From 953dd1df48b3009e3ff63bdddcb049a51f81457c Mon Sep 17 00:00:00 2001
From: Boopathi Rajaa <boopathi@users.noreply.github.com>
Date: Wed, 31 Aug 2016 23:01:59 +0200
Subject: [PATCH] Fix toExpression converting arrow functions to function
 expressions without block body (#3687)

---
 packages/babel-types/src/converters.js | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/packages/babel-types/src/converters.js b/packages/babel-types/src/converters.js
index f3ce679d84..dcfc14d9f9 100644
--- a/packages/babel-types/src/converters.js
+++ b/packages/babel-types/src/converters.js
@@ -204,17 +204,31 @@ export function toExpression(node: Object): Object {
     node = node.expression;
   }
 
+  // return unmodified node
+  // important for things like ArrowFunctions where
+  // type change from ArrowFunction to FunctionExpression
+  // produces bugs like -> `()=>a` to `function () a`
+  // without generating a BlockStatement for it
+  // ref: https://github.com/babel/babili/issues/130
+  if (t.isExpression(node)) {
+    return node;
+  }
+
+  // convert all classes and functions
+  // ClassDeclaration -> ClassExpression
+  // FunctionDeclaration, ObjectMethod, ClassMethod -> FunctionExpression
   if (t.isClass(node)) {
     node.type = "ClassExpression";
   } else if (t.isFunction(node)) {
     node.type = "FunctionExpression";
   }
 
-  if (t.isExpression(node)) {
-    return node;
-  } else {
+  // if it's still not an expression
+  if (!t.isExpression(node)) {
     throw new Error(`cannot turn ${node.type} to an expression`);
   }
+
+  return node;
 }
 
 export function toBlock(node: Object, parent: Object): Object {