From 8c3aab9a26d4ec68dc4945cd7f136c0566679802 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sat, 6 Jun 2015 03:33:32 +0100
Subject: [PATCH] add support for async functions to type inferrence

---
 src/babel/traversal/path/resolution.js | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/babel/traversal/path/resolution.js b/src/babel/traversal/path/resolution.js
index 70f8dfd4dc..c95c6a6887 100644
--- a/src/babel/traversal/path/resolution.js
+++ b/src/babel/traversal/path/resolution.js
@@ -272,7 +272,17 @@ export function _inferTypeAnnotation(force?: boolean): ?Object {
   if (callPath) {
     var callee = callPath.resolve();
     // todo: read typescript/flow interfaces
-    if (callee.isNodeType("Function")) return callee.node.returnType;
+    if (callee.isNodeType("Function")) {
+      if (callee.is("async")) {
+        if (callee.is("generator")) {
+          // todo
+        } else {
+          return t.genericTypeAnnotation(t.identifier("Promise"));
+        }
+      } else {
+        return callee.node.returnType;
+      }
+    }
   }
 }