Don’t allow an object literal with a spread as a fallback for destructuring a property not present in all constituents #43783
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…turing a property not present in all constituents
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Heya @andrewbranch, I've started to run the parallelized community code test suite on this PR at 2950db9. You can monitor the build here. |
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sandersn
approved these changes
Apr 23, 2021
RyanCavanaugh
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Apr 23, 2021
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Fixes #43174
#31711 allowed object literals as fallbacks for destructuring, such that
const { x } = foo || {}was allowed even though{}has no propertyx. The only criteria for an object constituent of a union to be considered to have{ [key: string]: undefined }index signature was that it be an object literal—the common pattern seems to be an empty object literal, but any object literal ought to avoid excess property pitfalls through aliasing.... except, that logic neglected spreads, which could introduce arbitrary extra properties of arbitrary types, as demonstrated in #43174.