Add "allowArrayLike" opt to destructuring and spread transforms (#11265)

packages/babel-plugin-transform-destructuring/src/index.js

@@ -4,7 +4,11 @@ import { types as t } from "@babel/core";
 export default declare((api, options) => {
   api.assertVersion(7);
 
-  const { loose = false, useBuiltIns = false } = options;
+  const {
+    loose = false,
+    useBuiltIns = false,
+    allowArrayLike = false,
+  } = options;
 
   if (typeof loose !== "boolean") {
     throw new Error(`.loose must be a boolean or undefined`);
@@ -85,6 +89,7 @@ export default declare((api, options) => {
       this.scope = opts.scope;
       this.kind = opts.kind;
       this.arrayOnlySpread = opts.arrayOnlySpread;
+      this.allowArrayLike = opts.allowArrayLike;
       this.addHelper = opts.addHelper;
     }
 
@@ -141,7 +146,7 @@ export default declare((api, options) => {
       ) {
         return node;
       } else {
-        return this.scope.toArray(node, count);
+        return this.scope.toArray(node, count, this.allowArrayLike);
       }
     }
 
@@ -523,6 +528,7 @@ export default declare((api, options) => {
           scope: scope,
           nodes: nodes,
           arrayOnlySpread,
+          allowArrayLike,
           addHelper: name => this.addHelper(name),
         });
 
@@ -548,6 +554,7 @@ export default declare((api, options) => {
           scope: scope,
           nodes: nodes,
           arrayOnlySpread,
+          allowArrayLike,
           addHelper: name => this.addHelper(name),
         });
         destructuring.init(pattern, ref);
@@ -566,6 +573,7 @@ export default declare((api, options) => {
           scope: scope,
           nodes: nodes,
           arrayOnlySpread,
+          allowArrayLike,
           addHelper: name => this.addHelper(name),
         });
 
@@ -624,6 +632,7 @@ export default declare((api, options) => {
             scope: scope,
             kind: node.kind,
             arrayOnlySpread,
+            allowArrayLike,
             addHelper: name => this.addHelper(name),
           });
 

packages/babel-plugin-transform-destructuring/test/fixtures/allowArrayLike/holes/exec.js

@@ -0,0 +1,6 @@
+var o = { 0: "a", 2: "c", length: 3 };
+
+var [...rest] = o;
+
+expect(rest).toEqual(["a", undefined, "c"]);
+expect(1 in rest).toBe(true); // Not holey

packages/babel-plugin-transform-destructuring/test/fixtures/allowArrayLike/holes/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    ["external-helpers", { "helperVersion": "7.100.0" }],
+    ["transform-destructuring", { "allowArrayLike": true }]
+  ]
+}

packages/babel-plugin-transform-destructuring/test/fixtures/allowArrayLike/length-cropped/exec.js

@@ -0,0 +1,6 @@
+var o = { 0: "a", 1: "b", 2: "c", length: 2 };
+
+var [first, ...rest] = o;
+
+expect(first).toBe("a");
+expect(rest).toEqual(["b"]);

packages/babel-plugin-transform-destructuring/test/fixtures/allowArrayLike/length-cropped/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    ["external-helpers", { "helperVersion": "7.100.0" }],
+    ["transform-destructuring", { "allowArrayLike": true }]
+  ]
+}

packages/babel-plugin-transform-destructuring/test/fixtures/allowArrayLike/simple/exec.js

@@ -0,0 +1,6 @@
+var o = { 0: "a", 1: "b", 2: "c", length: 3 };
+
+var [first, ...rest] = o;
+
+expect(first).toBe("a");
+expect(rest).toEqual(["b", "c"]);

packages/babel-plugin-transform-destructuring/test/fixtures/allowArrayLike/simple/input.js

@@ -0,0 +1 @@
+var [first, ...rest] = o;

packages/babel-plugin-transform-destructuring/test/fixtures/allowArrayLike/simple/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    ["external-helpers", { "helperVersion": "7.100.0" }],
+    ["transform-destructuring", { "allowArrayLike": true }]
+  ]
+}

packages/babel-plugin-transform-destructuring/test/fixtures/allowArrayLike/simple/output.js

@@ -0,0 +1,4 @@
+var _o = o,
+    _o2 = babelHelpers.maybeArrayLike(babelHelpers.toArray, _o),
+    first = _o2[0],
+    rest = _o2.slice(1);