fix corner cases in `collapse_vars`, `unused` & `varify` (#4292)

fixes #4290

1 files changed, 37 insertions, 0 deletions

diff --git a/test/compress/varify.js b/test/compress/varify.js
index d4894d2d..95acd032 100644
--- a/test/compress/varify.js
+++ b/test/compress/varify.js
@@ -353,3 +353,40 @@ forin_let_2: {
     ]
     node_version: ">=6"
 }
+
+issue_4290_1_const: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        varify: true,
+    }
+    input: {
+        const a = 0;
+        var a;
+    }
+    expect: {
+        const a = 0;
+        var a;
+    }
+    expect_stdout: true
+}
+
+issue_4290_1_let: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        varify: true,
+    }
+    input: {
+        "use strict";
+        let a = 0;
+        var a;
+    }
+    expect: {
+        "use strict";
+        let a = 0;
+        var a;
+    }
+    expect_stdout: true
+    node_version: ">=4"
+}