optimise rest parameters in spread element position and allocate rest array at the earliest common ancestor of all references - fixes #1768

test/core/fixtures/transformation/es6.parameters.rest/arrow-functions/actual.js

@@ -12,7 +12,6 @@ var somefun = function () {
     let somefg = (c, d, e, f, ...args3) => {
       var _a = args3[0];
     };
-    var _c = arguments[1];
     var _d = args1[1];
   };
   let get1stArg = (...args) => args[0];

test/core/fixtures/transformation/es6.parameters.rest/arrow-functions/expected.js

@@ -6,22 +6,15 @@ var concat = function concat() {
 };
 
 var somefun = function somefun() {
-  var _arguments = arguments;
-
   var get2ndArg = function get2ndArg(a, b) {
-    for (var _len = arguments.length, args1 = Array(_len > 2 ? _len - 2 : 0), _key = 2; _key < _len; _key++) {
-      args1[_key - 2] = arguments[_key];
-    }
-
-    var _b = args1[0];
+    var _b = arguments[2];
     var somef = function somef(x, y, z) {
       var _a = arguments[3];
     };
     var somefg = function somefg(c, d, e, f) {
       var _a = arguments[4];
     };
-    var _c = _arguments[1];
-    var _d = args1[1];
+    var _d = arguments[3];
   };
   var get1stArg = function get1stArg() {
     return arguments[0];
@@ -29,8 +22,8 @@ var somefun = function somefun() {
 };
 
 function demo1() {
-  for (var _len2 = arguments.length, args = Array(_len2), _key2 = 0; _key2 < _len2; _key2++) {
-    args[_key2] = arguments[_key2];
+  for (var _len = arguments.length, args = Array(_len), _key = 0; _key < _len; _key++) {
+    args[_key] = arguments[_key];
   }
 
   return function (i) {

test/core/fixtures/transformation/es6.parameters.rest/deepest-common-ancestor-earliest-child/actual.js

@@ -0,0 +1,32 @@
+// single referenes
+function r(...rest){
+  if (noNeedToWork) return 0;
+  return rest;
+}
+
+// multiple references
+function r(...rest){
+  if (noNeedToWork) return 0;
+
+  rest;
+  rest;
+}
+
+// multiple nested references
+function r(...rest){
+  if (noNeedToWork) return 0;
+
+  if (true) {
+    return rest;
+  } else {
+    return rest;
+  }
+}
+
+// nested reference with root reference
+function r(...rest){
+  if (noNeedToWork) return 0;
+
+  if (lol) rest;
+  rest;
+}

test/core/fixtures/transformation/es6.parameters.rest/deepest-common-ancestor-earliest-child/expected.js

@@ -0,0 +1,51 @@
+// single referenes
+"use strict";
+
+function r() {
+  if (noNeedToWork) return 0;
+
+  for (var _len = arguments.length, rest = Array(_len), _key = 0; _key < _len; _key++) {
+    rest[_key] = arguments[_key];
+  }
+
+  return rest;
+}
+
+// multiple references
+function r() {
+  if (noNeedToWork) return 0;
+
+  for (var _len2 = arguments.length, rest = Array(_len2), _key2 = 0; _key2 < _len2; _key2++) {
+    rest[_key2] = arguments[_key2];
+  }
+
+  rest;
+  rest;
+}
+
+// multiple nested references
+function r() {
+  if (noNeedToWork) return 0;
+
+  for (var _len3 = arguments.length, rest = Array(_len3), _key3 = 0; _key3 < _len3; _key3++) {
+    rest[_key3] = arguments[_key3];
+  }
+
+  if (true) {
+    return rest;
+  } else {
+    return rest;
+  }
+}
+
+// nested reference with root reference
+function r() {
+  if (noNeedToWork) return 0;
+
+  for (var _len4 = arguments.length, rest = Array(_len4), _key4 = 0; _key4 < _len4; _key4++) {
+    rest[_key4] = arguments[_key4];
+  }
+
+  if (lol) rest;
+  rest;
+}

test/core/fixtures/transformation/es6.parameters.rest/member-expression-deoptimisation/expected.js

@@ -47,10 +47,11 @@ var a = function a(foo) {
 };
 
 var b = function b(foo) {
+  var join = "join";
+
   for (var _len6 = arguments.length, bar = Array(_len6 > 1 ? _len6 - 1 : 0), _key6 = 1; _key6 < _len6; _key6++) {
     bar[_key6 - 1] = arguments[_key6];
   }
 
-  var join = "join";
   return bar[join];
-};
+};

test/core/fixtures/transformation/es6.parameters.rest/spread-optimisation/actual.js

@@ -0,0 +1,15 @@
+// optimisation
+
+function foo(...bar) {
+  foo(...bar);
+}
+
+// deoptimisation
+
+function foo(a, ...b) {
+  foo(...b);
+}
+
+function foo(...b) {
+  foo(1, ...b);
+}

test/core/fixtures/transformation/es6.parameters.rest/spread-optimisation/expected.js

@@ -0,0 +1,25 @@
+// optimisation
+
+"use strict";
+
+function foo() {
+  foo.apply(undefined, arguments);
+}
+
+// deoptimisation
+
+function foo(a) {
+  for (var _len = arguments.length, b = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
+    b[_key - 1] = arguments[_key];
+  }
+
+  foo.apply(undefined, b);
+}
+
+function foo() {
+  for (var _len2 = arguments.length, b = Array(_len2), _key2 = 0; _key2 < _len2; _key2++) {
+    b[_key2] = arguments[_key2];
+  }
+
+  foo.apply(undefined, [1].concat(b));
+}