From 06958bc11e50038da9d1c03753d579e1da78c647 Mon Sep 17 00:00:00 2001
From: Boopathi Rajaa <me@boopathi.in>
Date: Tue, 11 Jul 2017 12:28:32 +0200
Subject: [PATCH 1/2] Detect duplicate declaration during one-use replacement

Fix #611
---
 .../__tests__/dead-code-elimination-test.js   | 14 ++++++++++++++
 .../src/index.js                              | 19 +++++++++++++++++--
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/packages/babel-plugin-minify-dead-code-elimination/__tests__/dead-code-elimination-test.js b/packages/babel-plugin-minify-dead-code-elimination/__tests__/dead-code-elimination-test.js
index 3e4476b64..abecf1de3 100644
--- a/packages/babel-plugin-minify-dead-code-elimination/__tests__/dead-code-elimination-test.js
+++ b/packages/babel-plugin-minify-dead-code-elimination/__tests__/dead-code-elimination-test.js
@@ -2448,4 +2448,18 @@ describe("dce-plugin", () => {
       }
     `
   );
+
+  thePlugin(
+    "should fix issue#611 - transforming fn decl to expr",
+    `
+      function foo() {
+        function count() {
+          let count = 1;
+          bar(count);
+          return count;
+        }
+        return count;
+      }
+    `
+  );
 });
diff --git a/packages/babel-plugin-minify-dead-code-elimination/src/index.js b/packages/babel-plugin-minify-dead-code-elimination/src/index.js
index 9f3bdbfc2..e01de55e5 100644
--- a/packages/babel-plugin-minify-dead-code-elimination/src/index.js
+++ b/packages/babel-plugin-minify-dead-code-elimination/src/index.js
@@ -400,7 +400,8 @@ module.exports = ({ types: t, traverse }) => {
               const replaced = replace(binding.referencePaths[0], {
                 binding,
                 scope,
-                replacement
+                replacement,
+                replacementPath
               });
 
               if (replaced) {
@@ -936,7 +937,7 @@ module.exports = ({ types: t, traverse }) => {
   }
 
   function replace(path, options) {
-    const { replacement, scope, binding } = options;
+    const { replacement, replacementPath, scope, binding } = options;
 
     // Same name, different binding.
     if (scope.getBinding(path.node.name) !== binding) {
@@ -976,6 +977,20 @@ module.exports = ({ types: t, traverse }) => {
       return;
     }
 
+    // https://github.com/babel/babili/issues/611
+    // this is valid only for FunctionDeclaration where we convert
+    // function declaration to expression in the next step
+    if (replacementPath.isFunctionDeclaration()) {
+      const id = replacementPath.get("id");
+      if (id.isIdentifier()) {
+        for (let name in replacementPath.scope.bindings) {
+          if (name === id.node.name) {
+            return;
+          }
+        }
+      }
+    }
+
     // https://github.com/babel/babili/issues/130
     if (!t.isExpression(replacement)) {
       t.toExpression(replacement);

From 58583b1a399aac71cbf6b06daa962d319ecce471 Mon Sep 17 00:00:00 2001
From: Boopathi Rajaa <me@boopathi.in>
Date: Tue, 11 Jul 2017 13:00:19 +0200
Subject: [PATCH 2/2] FnDecls always have id

---
 .../src/index.js                                       | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/packages/babel-plugin-minify-dead-code-elimination/src/index.js b/packages/babel-plugin-minify-dead-code-elimination/src/index.js
index e01de55e5..796c08787 100644
--- a/packages/babel-plugin-minify-dead-code-elimination/src/index.js
+++ b/packages/babel-plugin-minify-dead-code-elimination/src/index.js
@@ -981,12 +981,10 @@ module.exports = ({ types: t, traverse }) => {
     // this is valid only for FunctionDeclaration where we convert
     // function declaration to expression in the next step
     if (replacementPath.isFunctionDeclaration()) {
-      const id = replacementPath.get("id");
-      if (id.isIdentifier()) {
-        for (let name in replacementPath.scope.bindings) {
-          if (name === id.node.name) {
-            return;
-          }
+      const fnName = replacementPath.get("id").node.name;
+      for (let name in replacementPath.scope.bindings) {
+        if (name === fnName) {
+          return;
         }
       }
     }