Define default value for vars shadowing params (#11307)

* Define default value for vars shadowing params

* Remove from package.json

* Only convert traverse the params if needed

This prevents this plugin from running after the destructuring
transform, which causes #11256

* Review

* Review

* Update packages/babel-plugin-transform-parameters/src/params.js [skip ci]

Co-Authored-By: Brian Ng <bng412@gmail.com>

Co-authored-by: Brian Ng <bng412@gmail.com>

packages/babel-plugin-transform-parameters/test/fixtures/parameters/fn-decl-same-as-param/output.js

@@ -1,6 +1,6 @@
 function foo() {
   var a = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : 2;
-  return function () {
+  return function (a) {
     function a() {}
-  }();
+  }(a);
 }

packages/babel-plugin-transform-parameters/test/fixtures/parameters/iife-this/output.js

@@ -10,11 +10,13 @@ var Test = /*#__PURE__*/function () {
   babelHelpers.createClass(Test, [{
     key: "invite",
     value: function invite() {
+      var _this = this;
+
       var p = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : a;
       return function () {
         var a;
-        this;
-      }.apply(this);
+        _this;
+      }();
     }
   }]);
   return Test;

packages/babel-plugin-transform-parameters/test/fixtures/parameters/var-no-init-for-init-same-as-param/exec.js

@@ -1,5 +1,5 @@
 function foo(a = 2) {
   for (var a, i = 0; i < 1; i++);
-  expect(a).toBe(undefined);
+  expect(a).toBe(2);
 }
 foo();

packages/babel-plugin-transform-parameters/test/fixtures/parameters/var-no-init-same-as-param/output.js

@@ -1,8 +1,8 @@
 function f() {
   var a = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : 2;
   var b = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 3;
-  return function () {
+  return function (b) {
     var b = 4;
     return a + b;
-  }();
+  }(b);
 }

packages/babel-plugin-transform-parameters/test/fixtures/parameters/var-no-init-then-var-with-init-same-as-param/output.js

@@ -1,11 +1,11 @@
 function f() {
   var a = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : 2;
   var b = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 3;
-  return function () {
+  return function (a) {
     var _a = {
       a: 4
     },
         a = _a.a;
     return a + b;
-  }();
+  }(a);
 }

packages/babel-plugin-transform-parameters/test/fixtures/parameters/var-same-as-array-pattern-param/output.js

@@ -1,9 +1,9 @@
 function foo(_ref) {
   var a = _ref.a,
       b = _ref.b;
-  return function () {
+  return function (a) {
     var a = 3;
     var c = 2;
     var d = a + b + c;
-  }();
+  }(a);
 }

packages/babel-plugin-transform-parameters/test/fixtures/parameters/var-same-as-object-pattern-param/output.js

@@ -3,9 +3,9 @@ function foo(_ref) {
       a = _ref2[0],
       b = _ref2[1];
 
-  return function () {
+  return function (a) {
     var a = 3;
     var c = 2;
     var d = a + b + c;
-  }();
+  }(a);
 }

packages/babel-plugin-transform-parameters/test/fixtures/parameters/var-same-as-param/output.js

@@ -1,6 +1,6 @@
 function foo() {
   var a = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : 2;
-  return function () {
+  return function (a) {
     var a = 1;
-  }();
+  }(a);
 }

packages/babel-plugin-transform-parameters/test/fixtures/parameters/var-with-init-then-var-no-init-same-as-param/output.js

@@ -1,11 +1,11 @@
 function f() {
   var a = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : 2;
   var b = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 3;
-  return function () {
+  return function (a) {
     var _a = {
       a: 4
     },
         a = _a.a;
     return a + b;
-  }();
+  }(a);
 }

packages/babel-plugin-transform-parameters/test/fixtures/regression/11231/output.mjs

@@ -1,6 +1,6 @@
 (function () {
   let i = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : "__proto__";
-  return function () {
+  return function (i) {
     for (var i in {});
-  }();
+  }(i);
 });

packages/babel-plugin-transform-parameters/test/fixtures/regression/11256/input.js

@@ -0,0 +1,7 @@
+class A {
+  a = b => {
+    {
+      ({ b } = {});
+    }
+  };
+}

packages/babel-plugin-transform-parameters/test/fixtures/regression/11256/options.json

@@ -0,0 +1,8 @@
+{
+  "plugins": [
+    "proposal-class-properties",
+    "transform-parameters",
+    "transform-destructuring",
+    ["external-helpers", { "helperVersion": "7.100.0" }]
+  ]
+}

packages/babel-plugin-transform-parameters/test/fixtures/regression/11256/output.js

@@ -0,0 +1,11 @@
+class A {
+  constructor() {
+    babelHelpers.defineProperty(this, "a", b => {
+      {
+        var _ref = {};
+        b = _ref.b;
+      }
+    });
+  }
+
+}

packages/babel-plugin-transform-parameters/test/fixtures/regression/11303/exec.js

@@ -0,0 +1,6 @@
+function test(a, b = 1) {
+  var a = a + b;
+  return a;
+}
+
+expect(test(2)).toBe(3);

packages/babel-plugin-transform-parameters/test/fixtures/regression/11303/input.js

@@ -0,0 +1,4 @@
+function test(a, b = 1) {
+  var a = a + b;
+  return a;
+}

packages/babel-plugin-transform-parameters/test/fixtures/regression/11303/options.json

@@ -0,0 +1,5 @@
+{
+  "plugins": [
+    "transform-parameters"
+  ]
+}

packages/babel-plugin-transform-parameters/test/fixtures/regression/11303/output.js

@@ -0,0 +1,7 @@
+function test(a) {
+  let b = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 1;
+  return function (a) {
+    var a = a + b;
+    return a;
+  }(a);
+}