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Predicate inference fails for empty object and nullish values #58967
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Primitives are assignable to |
And because |
This issue has been marked as "Duplicate" and has seen no recent activity. It has been automatically closed for house-keeping purposes. |
🔎 Search Terms
"infer predicate object types", "infer predicate empty object", "infer predicate empty object null", "{} | null"
🕗 Version & Regression Information
⏯ Playground Link
https://www.typescriptlang.org/play/?ts=5.5.2#code/MYewdgzgLgBApgWwA5QJ4DkCuAbbMC8MA2gN4C+ANDGDtgLoB0AZgJbZRwBOAFBAQHwwAhEIgBKANwwA9NPgAPJHGAcAJjHJE6AKBh7ZMAHoB+baEixEKVAFUwquKzBx1hUpRiZ7jls9WNWdi5eAWFRSRk5OEVlNQ0yLV19ORMzcGgFJGwWYBYoLFwWCAALAmJyKhpcALYOHj58QT4hfEIq7AiDEABrJMijU3MMqzQsBAAjLjL3KgAGGqD60JFxKS7evX7UoctkNAAVTkwoYtRp8gW6kMaw1f7opRUXeMTNg2303esAMQBDbAgZzcF2YtWCDUE4TWURiT3UzgAblxXskBmkLNRwABRPYYWjnGBMEAgABc8RgHnal3Byyh-R6fXeg0+1FoRVKbnaVC8DicLmpSxuK06MMecURyJ0bxSpiAA
💻 Code
🙁 Actual behavior
Predicate inference fails for the cases where
{}
is declared along with a nullish value, using a predicate to test for truthiness or falsiness (!!x
/!x
). It infers a type that includes the nullishness.It also fails to infer the predicate for cases where array only contains nullish values.
It works if the object has at least one property, or using explicit bullishness check.
🙂 Expected behavior
The return type should reflect the truthiness of
{}
, as it is neither a nullish or falsy value and should pass the truthiness test.Additional information about the issue
The section "This is a gentle nudge away from truthiness footguns" in #57465 explains that object types should have no footguns:
That's why I expected the same for
{}
and the opposite with nullish-only values.The text was updated successfully, but these errors were encountered: