Add static errors for object rest (#149)

* Fix parsing object rest

This makes object-rest-spread behave according to spec and only
allow one rest operator and enforces it to be the last
param in the object.

Also move all object-rest-spread tests to a own folder.

* Show nicer error messages

src/parser/expression.js

@@ -691,6 +691,8 @@ pp.parseObj = function (isPattern, refShorthandDefaultPos) {
   node.properties = [];
   this.next();
 
+  let firstRestLocation = null;
+
   while (!this.eat(tt.braceR)) {
     if (first) {
       first = false;
@@ -713,7 +715,21 @@ pp.parseObj = function (isPattern, refShorthandDefaultPos) {
       prop = this.parseSpread();
       prop.type = isPattern ? "RestProperty" : "SpreadProperty";
       node.properties.push(prop);
-      continue;
+      if (isPattern) {
+        const position = this.state.start;
+        if (firstRestLocation !== null) {
+          this.unexpected(firstRestLocation, "Cannot have multiple rest elements when destructuring");
+        } else if (this.eat(tt.braceR)) {
+          break;
+        } else if (this.match(tt.comma) && this.lookahead().type === tt.braceR) {
+          this.unexpected(position, "A trailing comma is not permitted after the rest element");
+        } else {
+          firstRestLocation = position;
+          continue;
+        }
+      } else {
+        continue;
+      }
     }
 
     prop.method = false;
@@ -753,6 +769,10 @@ pp.parseObj = function (isPattern, refShorthandDefaultPos) {
     node.properties.push(prop);
   }
 
+  if (firstRestLocation !== null) {
+    this.unexpected(firstRestLocation, "The rest element has to be the last element when destructuring");
+  }
+
   if (decorators.length) {
     this.raise(this.state.start, "You have trailing decorators with no property");
   }

test/fixtures/experimental/object-rest-spread/10/actual.js

@@ -0,0 +1 @@
+let { x, y, } = obj;

test/fixtures/experimental/object-rest-spread/10/expected.json

@@ -0,0 +1,211 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 20,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 20
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 20,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 1,
+        "column": 20
+      }
+    },
+    "sourceType": "script",
+    "body": [
+      {
+        "type": "VariableDeclaration",
+        "start": 0,
+        "end": 20,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 20
+          }
+        },
+        "declarations": [
+          {
+            "type": "VariableDeclarator",
+            "start": 4,
+            "end": 19,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 4
+              },
+              "end": {
+                "line": 1,
+                "column": 19
+              }
+            },
+            "id": {
+              "type": "ObjectPattern",
+              "start": 4,
+              "end": 13,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 4
+                },
+                "end": {
+                  "line": 1,
+                  "column": 13
+                }
+              },
+              "properties": [
+                {
+                  "type": "ObjectProperty",
+                  "start": 6,
+                  "end": 7,
+                  "loc": {
+                    "start": {
+                      "line": 1,
+                      "column": 6
+                    },
+                    "end": {
+                      "line": 1,
+                      "column": 7
+                    }
+                  },
+                  "method": false,
+                  "shorthand": true,
+                  "computed": false,
+                  "key": {
+                    "type": "Identifier",
+                    "start": 6,
+                    "end": 7,
+                    "loc": {
+                      "start": {
+                        "line": 1,
+                        "column": 6
+                      },
+                      "end": {
+                        "line": 1,
+                        "column": 7
+                      },
+                      "identifierName": "x"
+                    },
+                    "name": "x"
+                  },
+                  "value": {
+                    "type": "Identifier",
+                    "start": 6,
+                    "end": 7,
+                    "loc": {
+                      "start": {
+                        "line": 1,
+                        "column": 6
+                      },
+                      "end": {
+                        "line": 1,
+                        "column": 7
+                      },
+                      "identifierName": "x"
+                    },
+                    "name": "x"
+                  },
+                  "extra": {
+                    "shorthand": true
+                  }
+                },
+                {
+                  "type": "ObjectProperty",
+                  "start": 9,
+                  "end": 10,
+                  "loc": {
+                    "start": {
+                      "line": 1,
+                      "column": 9
+                    },
+                    "end": {
+                      "line": 1,
+                      "column": 10
+                    }
+                  },
+                  "method": false,
+                  "shorthand": true,
+                  "computed": false,
+                  "key": {
+                    "type": "Identifier",
+                    "start": 9,
+                    "end": 10,
+                    "loc": {
+                      "start": {
+                        "line": 1,
+                        "column": 9
+                      },
+                      "end": {
+                        "line": 1,
+                        "column": 10
+                      },
+                      "identifierName": "y"
+                    },
+                    "name": "y"
+                  },
+                  "value": {
+                    "type": "Identifier",
+                    "start": 9,
+                    "end": 10,
+                    "loc": {
+                      "start": {
+                        "line": 1,
+                        "column": 9
+                      },
+                      "end": {
+                        "line": 1,
+                        "column": 10
+                      },
+                      "identifierName": "y"
+                    },
+                    "name": "y"
+                  },
+                  "extra": {
+                    "shorthand": true
+                  }
+                }
+              ]
+            },
+            "init": {
+              "type": "Identifier",
+              "start": 16,
+              "end": 19,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 16
+                },
+                "end": {
+                  "line": 1,
+                  "column": 19
+                },
+                "identifierName": "obj"
+              },
+              "name": "obj"
+            }
+          }
+        ],
+        "kind": "let"
+      }
+    ],
+    "directives": []
+  }
+}

test/fixtures/experimental/object-rest-spread/6/actual.js

@@ -0,0 +1 @@
+({x, ...y, a, ...b, c, })

test/fixtures/experimental/object-rest-spread/6/expected.json

@@ -1,7 +1,7 @@
 {
   "type": "File",
   "start": 0,
-  "end": 23,
+  "end": 25,
   "loc": {
     "start": {
       "line": 1,
@@ -9,13 +9,13 @@
     },
     "end": {
       "line": 1,
-      "column": 23
+      "column": 25
     }
   },
   "program": {
     "type": "Program",
     "start": 0,
-    "end": 23,
+    "end": 25,
     "loc": {
       "start": {
         "line": 1,
@@ -23,7 +23,7 @@
       },
       "end": {
         "line": 1,
-        "column": 23
+        "column": 25
       }
     },
     "sourceType": "script",
@@ -31,7 +31,7 @@
       {
         "type": "ExpressionStatement",
         "start": 0,
-        "end": 23,
+        "end": 25,
         "loc": {
           "start": {
             "line": 1,
@@ -39,13 +39,13 @@
           },
           "end": {
             "line": 1,
-            "column": 23
+            "column": 25
           }
         },
         "expression": {
           "type": "ObjectExpression",
           "start": 1,
-          "end": 22,
+          "end": 24,
           "loc": {
             "start": {
               "line": 1,
@@ -53,7 +53,7 @@
             },
             "end": {
               "line": 1,
-              "column": 22
+              "column": 24
             }
           },
           "properties": [
@@ -86,7 +86,8 @@
                   "end": {
                     "line": 1,
                     "column": 3
-                  }
+                  },
+                  "identifierName": "x"
                 },
                 "name": "x"
               },
@@ -102,9 +103,13 @@
                   "end": {
                     "line": 1,
                     "column": 3
-                  }
+                  },
+                  "identifierName": "x"
                 },
                 "name": "x"
+              },
+              "extra": {
+                "shorthand": true
               }
             },
             {
@@ -133,7 +138,8 @@
                   "end": {
                     "line": 1,
                     "column": 9
-                  }
+                  },
+                  "identifierName": "y"
                 },
                 "name": "y"
               }
@@ -167,7 +173,8 @@
                   "end": {
                     "line": 1,
                     "column": 12
-                  }
+                  },
+                  "identifierName": "a"
                 },
                 "name": "a"
               },
@@ -183,9 +190,13 @@
                   "end": {
                     "line": 1,
                     "column": 12
-                  }
+                  },
+                  "identifierName": "a"
                 },
                 "name": "a"
+              },
+              "extra": {
+                "shorthand": true
               }
             },
             {
@@ -214,7 +225,8 @@
                   "end": {
                     "line": 1,
                     "column": 18
-                  }
+                  },
+                  "identifierName": "b"
                 },
                 "name": "b"
               }
@@ -248,7 +260,8 @@
                   "end": {
                     "line": 1,
                     "column": 21
-                  }
+                  },
+                  "identifierName": "c"
                 },
                 "name": "c"
               },
@@ -264,14 +277,19 @@
                   "end": {
                     "line": 1,
                     "column": 21
-                  }
+                  },
+                  "identifierName": "c"
                 },
                 "name": "c"
+              },
+              "extra": {
+                "shorthand": true
               }
             }
           ],
           "extra": {
-            "parenthesized": true
+            "parenthesized": true,
+            "parenStart": 0
           }
         }
       }

test/fixtures/experimental/object-rest-spread/7/actual.js

@@ -0,0 +1 @@
+let { ...x, y, z } = obj;

test/fixtures/experimental/object-rest-spread/7/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "The rest element has to be the last element when destructuring (1:10)"
+}

test/fixtures/experimental/object-rest-spread/8/actual.js

@@ -0,0 +1 @@
+let { x, y, ...z, } = obj;

test/fixtures/experimental/object-rest-spread/8/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "A trailing comma is not permitted after the rest element (1:16)"
+}

test/fixtures/experimental/object-rest-spread/9/actual.js

@@ -0,0 +1 @@
+let { x, ...y, ...z } = obj;

test/fixtures/experimental/object-rest-spread/9/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Cannot have multiple rest elements when destructuring (1:13)"
+}

test/fixtures/experimental/uncategorised/11/options.json

@@ -1,3 +0,0 @@
-{
-  "plugins": ["objectRestSpread"]
-}

test/fixtures/experimental/uncategorised/12/options.json

@@ -1,3 +0,0 @@
-{
-  "plugins": ["objectRestSpread"]
-}

test/fixtures/experimental/uncategorised/13/options.json

@@ -1,3 +0,0 @@
-{
-  "plugins": ["objectRestSpread"]
-}

test/fixtures/experimental/uncategorised/14/actual.js

@@ -1 +0,0 @@
-({x, ...y, a, ...b, c})

test/fixtures/experimental/uncategorised/14/options.json

@@ -1,3 +0,0 @@
-{
-  "plugins": ["objectRestSpread"]
-}

test/fixtures/experimental/uncategorised/9/options.json

@@ -1,3 +0,0 @@
-{
-  "plugins": ["objectRestSpread"]
-}