Release v0.98.0 · facebook/flow

Likely to cause new Flow errors:

Infer void before typechecking starts for functions without a return statement, lessening the impact of a union typechecking bug (#7322).
Fix a bug which prevented Flow from asking for required type annotations.
Turn the deprecated-utility lint on by default.
Two related changes to type refinements to fix unsoundness:
- mixed refined to an array produces a read-only array.
- mixed refined to an object produces a read-only object.

New Features:

Add the ability to exclude paths included by a previous pattern in a .flowconfig (#7317).

Notable bug fixes:

Misc:

Exclude deprecated-utility and dynamic-export lints when applying all=setting rules (#7473).
Improve client/server version mismatch behavior so that the newest of the two is preserved, rather than the client version.
Preserve exactness of the input type when using $ObjMap or $ObjMapi (#7642).
Minor changes to metadata in the results of flow type-at-pos --json.
Batch DidOpen notifications from the IDE in order to make checking in IDE lazy mode more efficient.
When flow lsp automatically starts a server, it prefers the lazy mode set in a .flowconfig to the lazy mode passed on the CLI.
Allow lints to be explicitly set to their defaults (normally redundant lint settings are disallowed).
Fix spurious missing annotation errors when the this type is used incorrectly.
Fix a bug that made React.Element behave differently than React$Element.
Fix an edge case where object property assignments were typechecked incorrectly (#7618).
Fix an unsoundness with addition or logical operators when combined with generics (#6671, #7070).
Fix an issue which allowed read-only arrays to be written to if the index was of type any.
Fix a bug which stymied typechecking after try/catch blocks (#7530).

Libdefs:

Provide feedback