v0.250.0

Likely to cause new Flow errors:

• Fix a bug where scope analysis of exported component type is done incorrectly, which causes generics mentioned within component type to be incorrectly typed as any.

Notable bug fixes:

• We will now remove previous props in generic component types in type argument inference. example
• When all option is specified in the config of flow-remove-types, we now respect it and will correctly handle Flow-typed files without @flow pragma.

v0.249.0

Likely to cause new Flow errors:

• Uses of React$AbstractComponent outside library definitions will now trigger internal-type lint error, which is on by default. React.AbstractComponent is also marked as deprecated. We recommend replacing them with component types. We have provided a codemod via the flow-upgrade package to aid larger codebases with this conversion: yarn run flow-codemod eliminateAbstractComponent path/to/src.

Notable bug fixes:

• Fixed issue with StringPrefix and StringSuffix when used as a component syntax prop.
• Fixed an issue that causes type argument inference on component type to be incorrectly under-constrained. (example)
• Fixed as cast support in flow-remove-types.

Library Definitions:

• React string refs are no longer supported in React.cloneElement. e.g. React.cloneElement(e, {ref: 'foo'}) will be an error.
• The deprecated React$Ref type and various aliases of it are removed.

v0.248.1

IDE:

• React.Component annotated exported will now also show up in auto-imports in a type position.

v0.248.0

Breaking changes:

• Support for long deprecated predicate function (%checks) is removed. It will still parse, but all of them will error with unsupported-syntax, and %checks will be completely ignored for type checking purpose as if it doesn't exist.
• $TupleMap support is now removed. $TupleMap will now resolve to the global definition is there is one, or it will fail and the type becomes any.

Likely to cause new Flow errors:

• Support for the unsound $TEMPORARY$* types is dropped. If your codebase happens to have any of these types, you can replace them with there sound and well-documented equivalents:
  • Replace $TEMPORARY$object<{props}> with $ReadOnly<{props}> or {props}
  • Replace $TEMPORARY$array<T> with $ReadOnlyArray<T> or Array<T>
  • Replace $TEMPORARY$number<42> with number or '42'
  • Replace $TEMPORARY$string<"foo"> with string or "foo"
  • We have provided a flow-runner codemod via the flow-upgrade package to aid larger codebases with this conversion: yarn run flow-codemod replaceTemporaryTypes path/to/src.
• The inferred type for Object.freeze({ A: 'a', B: 'b' }) is now {+A:'a',+B:'b'} both locally within a file and when the object is being exported. This replaces an earlier unsound behavior where the type of A would opportunistically behaved either as string or 'a' depending on the context where it appeared.
• React string refs are now banned.
• contextTypes and childContextTypes in react class components are now empty typed, so declaring legacy context in React will be an error.
• Component syntax component and component types' ref prop now must have React.RefSetter<...> type.

Parser:

• Component type in parentheses can now be correctly parsed. e.g. type Foo = (component(x: number) renders Bar);
• Trailing comma is now allowed after rest parameter in component syntax components and component types.
• The v regex flag is now supported.

IDE:

• We now provide a code action to stub out a react component, at the location of an unbound JSX identifier.
• Component declaration/type without renders clause will no longer show renders React.Node on hover.
• Hovering on components will now consistently show its props and renders information. Previously, the information is omitted for component declarations.
• If we see : renders <annot> at the position that expects a render declaration, the quickfix will suggest removing : instead of replacing : with renders.

Library Definitions:

• Added type for util.stripVTControlCharacters for NodeJS.

v0.247.1

Misc:

• Performance optimization for unions

v0.247.0

Breaking changes:

• Support for the deprecated $Call type is removed. $Call will now resolve to whatever $Call points to in the global libdef. If you need more time to migrate, you can create a shim like $Call<F, T> = $TupleMap<[T], F>[0], but please note that we intend to remove support for $TupleMap eventually.
• deprecated-type-dollar-call lint is removed, since the support for $Call is removed.
• react.disable_function_components_default_props config option is removed. It is on by default since v0.238.

Likely to cause new Flow errors:

• $TupleMap is deprecated and will be soon removed, now that mapped type works on array inputs. Existing $TupleMap will still work in this release, but every use will trigger a deprecated-type lint that is on by default.
• Flow now performs literal subtyping checks for strict equality conditions in non-refinement contexts. example
• Fixed destructuring with invalid literal defaults. The following now errors properly: example
• Using string ref on components that are definitely not a class component is now an error. example
• React utility types will no longer incorrectly accept hook types when they expect component types. e.g. type A = React$ElementConfig<hook (props: {foo: string}) => void>; will now error.

New Features:

• Refinements against negated bigint literals should now work.

Notable bug fixes:

• Mapped type on generic arrays is now supported. Previously it will fail with array is not an object error.
• flow-remove-types now correctly handles as cast with generics.

IDE:

• On hover, values that have React.AbstractComponent type will be shown in the component type syntax
• Flow now offers a code action to insert inferred render type when you hover on the name of the component.
• Flow now provides keyword completion for component type, hook types and render types.

Library Definitions:

• Overly restrictive typing of queueMicrotask is now fixed.

v0.246.0

Likely to cause new Flow errors:

• Support for $ObjMap has been completely removed. This change means that:
  • $ObjMap will resolve to a user-defined $ObjMap global if it's available in your libdef. You can use type $ObjMap<O, F> = {[K in keyof O]: $Call<F, O[K]>} to get most of the same behavior, except that in the mapped type version O[K] will include void for optional props. Please note that this should be considered as a permanent shim, because we intend to eventually remove $Call.
  • flow codemod key-mirror command was removed, since this codemod tries to convert $ObjMap to $KeyMirror
  • deprecated-type-objmap lint was removed.
• Component syntax components without ref prop will have void as the instance, so React.ElementRef<component> of such component will return void.

New Features:

• Mapped types now support array and tuple types in the form of {[K in keyof <array or tuple type>: <mapped type>}.
  • With this support, we intend to deprecate $TupleMap in the next release and remove the support for $TupleMap eventually
• You can now refine against variables and member expressions with a literal type, not just literal themselves.

Notable bug fixes:

• Flow now only reports one error when two disjoint large enum-like unions are compared (example).

IDE:

• Code actions on component syntax components will produce smaller targeted edits, rather than reprint the entire component.
• Deprecated utility type like $Call are no longer suggested in autocomplete.
• Flow will now provide a quick fix when the spread prop of a component with component syntax redefines some already defined props.

Library Definitions:

• React.Ref is marked as deprecated. Use React.RefSetter instead for ref props, and React.RefObject for returns of useRef.
• React.RefSetter now includes null and void.
• Promise.all and Promise.allSettled have been updated to use mapped type instead of $TupleMap. The requirement on the type arguments are slightly changed.

v0.245.2

Misc:

• The language for invalidated refinement is slightly tweaked. Instead of saying refactoring to a constant, we now say refactoring to a const variable.

v0.245.1

Website:

• Refined expressions are now highlighted in try-flow playground. Hovering on refined expressions will show where it's refined, and hovering on some invalidated property refinements will show the location and reason of the invalidation.

IDE:

• Flow now responds to textDocument/prepareName LSP request. This ensures that Flow's rename support can be surfaced when multiple VSCode extension adds rename support for JS files.

v0.245.0

Likely to cause new Flow errors:

• React.Element type, deprecated in 0.243.0, is now removed.
• Fixed a bug where refinements are incorrectly not invalidated. example
• Under custom jsx pragma, children is no longer incorrectly added to props. Some spurious errors will be gone. example

New Features:

• Added LSP signature help support for JSX attributes. The feature is triggered with the opening { of a JSX attribute value.
• Flow now allows to configure the typing of jsx creation under the new option react.custom_jsx_typing=true. Under this flag, Flow will type check jsx by through your self-defined global type React$CustomJSXFactory type, which should be a function type that accepts arguments according to jsx spec. e.g. You can write a loose one like type React$CustomJSXFactory = (component: any, props: any, ...children: any) => React.MixedElement

Notable bug fixes:

• Fixed jsdoc attachment to signature help results for overloaded functions. (example)
• Signature help on overloaded functions will show information in the correct order of signatures
• Labels of autocomplete on members will indicate if the property is optional with a "?"
• Fixed a bug where a type-only namespace within a namespace is accidentally dropped. This bug used to make globalThis.React.Node being incorrectly unavailable.
• Fixed poor interaction of "Add missing attributes" quickfix when Linked Editing Range is enabled.
• Clicking on related symbol location on hover will jump to the right location in VSCode. Previously it incorrectly jumped to the position 1 character left of the right location.

IDE:

• Elements of component syntax components (e.g. typeof <A /> where A is in component syntax) will no longer be shown in hover with shorthand syntax like A. Instead, it will be shown as React$Element<typeof A>