From 45643b7cd5b6101fb6a87a932ebff39b04d5eaf9 Mon Sep 17 00:00:00 2001
From: yosuke ota <otameshiyo23@gmail.com>
Date: Thu, 31 Jan 2019 22:34:22 +0900
Subject: [PATCH] fix(no-unused-components): crash when `:is` in `<component>`
 is empty

Fixed #789
---
 lib/rules/no-unused-components.js       |  6 ++-
 tests/lib/rules/no-unused-components.js | 54 +++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/lib/rules/no-unused-components.js b/lib/rules/no-unused-components.js
index 4382cbbca..a12b7d43d 100644
--- a/lib/rules/no-unused-components.js
+++ b/lib/rules/no-unused-components.js
@@ -56,7 +56,11 @@ module.exports = {
         usedComponents.add(node.rawName)
       },
       "VAttribute[directive=true][key.name='bind'][key.argument='is']" (node) {
-        if (node.value.type !== 'VExpressionContainer') return
+        if (
+          !node.value ||  // `<component :is>`
+          node.value.type !== 'VExpressionContainer' ||
+          !node.value.expression  // `<component :is="">`
+        ) return
 
         if (node.value.expression.type === 'Literal') {
           usedComponents.add(node.value.expression.value)
diff --git a/tests/lib/rules/no-unused-components.js b/tests/lib/rules/no-unused-components.js
index f62b83fb1..b8dfcaaf2 100644
--- a/tests/lib/rules/no-unused-components.js
+++ b/tests/lib/rules/no-unused-components.js
@@ -411,6 +411,22 @@ tester.run('no-unused-components', rule, {
           }
         }
       </script>`
+    },
+
+    // empty `:is`
+    {
+      filename: 'test.vue',
+      code: `
+      <template>
+        <component :is=""></component>
+      </template>`
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      <template>
+        <component :is></component>
+      </template>`
     }
   ],
   invalid: [
@@ -512,6 +528,44 @@ tester.run('no-unused-components', rule, {
         message: 'The "Bar" component has been registered but not used.',
         line: 14
       }]
+    },
+
+    // empty `:is`
+    {
+      filename: 'test.vue',
+      code: `
+      <template>
+        <component :is=""></component>
+      </template>
+      <script>
+        export default {
+          components: {
+            Foo,
+          },
+        }
+      </script>`,
+      errors: [{
+        message: 'The "Foo" component has been registered but not used.',
+        line: 8
+      }]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      <template>
+        <component :is></component>
+      </template>
+      <script>
+        export default {
+          components: {
+            Foo,
+          },
+        }
+      </script>`,
+      errors: [{
+        message: 'The "Foo" component has been registered but not used.',
+        line: 8
+      }]
     }
   ]
 })