fix corner case in `collapse_vars` (#3574)

fixes #3573

1 files changed, 33 insertions, 0 deletions

diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index cf4e45a5..86e8d632 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -6435,3 +6435,36 @@ call_assign_order: {
     }
     expect_stdout: "PASS PASS"
 }
+
+issue_3573: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var c = 0;
+        (function(b) {
+            while (--b) {
+                b = NaN;
+                switch (0 / this < 0) {
+                  case c++, false:
+                  case c++, NaN:
+                }
+            }
+        })(3);
+        console.log(c);
+    }
+    expect: {
+        var c = 0;
+        (function(b) {
+            while (--b) {
+                b = NaN;
+                switch (0 / this < 0) {
+                  case c++, false:
+                  case c++, NaN:
+                }
+            }
+        })(3);
+        console.log(c);
+    }
+    expect_stdout: "1"
+}