[flow] Bump flow and migrate away from legacy syntax

.eslintrc

@@ -3,7 +3,7 @@
     "react": {
       "pragma": "React",
       "version": "19.0",
-      "flowVersion": "0.270.0" // Flow version
+      "flowVersion": "0.314.0" // Flow version
     }
   },
   // babel parser to support ES6/7 features

.flowconfig

@@ -1,5 +1,5 @@
 [version]
-0.307.1
+0.314.0
 
 [ignore]
 .*/malformed_package_json/.*
@@ -18,7 +18,7 @@ module.system.node.resolve_dirname=flow_modules
 module.system.node.resolve_dirname=node_modules
 react.runtime=automatic
 
-experimental.ts_utility_syntax=true
+experimental.allow_variance_keywords=true
 experimental.deprecated_utilities='$ReadOnlyArray' -> '<PROJECT_ROOT>/'
 experimental.deprecated_utilities='$NonMaybeType' -> '<PROJECT_ROOT>/'
 experimental.deprecated_utilities='$ReadOnly' -> '<PROJECT_ROOT>/'

package.json

@@ -26,18 +26,18 @@
     "@babel/preset-flow": "^7.27.1",
     "@babel/preset-react": "^7.27.1",
     "babel-jest": "^29.7.0",
-    "babel-plugin-syntax-hermes-parser": "^0.25.1",
+    "babel-plugin-syntax-hermes-parser": "^0.36.1",
     "del-cli": "^5.0.0",
     "eslint": "^8.57.0",
     "eslint-config-prettier": "^8.9.0",
     "eslint-plugin-ft-flow": "^3.0.7",
     "eslint-plugin-promise": "^6.0.0",
     "eslint-plugin-react": "^7.33.1",
     "eslint-plugin-react-hooks": "6.1.0-canary-12bc60f5-20250613",
-    "flow-api-translator": "^0.32.1",
-    "flow-bin": "^0.307.1",
+    "flow-api-translator": "^0.36.1",
+    "flow-bin": "^0.314.0",
     "glob": "^11.1.0",
-    "hermes-eslint": "^0.32.0",
+    "hermes-eslint": "^0.36.1",
     "husky": "^8.0.0",
     "jest": "^29.7.0",
     "jest-environment-jsdom": "^29.7.0",
@@ -46,11 +46,11 @@
     "npm-run-all": "^4.1.3",
     "patch-package": "^8.0.0",
     "prettier": "^3.3.3",
-    "prettier-plugin-hermes-parser": "0.25.0",
+    "prettier-plugin-hermes-parser": "0.36.1",
     "yargs": "17.7.2"
   },
   "engines": {
-    "node": ">=20.11.0",
+    "node": ">=20.19.0",
     "npm": ">=10.0.0"
   },
   "workspaces": [

packages/react-strict-dom/src/types/Utilities.js

@@ -7,4 +7,6 @@
  * @flow strict
  */
 
-export type ReactRef<T> = { -current: T | null, ... } | ((T | null) => unknown);
+export type ReactRef<T> =
+  | { writeonly current: T | null, ... }
+  | ((T | null) => unknown);

packages/react-strict-dom/src/types/react.js

@@ -10,5 +10,5 @@
 import * as React from 'react';
 
 export type CallbackRef<T> = (node: T | null) => unknown;
-export type ObjectRef<T> = { -current: T, ... };
+export type ObjectRef<T> = { writeonly current: T, ... };
 export type Ref<T> = CallbackRef<T> | ObjectRef<T | null> | React.RefObject<T>;

packages/react-strict-dom/src/types/styles.js

@@ -20,7 +20,7 @@ import typeof * as TStyleX from '@stylexjs/stylex';
 export type Style = InlineStyles;
 
 export type Styles = StyleXArray<
-  StyleXStyles<> | Theme<VarGroup<{ +[string]: unknown }>>
+  StyleXStyles<> | Theme<VarGroup<{ readonly [string]: unknown }>>
 >;
 
 export type IStyleX = Readonly<{

packages/react-strict-dom/src/web/css/merge.js

@@ -21,7 +21,7 @@ type InlineStyle = Readonly<{
   [key: string]: string
 }>;
 
-type StylesArray<+T> = T | ReadonlyArray<StylesArray<T>>;
+type StylesArray<out T> = T | ReadonlyArray<StylesArray<T>>;
 
 type Props = Readonly<{
   className?: string,

packages/scripts/package.json

@@ -8,7 +8,7 @@
     "generate-types": "./generate-types.js"
   },
   "dependencies": {
-    "flow-api-translator": "^0.25.0",
+    "flow-api-translator": "^0.36.1",
     "yargs": "17.7.2"
   }
 }