Fix arrow transformation when arguments is defined as variable (#12344)

* fix: arrow-fn transformation when 'arguments' is defined as var

* fix: tests

* refactor: code

* Review by @nicolo-ribaudo

Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com>

packages/babel-plugin-transform-arrow-functions/test/fixtures/arrow-functions/arguments-global-undeclared/input.js

@@ -0,0 +1,9 @@
+function fn() {
+  var foo = () => {
+    return arguments;
+  };
+}
+
+var bar = () => arguments;
+
+var baz = () => () => arguments;

packages/babel-plugin-transform-arrow-functions/test/fixtures/arrow-functions/arguments-global-undeclared/output.js

@@ -0,0 +1,19 @@
+var _arguments2 = typeof arguments === "undefined" ? void 0 : arguments;
+
+function fn() {
+  var _arguments = arguments;
+
+  var foo = function () {
+    return _arguments;
+  };
+}
+
+var bar = function () {
+  return _arguments2;
+};
+
+var baz = function () {
+  return function () {
+    return _arguments2;
+  };
+};

packages/babel-plugin-transform-arrow-functions/test/fixtures/arrow-functions/arguments-global-var/input.js

@@ -0,0 +1,10 @@
+var arguments = 1;
+function fn() {
+  var foo = () => {
+    return arguments;
+  };
+}
+
+var bar = () => arguments;
+
+var baz = () => () => arguments;

packages/babel-plugin-transform-arrow-functions/test/fixtures/arrow-functions/arguments-global-var/output.js

@@ -0,0 +1,19 @@
+var _arguments2 = 1;
+
+function fn() {
+  var _arguments = _arguments2;
+
+  var foo = function () {
+    return _arguments;
+  };
+}
+
+var bar = function () {
+  return _arguments2;
+};
+
+var baz = function () {
+  return function () {
+    return _arguments2;
+  };
+};

packages/babel-plugin-transform-arrow-functions/test/fixtures/arrow-functions/arguments/input.js

@@ -43,3 +43,39 @@ function six(obj) {
   return fn();
 }
 six();
+
+var seven = () => {
+    var arguments = 1;
+    return arguments;
+};
+seven();
+
+var eight = () => {
+    var arguments = 1;
+    return () => arguments;
+};
+eight();
+
+function nine() {
+    var arguments = 1;
+    var foo = () => {
+      return arguments;
+    };
+}
+nine();
+
+var eleven = () => {
+  var arguments = 2;
+  return function () {
+    return () => arguments;
+  }
+};
+eleven()(1,2,3)();
+
+var twelve = () => {
+  var arguments = 2;
+  return class {
+    m() { return () => arguments; }
+  }
+};
+twelve();

packages/babel-plugin-transform-arrow-functions/test/fixtures/arrow-functions/arguments/output.js

@@ -81,3 +81,56 @@ function six(obj) {
 }
 
 six();
+
+var seven = function () {
+  var _arguments6 = 1;
+  return _arguments6;
+};
+
+seven();
+
+var eight = function () {
+  var _arguments7 = 1;
+  return function () {
+    return _arguments7;
+  };
+};
+
+eight();
+
+function nine() {
+  var _arguments8 = 1;
+
+  var foo = function () {
+    return _arguments8;
+  };
+}
+
+nine();
+
+var eleven = function () {
+  var arguments = 2;
+  return function () {
+    var _arguments9 = arguments;
+    return function () {
+      return _arguments9;
+    };
+  };
+};
+
+eleven()(1, 2, 3)();
+
+var twelve = function () {
+  var arguments = 2;
+  return class {
+    m() {
+      var _arguments10 = arguments;
+      return function () {
+        return _arguments10;
+      };
+    }
+
+  };
+};
+
+twelve();