-bot) test it

typescript-automation · 2026-09-05T00:47:23Z

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 · 2026-09-05T01:13:59Z

Daniel Rosenwasser (@DanielRosenwasser) Here are the results of running the user tests with tsc comparing main and refs/pull/64162/merge:

There were infrastructure failures potentially unrelated to your change:

2 instances of "Package install failed"
1 instance of "Git clone failed"

Otherwise...

Something interesting changed - please have a look.

Details

xterm.js

src/tsconfig-library-base.json

[NEW] error TS2661: Cannot export 'AllowSharedBuffer'. Only local declarations can be exported from a module.
- file:///mnt/ts_downloads/_/m/xterm.js/node_modules/@types/node/buffer.d.ts#L128 in src/tsconfig-library-base.json
[NEW] error TS2661: Cannot export 'Buffer'. Only local declarations can be exported from a module.
- file:///mnt/ts_downloads/_/m/xterm.js/node_modules/@types/node/buffer.d.ts#L128 in src/tsconfig-library-base.json
[NEW] error TS2661: Cannot export 'NonSharedBuffer'. Only local declarations can be exported from a module.
- file:///mnt/ts_downloads/_/m/xterm.js/node_modules/@types/node/buffer.d.ts#L128 in src/tsconfig-library-base.json
[NEW] error TS2661: Cannot export 'BufferEncoding'. Only local declarations can be exported from a module.
- file:///mnt/ts_downloads/_/m/xterm.js/node_modules/@types/node/buffer.d.ts#L244 in src/tsconfig-library-base.json

typescript-automation · 2026-09-05T01:15:19Z

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 - 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}	_{148,013k (± 0.49%)}	_{148,350k (± 0.58%)}	_~	_146,499k	_150,733k	_{p=0.630 n=12}
_{Memory Allocs}	_{2,271,134 (± 0.00%)}	_{2,271,232 (± 0.00%)}	_~	_2,270,976	_2,271,604	_{p=0.089 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.041s (± 4.67%)}	_{0.041s (± 4.22%)}	_~	_0.036s	_0.045s	_{p=0.924 n=12}
_{Bind Time}	_{0.013s (±10.12%)}	_{0.013s (±12.04%)}	_~	_0.010s	_0.017s	_{p=0.763 n=12}
_{Check Time}	_{0.499s (± 1.10%)}	_{0.496s (± 0.98%)}	_~	_0.486s	_0.506s	_{p=0.399 n=12}
_{Emit Time}	_{0.274s (± 2.56%)}	_{0.270s (± 1.57%)}	_~	_0.260s	_0.287s	_{p=0.399 n=12}
_{Total Time}	_{0.833s (± 1.31%)}	_{0.826s (± 0.70%)}	_~	_0.813s	_0.848s	_{p=0.560 n=12}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_{846,839 (± 0.09%)}	_{847,257 (± 0.05%)}	_~	_846,210	_848,254	_{p=0.347 n=12}
_Types	_{249,852 (± 0.00%)}	_{249,853 (± 0.00%)}	_~	_249,849	_249,864	_{p=0.563 n=12}
_{Memory Used}	_{793,229k (± 0.06%)}	_{793,223k (± 0.05%)}	_~	_792,034k	_793,942k	_{p=0.660 n=12}
_{Memory Allocs}	_{12,955,907 (± 0.05%)}	_{12,957,281 (± 0.09%)}	_~	_12,948,457	_13,009,231	_{p=0.514 n=12}
_{Config Time}	_0.016s	_0.016s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.273s (± 1.79%)}	_{0.271s (± 2.48%)}	_~	_0.253s	_0.284s	_{p=0.660 n=12}
_{Bind Time}	_{0.064s (±11.62%)}	_{0.067s (±13.66%)}	_~	_0.057s	_0.094s	_{p=0.932 n=12}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Emit Time}	_{1.630s (± 1.12%)}	_{1.641s (± 1.52%)}	_~	_1.599s	_1.727s	_{p=0.876 n=12}
_{Total Time}	_{2.001s (± 1.30%)}	_{2.013s (± 1.54%)}	_~	_1.971s	_2.119s	_{p=0.522 n=12}
_{mui-docs - native}
_Errors	_{11,275 (± 0.05%)}	_{11,274 (± 0.06%)}	_~	_11,243	_11,281	_{p=0.852 n=12}
_Symbols	_4,165,469	_4,165,469	_~	_~	_~	_{p=1.000 n=12}
_Types	_1,592,109	_1,592,109	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{4,689,405k (± 0.03%)}	_{4,688,146k (± 0.04%)}	_~	_4,683,757k	_4,693,987k	_{p=0.242 n=12}
_{Memory Allocs}	_{47,010,599 (± 0.04%)}	_{47,011,095 (± 0.04%)}	_~	_46,957,795	_47,067,081	_{p=0.932 n=12}
_{Config Time}	_{0.016s (± 1.98%)}	_{0.016s (± 1.98%)}	_~	_0.015s	_0.016s	_{p=1.000 n=12}
_{Parse Time}	_{0.546s (± 1.71%)}	_{0.546s (± 2.35%)}	_~	_0.503s	_0.573s	_{p=0.966 n=12}
_{Bind Time}	_0.002s	_{0.002s (± 8.72%)}	_~	_0.002s	_0.003s	_{p=1.000 n=12}
_{Check Time}	_{17.303s (± 0.64%)}	_{17.175s (± 0.33%)}	_~	_17.098s	_17.366s	_{p=0.068 n=12}
_{Emit Time}	_{0.442s (± 4.92%)}	_{0.433s (± 0.38%)}	_~	_0.430s	_0.438s	_{p=0.593 n=12}
_{Total Time}	_{19.058s (± 0.66%)}	_{18.898s (± 0.39%)}	_~	_18.773s	_19.096s	_{p=0.052 n=12}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,394,252	_1,394,252	_~	_~	_~	_{p=1.000 n=12}
_Types	_443,418	_443,418	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{1,646,202k (± 0.26%)}	_{1,647,292k (± 0.35%)}	_~	_1,632,283k	_1,664,468k	_{p=0.713 n=12}
_{Memory Allocs}	_{97,031,113 (± 0.03%)}	_{97,058,514 (± 0.05%)}	_~	_96,960,855	_97,195,879	_{p=0.514 n=12}
_{Config Time}	_{0.004s (±10.30%)}	_{0.004s (±13.70%)}	_~	_0.003s	_0.005s	_{p=0.384 n=12}
_{Parse Time}	_{0.194s (± 2.27%)}	_{0.196s (± 2.13%)}	_~	_0.184s	_0.209s	_{p=0.619 n=12}
_{Bind Time}	_0.000s	_{0.000s (±217.90%)}	_~	_0.000s	_0.003s	_{p=1.000 n=12}
_{Check Time}	_{1.822s (± 0.41%)}	_{1.803s (± 0.45%)}	_{-0.019s (- 1.03%)}	_1.781s	_1.823s	_{p=0.002 n=12}
_{Emit Time}	_{0.277s (± 6.59%)}	_{0.279s (± 6.23%)}	_~	_0.243s	_0.323s	_{p=0.943 n=12}
_{Total Time}	_{24.835s (± 0.85%)}	_{24.739s (± 0.66%)}	_~	_24.411s	_25.246s	_{p=0.524 n=12}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_337,531	_337,531	_~	_~	_~	_{p=1.000 n=12}
_Types	_198,830	_198,830	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{319,417k (± 0.03%)}	_{319,563k (± 0.02%)}	_{+146k (+ 0.05%)}	_319,427k	_319,721k	_{p=0.024 n=12}
_{Memory Allocs}	_{4,672,622 (± 0.01%)}	_{4,673,075 (± 0.01%)}	_~	_4,671,871	_4,674,616	_{p=0.143 n=12}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.115s (± 4.09%)}	_{0.114s (± 4.59%)}	_~	_0.101s	_0.128s	_{p=0.722 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{1.051s (± 0.37%)}	_{1.047s (± 0.56%)}	_~	_1.030s	_1.063s	_{p=0.212 n=12}
_{Emit Time}	_{0.127s (±10.69%)}	_{0.143s (±10.64%)}	_~	_0.101s	_0.171s	_{p=0.110 n=12}
_{Total Time}	_{1.350s (± 0.70%)}	_{1.358s (± 0.90%)}	_~	_1.318s	_1.378s	_{p=0.147 n=12}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_305,179	_305,179	_~	_~	_~	_{p=1.000 n=12}
_Types	_181,876	_181,876	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{277,174k (± 0.02%)}	_{277,136k (± 0.02%)}	_~	_277,020k	_277,224k	_{p=0.478 n=12}
_{Memory Allocs}	_{1,641,835 (± 0.01%)}	_{1,641,809 (± 0.01%)}	_~	_1,641,420	_1,642,276	_{p=0.630 n=12}
_{Config Time}	_{0.000s (±92.91%)}	_{0.000s (±146.91%)}	_~	_0.000s	_0.001s	_{p=0.640 n=12}
_{Parse Time}	_{0.099s (± 4.99%)}	_{0.100s (± 4.79%)}	_~	_0.088s	_0.113s	_{p=0.619 n=12}
_{Bind Time}	_{0.040s (±10.41%)}	_{0.036s (± 7.69%)}	_~	_0.031s	_0.046s	_{p=0.145 n=12}
_{Check Time}	_{0.838s (± 0.43%)}	_{0.837s (± 0.66%)}	_~	_0.824s	_0.855s	_{p=0.680 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{0.991s (± 0.83%)}	_{0.988s (± 0.74%)}	_~	_0.972s	_1.009s	_{p=0.788 n=12}
_{vscode - native}
_Errors	₃₄₉	₃₄₉	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_8,291,678	_8,291,678	_~	_~	_~	_{p=1.000 n=12}
_Types	_2,834,636	_2,834,636	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{5,611,675k (± 0.02%)}	_{5,613,039k (± 0.02%)}	_{+1,364k (+ 0.02%)}	_5,611,309k	_5,616,142k	_{p=0.039 n=12}
_{Memory Allocs}	_{43,156,251 (± 0.01%)}	_{43,162,556 (± 0.03%)}	_~	_43,150,800	_43,216,255	_{p=0.347 n=12}
_{Config Time}	_{0.063s (± 0.51%)}	_{0.064s (± 1.38%)}	_~	_0.063s	_0.068s	_{p=0.733 n=12}
_{Parse Time}	_{1.627s (± 3.80%)}	_{1.668s (± 2.97%)}	_~	_1.531s	_1.766s	_{p=0.272 n=12}
_{Bind Time}	_{0.479s (±22.14%)}	_{0.389s (±15.05%)}	_~	_0.349s	_0.671s	_{p=0.283 n=12}
_{Check Time}	_{9.873s (± 1.77%)}	_{10.013s (± 1.30%)}	_~	_9.563s	_10.230s	_{p=0.203 n=12}
_{Emit Time}	_{3.994s (±13.60%)}	_{3.549s (±10.77%)}	_~	_3.161s	_5.020s	_{p=0.291 n=12}
_{Total Time}	_{16.133s (± 2.60%)}	_{15.776s (± 1.83%)}	_~	_15.439s	_16.960s	_{p=0.319 n=12}
_{webpack - native}
_Errors	₅₄₅	₅₄₉	_{+4 (+ 0.73%)}	_~	_~	_{p=0.000 n=12}
_Symbols	_918,784	_918,784	_~	_~	_~	_{p=1.000 n=12}
_Types	_421,470	_421,470	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{705,473k (± 0.02%)}	_{705,437k (± 0.02%)}	_~	_705,140k	_705,913k	_{p=0.443 n=12}
_{Memory Allocs}	_{4,581,617 (± 0.02%)}	_{4,581,899 (± 0.02%)}	_~	_4,580,882	_4,585,570	_{p=0.242 n=12}
_{Config Time}	_0.008s	_0.008s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.222s (± 2.76%)}	_{0.226s (± 1.69%)}	_~	_0.213s	_0.235s	_{p=0.182 n=12}
_{Bind Time}	_{0.048s (±11.67%)}	_{0.046s (± 5.44%)}	_~	_0.043s	_0.055s	_{p=0.721 n=12}
_{Check Time}	_{1.280s (± 0.47%)}	_{1.285s (± 0.95%)}	_~	_1.254s	_1.335s	_{p=0.486 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{1.582s (± 0.51%)}	_{1.589s (± 0.79%)}	_~	_1.564s	_1.640s	_{p=0.434 n=12}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,022,532	_1,022,532	_~	_~	_~	_{p=1.000 n=12}
_Types	_376,962	_376,962	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{603,535k (± 0.01%)}	_{603,504k (± 0.02%)}	_~	_603,240k	_603,759k	_{p=0.478 n=12}
_{Memory Allocs}	_{4,753,438 (± 0.05%)}	_{4,753,895 (± 0.04%)}	_~	_4,750,242	_4,760,619	_{p=0.590 n=12}
_{Config Time}	_{0.003s (± 8.64%)}	_{0.003s (±10.34%)}	_~	_0.002s	_0.003s	_{p=1.000 n=12}
_{Parse Time}	_{0.145s (± 2.99%)}	_{0.147s (± 3.06%)}	_~	_0.137s	_0.157s	_{p=0.679 n=12}
_{Bind Time}	_{0.046s (±15.71%)}	_{0.043s (±18.74%)}	_~	_0.032s	_0.067s	_{p=0.830 n=12}
_{Check Time}	_{1.036s (± 0.53%)}	_{1.045s (± 1.02%)}	_~	_1.026s	_1.069s	_{p=0.203 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{1.243s (± 0.99%)}	_{1.249s (± 1.04%)}	_~	_1.222s	_1.287s	_{p=0.401 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:

Download Benchmarks

typescript-automation · 2026-09-05T01:27:01Z

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

Everything looks the same!

You can check the log here.

typescript-automation · 2026-09-05T01:47:14Z

Daniel Rosenwasser (@DanielRosenwasser) Here are the results of running the top 400 repos with tsc comparing main and refs/pull/64162/merge:

Everything looks good!

Jake Bailey (jakebailey) · 2026-09-05T01:53:59Z

DT is not yet working, I suspect this will break a lot there

Initial plan

269b0cc

Copilot AI assigned Copilot and Daniel Rosenwasser (DanielRosenwasser) Sep 4, 2026

typescript-automation Bot added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Sep 4, 2026

Copilot started work on behalf of Daniel Rosenwasser (DanielRosenwasser) September 4, 2026 00:34 View session

Copilot AI linked an issue Sep 4, 2026 that may be closed by this pull request

No error when exporting from global augmentations #64152

Open

Copilot AI and others added 2 commits September 4, 2026 00:55

Reject exports from global augmentations

67aea51

Co-authored-by: DanielRosenwasser <972891+DanielRosenwasser@users.noreply.github.com>

Simplify global export validation

d6c2b0f

Co-authored-by: DanielRosenwasser <972891+DanielRosenwasser@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Fix issue with exporting from global augmentations~~ Reject exports from global augmentations Sep 4, 2026

Copilot finished work on behalf of Daniel Rosenwasser (DanielRosenwasser) September 4, 2026 01:07

Copilot AI requested a review from Daniel Rosenwasser (DanielRosenwasser) September 4, 2026 01:07

Jake Bailey (jakebailey) requested a balanced review from Copilot September 4, 2026 17:42

Copilot started reviewing on behalf of Jake Bailey (jakebailey) September 4, 2026 17:43 View session

Copilot AI reviewed Sep 4, 2026

View reviewed changes

Navigation Menu

Uh oh!

Reject exports from global augmentations - #64162

Reject exports from global augmentations#64162
Daniel Rosenwasser (DanielRosenwasser) with Copilot wants to merge 3 commits into
mainfrom
copilot/fix-global-augmentation-export

Copilot AI commented Sep 4, 2026 •

edited

Loading

Uh oh!

Copilot AI left a comment

Uh oh!

Daniel Rosenwasser (DanielRosenwasser) commented Sep 5, 2026

Uh oh!

typescript-automation Bot commented Sep 5, 2026 •

edited

Loading

Uh oh!

typescript-automation Bot commented Sep 5, 2026

xterm.js

src/tsconfig-library-base.json

Uh oh!

typescript-automation Bot commented Sep 5, 2026

tsc

Uh oh!

typescript-automation Bot commented Sep 5, 2026

Uh oh!

typescript-automation Bot commented Sep 5, 2026

Uh oh!

Jake Bailey (jakebailey) commented Sep 5, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

Uh oh!

Conversation

Copilot AI commented Sep 4, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Description

Changes

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

🟢 Approval recommended

Uh oh!

Daniel Rosenwasser (DanielRosenwasser) commented Sep 5, 2026

Uh oh!

typescript-automation Bot commented Sep 5, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

typescript-automation Bot commented Sep 5, 2026

xterm.js

src/tsconfig-library-base.json

Uh oh!

typescript-automation Bot commented Sep 5, 2026

tsc

Uh oh!

typescript-automation Bot commented Sep 5, 2026

Uh oh!

typescript-automation Bot commented Sep 5, 2026

Uh oh!

Jake Bailey (jakebailey) commented Sep 5, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

Copilot AI commented Sep 4, 2026 •

edited

Loading

typescript-automation Bot commented Sep 5, 2026 •

edited

Loading