From 684c4e3b0649c08c64d8202f9165435570b42d36 Mon Sep 17 00:00:00 2001
From: alexlamsl <alexlamsl@gmail.com>
Date: Sat, 25 Mar 2017 19:54:45 +0800
Subject: [PATCH] fix `reduce_vars` on `AST_Switch` Take conditional nature of
 switch branches into account.

fixes #1670
---
 lib/compress.js              |   2 +-
 test/compress/reduce_vars.js | 118 +++++++++++++++++++++++++++++++++++
 2 files changed, 119 insertions(+), 1 deletion(-)

diff --git a/lib/compress.js b/lib/compress.js
index e12c5eb0..bea9c9a4 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -341,7 +341,7 @@ merge(Compressor.prototype, {
                     pop();
                     return true;
                 }
-                if (node instanceof AST_Catch) {
+                if (node instanceof AST_Catch || node instanceof AST_SwitchBranch) {
                     push();
                     descend();
                     pop();
diff --git a/test/compress/reduce_vars.js b/test/compress/reduce_vars.js
index 3d5612cf..b6717a93 100644
--- a/test/compress/reduce_vars.js
+++ b/test/compress/reduce_vars.js
@@ -1364,3 +1364,121 @@ issue_1606: {
         }
     }
 }
+
+issue_1670_1: {
+    options = {
+        comparisons: true,
+        conditionals: true,
+        evaluate: true,
+        dead_code: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function f() {
+            switch (1) {
+              case 0:
+                var a = true;
+                break;
+              default:
+                if (typeof a === "undefined") console.log("PASS");
+                else console.log("FAIL");
+            }
+        })();
+    }
+    expect: {
+        (function() {
+            var a;
+            void 0 === a ? console.log("PASS") : console.log("FAIL");
+        })();
+    }
+    expect_stdout: true
+}
+
+issue_1670_2: {
+    options = {
+        conditionals: true,
+        evaluate: true,
+        dead_code: true,
+        passes: 2,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function f() {
+            switch (1) {
+              case 0:
+                var a = true;
+                break;
+              default:
+                if (typeof a === "undefined") console.log("PASS");
+                else console.log("FAIL");
+            }
+        })();
+    }
+    expect: {
+        (function() {
+            console.log("PASS");
+        })();
+    }
+    expect_stdout: true
+}
+
+issue_1670_3: {
+    options = {
+        comparisons: true,
+        conditionals: true,
+        evaluate: true,
+        dead_code: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function f() {
+            switch (1) {
+              case 0:
+                var a = true;
+                break;
+              case 1:
+                if (typeof a === "undefined") console.log("PASS");
+                else console.log("FAIL");
+            }
+        })();
+    }
+    expect: {
+        (function() {
+            var a;
+            void 0 === a ? console.log("PASS") : console.log("FAIL");
+        })();
+    }
+    expect_stdout: true
+}
+
+issue_1670_4: {
+    options = {
+        conditionals: true,
+        evaluate: true,
+        dead_code: true,
+        passes: 2,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function f() {
+            switch (1) {
+              case 0:
+                var a = true;
+                break;
+              case 1:
+                if (typeof a === "undefined") console.log("PASS");
+                else console.log("FAIL");
+            }
+        })();
+    }
+    expect: {
+        (function() {
+            console.log("PASS");
+        })();
+    }
+    expect_stdout: true
+}