From e14f93d1bb967310b7df213c005df3d394fbf00e Mon Sep 17 00:00:00 2001
From: Jeroen Engels <jfm.engels@gmail.com>
Date: Thu, 13 Oct 2016 01:36:08 +0200
Subject: [PATCH] Fix crash when exporting with destructuring and sparse array
 (#170)

* Create reproducible crash when exporting with destructuring and sparse array

* Fix crash when exporting with destructuring and sparse array
---
 src/parser/statement.js                       |   4 +-
 .../actual.js                                 |   1 +
 .../expected.json                             | 164 +++++++++++++++++-
 3 files changed, 162 insertions(+), 7 deletions(-)

diff --git a/src/parser/statement.js b/src/parser/statement.js
index cb61499172..676920fff4 100644
--- a/src/parser/statement.js
+++ b/src/parser/statement.js
@@ -943,7 +943,9 @@ pp.checkDeclaration = function(node) {
     }
   } else if (node.type === "ArrayPattern") {
     for (let elem of node.elements) {
-      this.checkDeclaration(elem);
+      if (elem) {
+        this.checkDeclaration(elem);
+      }
     }
   } else if (node.type === "ObjectProperty") {
     this.checkDeclaration(node.value);
diff --git a/test/fixtures/es2015/modules/duplicate-named-export-destructuring/actual.js b/test/fixtures/es2015/modules/duplicate-named-export-destructuring/actual.js
index baa04e6386..3440d42c6c 100644
--- a/test/fixtures/es2015/modules/duplicate-named-export-destructuring/actual.js
+++ b/test/fixtures/es2015/modules/duplicate-named-export-destructuring/actual.js
@@ -9,3 +9,4 @@ export const [{ foo: [baz3] }, { foo2: [baz4] }] = bar;
 export const { foo: { baz: { qux3 } }, foo2: { baz2: [qux4]} } = bar;
 export const { foo: { baz: { qux5 } }, foo2: { baz2: [{qux6}]} } = bar;
 export const { Foo } = bar;
+export const { foo: [ ,, qux7 ] } = bar;
diff --git a/test/fixtures/es2015/modules/duplicate-named-export-destructuring/expected.json b/test/fixtures/es2015/modules/duplicate-named-export-destructuring/expected.json
index e9bb8a3edc..3d8ba60894 100644
--- a/test/fixtures/es2015/modules/duplicate-named-export-destructuring/expected.json
+++ b/test/fixtures/es2015/modules/duplicate-named-export-destructuring/expected.json
@@ -1,29 +1,29 @@
 {
   "type": "File",
   "start": 0,
-  "end": 481,
+  "end": 522,
   "loc": {
     "start": {
       "line": 1,
       "column": 0
     },
     "end": {
-      "line": 11,
-      "column": 27
+      "line": 12,
+      "column": 40
     }
   },
   "program": {
     "type": "Program",
     "start": 0,
-    "end": 481,
+    "end": 522,
     "loc": {
       "start": {
         "line": 1,
         "column": 0
       },
       "end": {
-        "line": 11,
-        "column": 27
+        "line": 12,
+        "column": 40
       }
     },
     "sourceType": "module",
@@ -2431,6 +2431,158 @@
           ],
           "kind": "const"
         }
+      },
+      {
+        "type": "ExportNamedDeclaration",
+        "start": 482,
+        "end": 522,
+        "loc": {
+          "start": {
+            "line": 12,
+            "column": 0
+          },
+          "end": {
+            "line": 12,
+            "column": 40
+          }
+        },
+        "specifiers": [],
+        "source": null,
+        "declaration": {
+          "type": "VariableDeclaration",
+          "start": 489,
+          "end": 522,
+          "loc": {
+            "start": {
+              "line": 12,
+              "column": 7
+            },
+            "end": {
+              "line": 12,
+              "column": 40
+            }
+          },
+          "declarations": [
+            {
+              "type": "VariableDeclarator",
+              "start": 495,
+              "end": 521,
+              "loc": {
+                "start": {
+                  "line": 12,
+                  "column": 13
+                },
+                "end": {
+                  "line": 12,
+                  "column": 39
+                }
+              },
+              "id": {
+                "type": "ObjectPattern",
+                "start": 495,
+                "end": 515,
+                "loc": {
+                  "start": {
+                    "line": 12,
+                    "column": 13
+                  },
+                  "end": {
+                    "line": 12,
+                    "column": 33
+                  }
+                },
+                "properties": [
+                  {
+                    "type": "ObjectProperty",
+                    "start": 497,
+                    "end": 513,
+                    "loc": {
+                      "start": {
+                        "line": 12,
+                        "column": 15
+                      },
+                      "end": {
+                        "line": 12,
+                        "column": 31
+                      }
+                    },
+                    "method": false,
+                    "shorthand": false,
+                    "computed": false,
+                    "key": {
+                      "type": "Identifier",
+                      "start": 497,
+                      "end": 500,
+                      "loc": {
+                        "start": {
+                          "line": 12,
+                          "column": 15
+                        },
+                        "end": {
+                          "line": 12,
+                          "column": 18
+                        }
+                      },
+                      "name": "foo"
+                    },
+                    "value": {
+                      "type": "ArrayPattern",
+                      "start": 502,
+                      "end": 513,
+                      "loc": {
+                        "start": {
+                          "line": 12,
+                          "column": 20
+                        },
+                        "end": {
+                          "line": 12,
+                          "column": 31
+                        }
+                      },
+                      "elements": [
+                        null,
+                        null,
+                        {
+                          "type": "Identifier",
+                          "start": 507,
+                          "end": 511,
+                          "loc": {
+                            "start": {
+                              "line": 12,
+                              "column": 25
+                            },
+                            "end": {
+                              "line": 12,
+                              "column": 29
+                            }
+                          },
+                          "name": "qux7"
+                        }
+                      ]
+                    }
+                  }
+                ]
+              },
+              "init": {
+                "type": "Identifier",
+                "start": 518,
+                "end": 521,
+                "loc": {
+                  "start": {
+                    "line": 12,
+                    "column": 36
+                  },
+                  "end": {
+                    "line": 12,
+                    "column": 39
+                  }
+                },
+                "name": "bar"
+              }
+            }
+          ],
+          "kind": "const"
+        }
       }
     ],
     "directives": []