From d0f5ffa8e3f76a4c819059418e2d5f9f6d35e901 Mon Sep 17 00:00:00 2001
From: Vignesh Shanmugam <vignesh.shanmugam22@gmail.com>
Date: Tue, 8 May 2018 21:38:25 +0200
Subject: [PATCH 1/2] fix(deadcode): account for impure paths inside for
 statements

---
 .../__tests__/fixtures/loops/actual.js                     | 4 ++++
 .../__tests__/fixtures/loops/expected.js                   | 2 ++
 .../babel-plugin-minify-dead-code-elimination/src/index.js | 7 ++++++-
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/packages/babel-plugin-minify-dead-code-elimination/__tests__/fixtures/loops/actual.js b/packages/babel-plugin-minify-dead-code-elimination/__tests__/fixtures/loops/actual.js
index 89d57fdd2..bcf4a24eb 100644
--- a/packages/babel-plugin-minify-dead-code-elimination/__tests__/fixtures/loops/actual.js
+++ b/packages/babel-plugin-minify-dead-code-elimination/__tests__/fixtures/loops/actual.js
@@ -19,6 +19,10 @@ for (; true; ) {
 for (; false; ) {
   baz();
 }
+for (var j; false; ) {
+  blah();
+}
+for (0; false; ) {}
 
 // do_while
 do {
diff --git a/packages/babel-plugin-minify-dead-code-elimination/__tests__/fixtures/loops/expected.js b/packages/babel-plugin-minify-dead-code-elimination/__tests__/fixtures/loops/expected.js
index 4e95ee2bf..421553525 100644
--- a/packages/babel-plugin-minify-dead-code-elimination/__tests__/fixtures/loops/expected.js
+++ b/packages/babel-plugin-minify-dead-code-elimination/__tests__/fixtures/loops/expected.js
@@ -16,6 +16,8 @@ for (;;) {
   bar();
 }
 
+var j;
+
 // do_while
 do {
   foo();
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 448fa7d18..7f2f6f673 100644
--- a/packages/babel-plugin-minify-dead-code-elimination/src/index.js
+++ b/packages/babel-plugin-minify-dead-code-elimination/src/index.js
@@ -678,7 +678,12 @@ module.exports = ({ types: t, traverse }) => {
         if (result.value) {
           test.remove();
         } else {
-          path.remove();
+          const init = path.get("init");
+          if (init.node && !init.isPure()) {
+            path.replaceWith(init);
+          } else {
+            path.remove();
+          }
         }
       }
     },

From f6b1a9a20e81662122dde70f3e131099542b207a Mon Sep 17 00:00:00 2001
From: Vignesh Shanmugam <vignesh.shanmugam22@gmail.com>
Date: Tue, 8 May 2018 21:44:09 +0200
Subject: [PATCH 2/2] add env test

---
 .../__tests__/minify-env-tests.js                   | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/packages/babel-preset-minify/__tests__/minify-env-tests.js b/packages/babel-preset-minify/__tests__/minify-env-tests.js
index 55f7d1ce7..b175e8b61 100644
--- a/packages/babel-preset-minify/__tests__/minify-env-tests.js
+++ b/packages/babel-preset-minify/__tests__/minify-env-tests.js
@@ -183,4 +183,17 @@ describe("preset along with env", () => {
     })();
   `
   );
+
+  thePlugin(
+    "should fix issue#824 simplify + deadcode",
+    `
+      let foo;
+      while (0) {}
+      console.log(foo);
+    `,
+    `
+      var foo;
+      console.log(foo);
+    `
+  );
 });