Merge branch 'master' into fix-interface-delimiters

.README/README.md

@@ -1,5 +1,6 @@
 # eslint-plugin-flowtype
 
+[![GitSpo Mentions](https://gitspo.com/badges/mentions/gajus/eslint-plugin-flowtype?style=flat-square)](https://gitspo.com/mentions/gajus/eslint-plugin-flowtype)
 [![NPM version](http://img.shields.io/npm/v/eslint-plugin-flowtype.svg?style=flat-square)](https://www.npmjs.org/package/eslint-plugin-flowtype)
 [![Travis build status](http://img.shields.io/travis/gajus/eslint-plugin-flowtype/master.svg?style=flat-square)](https://travis-ci.org/gajus/eslint-plugin-flowtype)
 [![js-canonical-style](https://img.shields.io/badge/code%20style-canonical-blue.svg?style=flat-square)](https://github.com/gajus/canonical)
@@ -21,7 +22,7 @@ npm install eslint --save-dev
 npm install babel-eslint --save-dev
 npm install eslint-plugin-flowtype --save-dev
 
-# Or all at once: 
+# Or all at once:
 npm install eslint babel-eslint eslint-plugin-flowtype --save-dev
 ```
 
@@ -62,6 +63,7 @@ npm install eslint babel-eslint eslint-plugin-flowtype --save-dev
       "comma"
     ],
     "flowtype/require-parameter-type": 2,
+    "flowtype/require-readonly-react-props": 0,
     "flowtype/require-return-type": [
       2,
       "always",
@@ -154,6 +156,7 @@ When `true`, only checks files with a [`@flow` annotation](http://flowtype.org/d
 
 {"gitdown": "include", "file": "./rules/array-style-complex-type.md"}
 {"gitdown": "include", "file": "./rules/array-style-simple-type.md"}
+{"gitdown": "include", "file": "./rules/arrow-parens.md"}
 {"gitdown": "include", "file": "./rules/boolean-style.md"}
 {"gitdown": "include", "file": "./rules/define-flow-type.md"}
 {"gitdown": "include", "file": "./rules/delimiter-dangle.md"}
@@ -171,7 +174,9 @@ When `true`, only checks files with a [`@flow` annotation](http://flowtype.org/d
 {"gitdown": "include", "file": "./rules/object-type-delimiter.md"}
 {"gitdown": "include", "file": "./rules/require-compound-type-alias.md"}
 {"gitdown": "include", "file": "./rules/require-exact-type.md"}
+{"gitdown": "include", "file": "./rules/require-inexact-type.md"}
 {"gitdown": "include", "file": "./rules/require-parameter-type.md"}
+{"gitdown": "include", "file": "./rules/require-readonly-react-props.md"}
 {"gitdown": "include", "file": "./rules/require-return-type.md"}
 {"gitdown": "include", "file": "./rules/require-types-at-top.md"}
 {"gitdown": "include", "file": "./rules/require-valid-file-annotation.md"}

.README/rules/arrow-parens.md

@@ -0,0 +1,18 @@
+### `arrow-parens`
+
+_The `--fix` option on the command line automatically fixes problems reported by this rule._
+
+Enforces the consistent use of parentheses in arrow functions.
+
+This rule has a string option and an object one.
+
+String options are:
+
+- `"always"` (default) requires parens around arguments in all cases.
+- `"as-needed"` enforces no braces where they can be omitted.
+
+Object properties for variants of the `"as-needed"` option:
+
+- `"requireForBlockBody": true` modifies the as-needed rule in order to require parens if the function body is in an instructions block (surrounded by braces).
+
+<!-- assertions arrowParens -->

.README/rules/require-inexact-type.md

@@ -0,0 +1,32 @@
+### `require-inexact-type`
+
+This rule enforces explicit inexact object types.
+
+#### Options
+
+The rule has one string option:
+
+- `"always"` (default): Report all object type definitions that aren't explicit inexact, but ignore exact objects.
+- `"never"`: Report all object type definitions that are explicit inexact.
+
+```js
+{
+  "rules": {
+    "flowtype/require-inexact-type": [
+      2,
+      "always"
+    ]
+  }
+}
+
+{
+  "rules": {
+    "flowtype/require-inexact-type": [
+      2,
+      "never"
+    ]
+  }
+}
+```
+
+<!-- assertions requireInexactType -->

.README/rules/require-readonly-react-props.md

@@ -0,0 +1,82 @@
+### `require-readonly-react-props`
+
+This rule validates that React props are marked as $ReadOnly. React props are immutable and modifying them could lead to unexpected results. Marking prop shapes as $ReadOnly avoids these issues.
+
+The rule tries its best to work with both class and functional components. For class components, it does a fuzzy check for one of "Component", "PureComponent", "React.Component" and "React.PureComponent". It doesn't actually infer that those identifiers resolve to a proper `React.Component` object.
+
+For example, this will NOT be checked:
+
+```js
+import MyReact from 'react';
+class Foo extends MyReact.Component { }
+```
+
+As a result, you can safely use other classes without getting warnings from this rule:
+
+```js
+class MyClass extends MySuperClass { }
+```
+
+React's functional components are hard to detect statically. The way it's done here is by searching for JSX within a function. When present, a function is considered a React component:
+
+```js
+// this gets checked
+type Props = { };
+function MyComponent(props: Props) {
+    return <p />;
+}
+
+// this doesn't get checked since no JSX is present in a function
+type Options = { };
+function SomeHelper(options: Options) {
+    // ...
+}
+
+// this doesn't get checked since no JSX is present directly in a function
+function helper() { return <p /> }
+function MyComponent(props: Props) {
+    return helper();
+}
+```
+
+The rule only works for locally defined props that are marked with a `$ReadOnly` or using covariant notation. It doesn't work with imported props:
+
+```js
+// the rule has no way of knowing whether ImportedProps are read-only
+import { type ImportedProps } from './somewhere';
+class Foo extends React.Component<ImportedProps> { }
+
+
+// the rule also checks for covariant properties
+type Props = {|
+    +foo: string
+|};
+class Bar extends React.Component<Props> { }
+
+// this fails because the object is not fully read-only
+type Props = {|
+    +foo: string,
+    bar: number,
+|};
+class Bar extends React.Component<Props> { }
+
+// this fails because spreading makes object mutable (as of Flow 0.98)
+// https://github.com/gajus/eslint-plugin-flowtype/pull/400#issuecomment-489813899
+type Props = {|
+    +foo: string,
+    ...bar,
+|};
+class Bar extends React.Component<Props> { }
+```
+
+
+```js
+{
+    "rules": {
+        "flowtype/require-readonly-react-props": 2
+    }
+}
+```
+
+
+<!-- assertions requireReadonlyReactProps -->

.README/rules/require-valid-file-annotation.md

@@ -18,6 +18,10 @@ This rule has an object option:
     * `"line"`: Require single line annotations (i.e. `// @flow`).
     * `"block"`: Require block annotations (i.e. `/* @flow */`).
 
+* `"strict"` - Enforce a strict flow file annotation.
+    * `false` (default): strict flow annotation is not required.
+    * `true`: Require strict flow annotation (i.e. `// @flow strict`).
+
 ```js
 {
   "rules": {
@@ -34,6 +38,7 @@ This rule has an object option:
       2,
       "always", {
         "annotationStyle": "block"
+        "strict": true,
       }
     ]
   }

.eslintrc

@@ -1,3 +1,6 @@
 {
-  "extends": "canonical"
+  "extends": "canonical",
+  "rules": {
+    "unicorn/prevent-abbreviations": 0
+  }
 }

.github/FUNDING.yml

@@ -0,0 +1,2 @@
+github: gajus
+patreon: gajus

.gitignore

@@ -11,3 +11,4 @@ dist
 !.README
 !.travis.yml
 /package-lock.json
+/yack.lock