fix corner case in `reduce_vars` (#4585)

fixes #4584

2 files changed, 39 insertions, 6 deletions

diff --git a/test/compress/destructured.js b/test/compress/destructured.js
index 7cc6f46d..58fec606 100644
--- a/test/compress/destructured.js
+++ b/test/compress/destructured.js
@@ -2487,3 +2487,30 @@ issue_4554: {
     expect_stdout: "PASS"
     node_version: ">=6"
 }
+
+issue_4584: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        try {
+            (function f({
+                [console.log(a = "FAIL")]: a,
+            }) {})(0);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            (function f({
+                [console.log(a = "FAIL")]: a,
+            }) {})(0);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
diff --git a/test/ufuzz/index.js b/test/ufuzz/index.js
index a6784ee7..0a6de2a3 100644
--- a/test/ufuzz/index.js
+++ b/test/ufuzz/index.js
@@ -431,12 +431,18 @@ function createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, was
     unique_vars.length = len;
     return pairs;
 
-    function mapShuffled(array, fn) {
-        var result = [];
-        for (var i = array.length; --i >= 0;) {
-            result.splice(rng(result.length + 1), 0, fn(array[i], i));
-        }
-        return result;
+    function mapShuffled(values, fn) {
+        var ordered = [];
+        var shuffled = [];
+        values.forEach(function(value, index) {
+            value = fn(value, index);
+            if (/]:/.test(value) ? canThrow && rng(10) == 0 : rng(5)) {
+                shuffled.splice(rng(shuffled.length + 1), 0, value);
+            } else {
+                ordered.push(value);
+            }
+        });
+        return shuffled.concat(ordered);
     }
 
     function convertToRest(names) {