rewrite named function expressions in async function transformers - fixes #979

src/babel/transformation/helpers/remap-async-to-generator.js

@@ -1,7 +1,7 @@
 import t from "../../types";
 
-var visitor = {
-  enter(node) {
+var awaitVisitor = {
+  enter(node, parent, scope, state) {
     if (t.isFunction(node)) this.skip();
 
     if (t.isAwaitExpression(node)) {
@@ -16,13 +16,23 @@ var visitor = {
   }
 };
 
+var referenceVisitor = {
+  enter(node, parent, scope, state) {
+    var name = state.id.name;
+    if (t.isReferencedIdentifier(node, parent, { name: name }) && scope.bindingIdentifierEquals(name, state.id)) {
+      return state.ref ||= scope.generateUidIdentifier(name);
+    }
+  }
+};
+
 export default function (node, callId, scope) {
   node.async = false;
   node.generator = true;
 
-  scope.traverse(node, visitor);
+  scope.traverse(node, awaitVisitor, state);
 
   var call = t.callExpression(callId, [node]);
+
   var id = node.id;
   node.id = null;
 
@@ -33,6 +43,16 @@ export default function (node, callId, scope) {
     declar._blockHoist = true;
     return declar;
   } else {
+    if (id) {
+      var state = { id: id };
+      scope.traverse(node, referenceVisitor, state);
+
+      if (state.ref) {
+        scope.parent.push({ id: state.ref });
+        return t.assignmentExpression("=", state.ref, call);
+      }
+    }
+
     return call;
   }
 };

src/babel/traversal/scope.js

@@ -583,7 +583,7 @@ export default class Scope {
 
     if (t.isBlockStatement(block) || t.isProgram(block)) {
       block._declarations ||= {};
-      block._declarations[opts.key] = {
+      block._declarations[opts.key || opts.id.name] = {
         kind: opts.kind || "var",
         id: opts.id,
         init: opts.init