facebook/flow v0.221.0

on GitHub

Likely to cause new Flow errors:

• Changed the signature of React.Fragment to only accept children and the key prop.
• Changed the signature of React.useRef to return an opaque type.
• Fixed a case where, in some cases, contextually-typed callbacks being passed as props would be typed as any rather than producing underconstrained-implicit-instantiation errors. This will result in new underconstrained errors, but removes a source of untracked unsoundness.
• Banned non-tuple arrays from being spread into tuple types. It previously resulted in any without error.

Notable bug fixes:

• Improved signature help support for optional chaining calls and intersection types. Now we will show all possible signature possibilities for overloaded functions.

Performance:

• Incremental error collation, which helps IDE performance when you have a lot of suppressed errors, is now the default.
• Optimized the way we generate global types for normal source files. You might see a reduction in checking times (3-9% as measured internally at Meta).
• Optimized the way we analyze syntactic environment required for type checking. On a large file like this, it improves the checking time from 4s to 2s.
• Optimized substitution performance when conditional type and mapped types are operating on large and deep objects.

Library Definitions:

• Updated IntersectionObserver types.
• IndexedDB transaction now allows consuming storeNames as DOMStringList.
• Added options to IndexedDB transaction.
• Added durability to IDBTransaction.