From 7e020272c11a15fe86a1fc90087c6914a829cbd3 Mon Sep 17 00:00:00 2001
From: Boopathi Rajaa <boopathi@users.noreply.github.com>
Date: Mon, 21 Nov 2016 04:44:56 +0100
Subject: [PATCH] Fix path.evaluate for references before declarations (#4875)

---
 packages/babel-traverse/src/path/evaluation.js |  4 ++++
 packages/babel-traverse/test/evaluation.js     | 12 ++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/packages/babel-traverse/src/path/evaluation.js b/packages/babel-traverse/src/path/evaluation.js
index ef478103b1fb..3b41b188c6ce 100644
--- a/packages/babel-traverse/src/path/evaluation.js
+++ b/packages/babel-traverse/src/path/evaluation.js
@@ -173,6 +173,10 @@ export function evaluate(): { confident: boolean; value: any } {
         return deopt(binding.path);
       }
 
+      if (binding && path.node.start < binding.path.node.end) {
+        return deopt(binding.path);
+      }
+
       if (binding && binding.hasValue) {
         return binding.value;
       } else {
diff --git a/packages/babel-traverse/test/evaluation.js b/packages/babel-traverse/test/evaluation.js
index 97dc0c3df9dd..956d656eb3d3 100644
--- a/packages/babel-traverse/test/evaluation.js
+++ b/packages/babel-traverse/test/evaluation.js
@@ -86,4 +86,16 @@ describe("evaluation", function () {
       false
     );
   });
+
+  it("should deopt ids that are referenced before the bindings", function () {
+    assert.strictEqual(
+      getPath("let x = y + 5; let y = 5;").get("body.0.declarations.0.init").evaluate().confident,
+      false
+    );
+    assert.strictEqual(
+      getPath("if (typeof x === 'undefined') var x = {}")
+        .get("body.0.test").evaluate().confident,
+      false
+    );
+  });
 });