Remove unused bindings when excluding keys with rest in loose mode (#8264)

packages/babel-plugin-proposal-object-rest-spread/src/index.js

@@ -92,6 +92,17 @@ export default declare((api, opts) => {
     return impureComputedPropertyDeclarators;
   }
 
+  function removeUnusedExcludedKeys(path) {
+    const bindings = path.getOuterBindingIdentifierPaths();
+
+    Object.keys(bindings).forEach(bindingName => {
+      if (path.scope.getBinding(bindingName).references > 1) {
+        return;
+      }
+      bindings[bindingName].parentPath.remove();
+    });
+  }
+
   //expects path to an object pattern
   function createObjectSpread(path, file, objRef) {
     const props = path.get("properties");
@@ -241,12 +252,17 @@ export default declare((api, opts) => {
           const objectPatternPath = path.findParent(path =>
             path.isObjectPattern(),
           );
+
           const [
             impureComputedPropertyDeclarators,
             argument,
             callExpression,
           ] = createObjectSpread(objectPatternPath, file, ref);
 
+          if (loose) {
+            removeUnusedExcludedKeys(objectPatternPath);
+          }
+
           t.assertIdentifier(argument);
 
           insertionPath.insertBefore(impureComputedPropertyDeclarators);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/remove-unused-excluded-keys-loose/input.js

@@ -0,0 +1,22 @@
+// should not remove when destructuring into existing bindings
+({ a2, ...b2 } = c2);
+
+class Comp extends React.Component {
+  render() {
+    const {
+      excluded,
+      excluded2: excludedRenamed,
+      used,
+      used2: usedRenamed,
+      ...props
+    } = this.props;
+
+    console.log(used, usedRenamed);
+
+    return React.createElement("input", props);
+  }
+}
+
+function smth({ unused, ...rest }) {
+  call(rest);
+}

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/remove-unused-excluded-keys-loose/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    "external-helpers",
+    ["proposal-object-rest-spread", { "loose": true }]
+  ]
+}

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/remove-unused-excluded-keys-loose/output.js

@@ -0,0 +1,26 @@
+// should not remove when destructuring into existing bindings
+var _c = c2;
+({
+  a2
+} = _c);
+b2 = babelHelpers.objectWithoutProperties(_c, ["a2"]);
+_c;
+
+class Comp extends React.Component {
+  render() {
+    const _this$props = this.props,
+          {
+      used,
+      used2: usedRenamed
+    } = _this$props,
+          props = babelHelpers.objectWithoutProperties(_this$props, ["excluded", "excluded2", "used", "used2"]);
+    console.log(used, usedRenamed);
+    return React.createElement("input", props);
+  }
+
+}
+
+function smth(_ref) {
+  let rest = babelHelpers.objectWithoutProperties(_ref, ["unused"]);
+  call(rest);
+}