⭐️New: Add vue/valid-slot-scope rule

docs/rules/README.md

@@ -136,6 +136,7 @@ For example:
 | Rule ID | Description |    |
 |:--------|:------------|:---|
 | [vue/script-indent](./script-indent.md) | enforce consistent indentation in `<script>` | :wrench: |
+| [vue/valid-slot-scope](./valid-slot-scope.md) | enforce valid `slot-scope` attributes |  |
 
 ## Deprecated
 

docs/rules/valid-slot-scope.md

@@ -0,0 +1,74 @@
+---
+pageClass: rule-details
+sidebarDepth: 0
+title: vue/valid-slot-scope
+description: enforce valid `slot-scope` attributes
+---
+# vue/valid-slot-scope
+> enforce valid `slot-scope` attributes
+
+This rule checks whether every `slot-scope` (or `scope`) attributes is valid.
+
+## :book: Rule Details
+
+This rule reports `slot-scope` attributes in the following cases:
+
+- The `slot-scope` attribute does not have that attribute value. E.g. `<div slot-scope></div>`
+
+<eslint-code-block :rules="{'vue/valid-slot-scope': ['error']}">
+```vue
+<template>
+  <!-- ✓ GOOD -->
+  <TheComponent>
+    <template slot-scope="prop">
+      ...
+    </template>
+  </TheComponent>
+  <TheComponent>
+    <template slot-scope="{ a, b, c }">
+      ...
+    </template>
+  </TheComponent>
+  <TheComponent>
+    <template slot-scope="[ a, b, c ]">
+      ...
+    </template>
+  </TheComponent>
+
+  <!-- ✗ BAD -->
+  <TheComponent>
+    <template slot-scope>
+      ...
+    </template>
+  </TheComponent>
+  <TheComponent>
+    <template slot-scope="">
+      ...
+    </template>
+  </TheComponent>
+</template>
+```
+</eslint-code-block>
+
+::: warning Note
+This rule does not check syntax errors in directives because it's checked by [no-parsing-error] rule.
+:::
+
+## :wrench: Options
+
+Nothing.
+
+## :couple: Related rules
+
+- [no-parsing-error]
+
+## :books: Further reading
+
+- [Guide - Scoped Slots](https://vuejs.org/v2/guide/components-slots.html#Scoped-Slots)
+
+[no-parsing-error]: no-parsing-error.md
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/vuejs/eslint-plugin-vue/blob/master/lib/rules/valid-slot-scope.js)
+- [Test source](https://github.com/vuejs/eslint-plugin-vue/blob/master/tests/lib/rules/valid-slot-scope.js)

lib/index.js

@@ -55,6 +55,7 @@ module.exports = {
     'use-v-on-exact': require('./rules/use-v-on-exact'),
     'v-bind-style': require('./rules/v-bind-style'),
     'v-on-style': require('./rules/v-on-style'),
+    'valid-slot-scope': require('./rules/valid-slot-scope'),
     'valid-template-root': require('./rules/valid-template-root'),
     'valid-v-bind': require('./rules/valid-v-bind'),
     'valid-v-cloak': require('./rules/valid-v-cloak'),

lib/rules/valid-slot-scope.js

@@ -0,0 +1,91 @@
+/**
+ * @fileoverview enforce valid `slot-scope` attributes
+ * @author Yosuke Ota
+ */
+'use strict'
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const utils = require('../utils')
+
+// ------------------------------------------------------------------------------
+// Helpers
+// ------------------------------------------------------------------------------
+
+/**
+ * Check whether the given token is a quote.
+ * @param {Token} token The token to check.
+ * @returns {boolean} `true` if the token is a quote.
+ */
+function isQuote (token) {
+  return token != null && token.type === 'Punctuator' && (token.value === '"' || token.value === "'")
+}
+
+/**
+ * Check whether the value of the given slot-scope node is a syntax error.
+ * @param {ASTNode} node The slot-scope node to check.
+ * @param {TokenStore} tokenStore The TokenStore.
+ * @returns {boolean} `true` if the value is a syntax error
+ */
+function isSyntaxError (node, tokenStore) {
+  if (node.value == null) {
+    // does not have value.
+    return false
+  }
+  if (node.value.expression != null) {
+    return false
+  }
+  const tokens = tokenStore.getTokens(node.value)
+  if (!tokens.length) {
+    // empty value
+    return false
+  }
+  if (tokens.length === 2 && tokens.every(isQuote)) {
+    // empty value e.g `""` / `''`
+    return false
+  }
+  return true
+}
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    docs: {
+      description: 'enforce valid `slot-scope` attributes',
+      category: undefined,
+      url: 'https://github.com/vuejs/eslint-plugin-vue/blob/v5.0.0/docs/rules/valid-slot-scope.md'
+    },
+    fixable: null,
+    schema: [],
+    messages: {
+      expectedValue: "'{{attrName}}' attributes require a value."
+    }
+  },
+
+  create (context) {
+    const tokenStore =
+      context.parserServices.getTemplateBodyTokenStore &&
+      context.parserServices.getTemplateBodyTokenStore()
+    return utils.defineTemplateBodyVisitor(context, {
+      'VAttribute[directive=true][key.name=/^(slot-)?scope$/]' (node) {
+        if (!utils.hasAttributeValue(node)) {
+          if (isSyntaxError(node, tokenStore)) {
+            // syntax error
+            return
+          }
+          context.report({
+            node,
+            loc: node.loc,
+            messageId: 'expectedValue',
+            data: { attrName: node.key.name }
+          })
+        }
+      }
+    })
+  }
+}