log spread element rest parameter as a candidate instead of replacing it in place - fixes #1796

src/babel/transformation/transformers/es6/parameters.rest.js

@@ -42,7 +42,8 @@ var memberExpressionOptimisationVisitor = {
       if (this.parentPath.isSpreadElement() && state.offset === 0) {
         var call = this.parentPath.parentPath;
         if (call.isCallExpression() && call.node.arguments.length === 1) {
-          return state.argumentsNode;
+          state.candidates.push(this);
+          return;
         }
       }
     }
@@ -124,7 +125,9 @@ export var visitor = {
       if (state.candidates.length) {
         for (var candidate of (state.candidates: Array)) {
           candidate.replaceWith(argsId);
-          optimiseMemberExpression(candidate.parent, state.offset);
+          if (candidate.parentPath.isMemberExpression()) {
+            optimiseMemberExpression(candidate.parent, state.offset);
+          }
         }
       }
       return;

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

@@ -13,3 +13,8 @@ function foo(a, ...b) {
 function foo(...b) {
   foo(1, ...b);
 }
+
+function foo(...args){
+  args.pop()
+  foo(...args);
+}

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

@@ -23,3 +23,12 @@ function foo() {
 
   foo.apply(undefined, [1].concat(b));
 }
+
+function foo() {
+  for (var _len3 = arguments.length, args = Array(_len3), _key3 = 0; _key3 < _len3; _key3++) {
+    args[_key3] = arguments[_key3];
+  }
+
+  args.pop();
+  foo.apply(undefined, args);
+}