From 92a159d939c1cb93fd372c2fd878f01b7dd522ca Mon Sep 17 00:00:00 2001
From: Joe Haddad <joe.haddad@zeit.co>
Date: Wed, 20 May 2020 11:57:18 -0400
Subject: [PATCH] Correctly eliminate destructuring assignment (#13144)

This eliminates code referenced via destructuring assignment, as reported by @styfle.
---
 .../build/babel/plugins/next-ssg-transform.ts | 76 +++++++++++++++----
 .../babel-plugin-next-ssg-transform.test.js   | 24 ++++++
 2 files changed, 87 insertions(+), 13 deletions(-)

diff --git a/packages/next/build/babel/plugins/next-ssg-transform.ts b/packages/next/build/babel/plugins/next-ssg-transform.ts
index cea149d7cd..9bdd35ad73 100644
--- a/packages/next/build/babel/plugins/next-ssg-transform.ts
+++ b/packages/next/build/babel/plugins/next-ssg-transform.ts
@@ -189,13 +189,33 @@ export default function nextTransformSsg({
           path.traverse(
             {
               VariableDeclarator(path, state) {
-                if (path.node.id.type !== 'Identifier') {
-                  return
-                }
+                if (path.node.id.type === 'Identifier') {
+                  const local = path.get('id') as NodePath<
+                    BabelTypes.Identifier
+                  >
+                  if (isIdentifierReferenced(local)) {
+                    state.refs.add(local)
+                  }
+                } else if (path.node.id.type === 'ObjectPattern') {
+                  const pattern = path.get('id') as NodePath<
+                    BabelTypes.ObjectPattern
+                  >
 
-                const local = path.get('id') as NodePath<BabelTypes.Identifier>
-                if (isIdentifierReferenced(local)) {
-                  state.refs.add(local)
+                  const properties = pattern.get('properties')
+                  properties.forEach((p) => {
+                    const local = p.get(
+                      p.node.type === 'ObjectProperty'
+                        ? 'value'
+                        : p.node.type === 'RestElement'
+                        ? 'argument'
+                        : (function () {
+                            throw new Error('invariant')
+                          })()
+                    ) as NodePath<BabelTypes.Identifier>
+                    if (isIdentifierReferenced(local)) {
+                      state.refs.add(local)
+                    }
+                  })
                 }
               },
               FunctionDeclaration: markFunction,
@@ -319,14 +339,44 @@ export default function nextTransformSsg({
             path.traverse({
               // eslint-disable-next-line no-loop-func
               VariableDeclarator(path) {
-                if (path.node.id.type !== 'Identifier') {
-                  return
-                }
+                if (path.node.id.type === 'Identifier') {
+                  const local = path.get('id') as NodePath<
+                    BabelTypes.Identifier
+                  >
+                  if (refs.has(local) && !isIdentifierReferenced(local)) {
+                    ++count
+                    path.remove()
+                  }
+                } else if (path.node.id.type === 'ObjectPattern') {
+                  const pattern = path.get('id') as NodePath<
+                    BabelTypes.ObjectPattern
+                  >
 
-                const local = path.get('id') as NodePath<BabelTypes.Identifier>
-                if (refs.has(local) && !isIdentifierReferenced(local)) {
-                  ++count
-                  path.remove()
+                  const beforeCount = count
+                  const properties = pattern.get('properties')
+                  properties.forEach((p) => {
+                    const local = p.get(
+                      p.node.type === 'ObjectProperty'
+                        ? 'value'
+                        : p.node.type === 'RestElement'
+                        ? 'argument'
+                        : (function () {
+                            throw new Error('invariant')
+                          })()
+                    ) as NodePath<BabelTypes.Identifier>
+
+                    if (refs.has(local) && !isIdentifierReferenced(local)) {
+                      ++count
+                      p.remove()
+                    }
+                  })
+
+                  if (
+                    beforeCount !== count &&
+                    pattern.get('properties').length < 1
+                  ) {
+                    path.remove()
+                  }
                 }
               },
               FunctionDeclaration: sweepFunction,
diff --git a/test/unit/babel-plugin-next-ssg-transform.test.js b/test/unit/babel-plugin-next-ssg-transform.test.js
index 7acba93216..a81c6f358c 100644
--- a/test/unit/babel-plugin-next-ssg-transform.test.js
+++ b/test/unit/babel-plugin-next-ssg-transform.test.js
@@ -452,5 +452,29 @@ describe('babel plugin (next-ssg-transform)', () => {
         `"export var __N_SSG=true;export default function Home(){return __jsx(\\"div\\",null);}"`
       )
     })
+
+    it('destructuring assignment (object)', () => {
+      const output = babel(trim`
+        import fs from 'fs';
+        import other from 'other';
+
+        const {readFile, readdir, access: foo} = fs.promises;
+        const {a,b, cat: bar,...rem} = other;
+
+        export async function getStaticProps() {
+          readFile;
+          readdir;
+          foo;
+          b;
+          cat;
+          rem;
+        }
+        export default function Home() { return <div />; }
+      `)
+
+      expect(output).toMatchInlineSnapshot(
+        `"import other from'other';const{a,cat:bar}=other;export var __N_SSG=true;export default function Home(){return __jsx(\\"div\\",null);}"`
+      )
+    })
   })
 })