Add vue/require-explicit-emits rule

Author: ota-meshi

Diff for: docs/rules/README.md

@@ -286,6 +286,7 @@ For example:
 | [vue/object-curly-spacing](./object-curly-spacing.md) | enforce consistent spacing inside braces | :wrench: |
 | [vue/padding-line-between-blocks](./padding-line-between-blocks.md) | require or disallow padding lines between blocks | :wrench: |
 | [vue/require-direct-export](./require-direct-export.md) | require the component to be directly exported |  |
+| [vue/require-explicit-emits](./require-explicit-emits.md) | require `emits` option with name triggered by `$emit()` |  |
 | [vue/require-name-property](./require-name-property.md) | require a name property in Vue components |  |
 | [vue/script-indent](./script-indent.md) | enforce consistent indentation in `<script>` | :wrench: |
 | [vue/sort-keys](./sort-keys.md) | enforce sort-keys in a manner that is compatible with order-in-components |  |

Diff for: docs/rules/no-deprecated-vue-config-keycodes.md

@@ -13,7 +13,7 @@ description: disallow using deprecated `Vue.config.keyCodes` (in Vue.js 3.0.0+)
 
 This rule reports use of deprecated `Vue.config.keyCodes` (in Vue.js 3.0.0+)
 
-<eslint-code-block filename="a.js" language="javascript ":rules="{'vue/no-deprecated-vue-config-keycodes': ['error']}">
+<eslint-code-block filename="a.js" language="javascript" :rules="{'vue/no-deprecated-vue-config-keycodes': ['error']}">
 
 ```js
 /* ✗ BAD */
@@ -31,14 +31,16 @@ Nothing.
 ## :couple: Related rules
 
 - [vue/no-deprecated-v-on-number-modifiers]
-- [API - Global Config - keyCodes]
 
 [vue/no-deprecated-v-on-number-modifiers]: ./no-deprecated-v-on-number-modifiers.md
-[API - Global Config - keyCodes]: https://vuejs.org/v2/api/#keyCodes
 
 ## :books: Further reading
 
-- [Vue RFCs - 0014-drop-keycode-support](https://github.com/vuejs/rfcs/blob/master/active-rfcs/0014-drop-keycode-support.md)
+- [Vue RFCs - 0014-drop-keycode-support]
+- [API - Global Config - keyCodes]
+
+[Vue RFCs - 0014-drop-keycode-support]: https://github.com/vuejs/rfcs/blob/master/active-rfcs/0014-drop-keycode-support.md
+[API - Global Config - keyCodes]: https://vuejs.org/v2/api/#keyCodes
 
 ## :mag: Implementation
 

Diff for: docs/rules/require-explicit-emits.md

@@ -0,0 +1,84 @@
+---
+pageClass: rule-details
+sidebarDepth: 0
+title: vue/require-explicit-emits
+description: require `emits` option with name triggered by `$emit()`
+---
+# vue/require-explicit-emits
+> require `emits` option with name triggered by `$emit()`
+
+## :book: Rule Details
+
+This rule reports event triggers not declared with the `emits` option. (The `emits` option is a new in Vue.js 3.0.0+)
+
+Explicit `emits` declaration serves as self-documenting code. This can be useful for other developers to instantly understand what events the component is supposed to emit.
+Also,  with attribute fallthrough changes in Vue.js 3.0.0+, `v-on` listeners on components will fallthrough as native listeners by default. Declare it as a component-only event in `emits` to avoid unnecessary registration of native listeners.
+
+<eslint-code-block :rules="{'vue/require-explicit-emits': ['error']}">
+
+```vue
+<template>
+  <!-- ✓ GOOD -->
+  <div @click="$emit('good')"/>
+  <!-- ✗ BAD -->
+  <div @click="$emit('bad')"/>
+</template>
+<script>
+export default {
+  emits: ['good']
+}
+</script>
+```
+
+</eslint-code-block>
+
+<eslint-code-block :rules="{'vue/require-explicit-emits': ['error']}">
+
+```vue
+<script>
+export default {
+  emits: ['good'],
+  methods: {
+    foo () {
+      // ✓ GOOD
+      this.$emit('good')
+      // ✗ BAD
+      this.$emit('bad')
+    }
+  }
+}
+</script>
+```
+
+</eslint-code-block>
+
+<eslint-code-block :rules="{'vue/require-explicit-emits': ['error']}">
+
+```vue
+<script>
+export default {
+  emits: ['good'],
+  setup (props, context) {
+    // ✓ GOOD
+    context.emit('good')
+    // ✗ BAD
+    context.emit('bad')
+  }
+}
+</script>
+```
+
+</eslint-code-block>
+
+## :wrench: Options
+
+Nothing.
+
+## :books: Further reading
+
+- [Vue RFCs - 0030-emits-option](https://github.com/vuejs/rfcs/blob/master/active-rfcs/0030-emits-option.md)
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/vuejs/eslint-plugin-vue/blob/master/lib/rules/require-explicit-emits.js)
+- [Test source](https://github.com/vuejs/eslint-plugin-vue/blob/master/tests/lib/rules/require-explicit-emits.js)

Diff for: lib/index.js

@@ -87,6 +87,7 @@ module.exports = {
     'require-component-is': require('./rules/require-component-is'),
     'require-default-prop': require('./rules/require-default-prop'),
     'require-direct-export': require('./rules/require-direct-export'),
+    'require-explicit-emits': require('./rules/require-explicit-emits'),
     'require-name-property': require('./rules/require-name-property'),
     'require-prop-type-constructor': require('./rules/require-prop-type-constructor'),
     'require-prop-types': require('./rules/require-prop-types'),

Diff for: lib/rules/no-setup-props-destructure.js

@@ -83,7 +83,8 @@ module.exports = {
         ':function' (node) {
           scopeStack = { upper: scopeStack, functionNode: node }
         },
-        ':function>*' (node) {
+        ':function > Identifier' (node) {
+          // find `setup(*props*)`
           const setupFunctionData = setupFunctions.get(node.parent)
           if (!setupFunctionData || setupFunctionData.propsParam !== node) {
             return