fix Promise.prototype.finally to correctly propagate onFinally errors - #1725
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Perryvw merged 2 commits intoMay 31, 2026
Merged
fix Promise.prototype.finally to correctly propagate onFinally errors#1725Perryvw merged 2 commits into
Perryvw merged 2 commits into
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Pull request overview
Note
Copilot was unable to run its full agentic suite in this review.
Fixes Promise.finally to conform to the ES spec: when the onFinally callback throws or returns a rejected promise, the resulting error now overrides the original fulfillment value or rejection reason. Also handles non-function arguments by delegating to .then.
Changes:
- Reimplement Promise.prototype.finally to wrap the onFinally invocation in a new promise so its rejection propagates.
- Add unit tests for Promise.finally covering throws and rejected-promise returns over both fulfilled and rejected chains.
- Add async/await tests covering re-throwing in catch and overriding behavior of finally (throw and return).
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/lualib/Promise.ts | Rewrites finally to use the TC39 polyfill pattern so onFinally errors override the original outcome. |
| test/unit/builtins/promise.spec.ts | Adds tests verifying that throws / rejected returns from finally override prior value or reason. |
| test/unit/builtins/async-await.spec.ts | Adds async/await tests exercising re-throws and finally overriding catch results. |
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Summary