Ensure switch branches reordering happens only for constant branch ex…

…pressions (#1092)
terser · Oct 19, 2021 · f251cd4 · f251cd4
1 parent 01f1841
commit f251cd4
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diff --git a/lib/compress/index.js b/lib/compress/index.js
@@ -1606,7 +1606,7 @@ def_optimize(AST_Switch, function(self, compressor) {
     // that way the next micro-optimization will merge them.
     // ** bail micro-optimization if not a simple switch case with breaks
     if (body.every((branch, i) =>
-        (branch === default_or_exact || !branch.expression.has_side_effects(compressor))
+        (branch === default_or_exact || branch.expression instanceof AST_Constant)
         && (branch.body.length === 0 || aborts(branch) || body.length - 1 === i))
     ) {
         for (let i = 0; i < body.length; i++) {

diff --git a/test/compress/switch.js b/test/compress/switch.js
@@ -2594,6 +2594,42 @@ collapse_same_branches_not_in_a_row_ensure_no_side_effects: {
     }
     expect_stdout: ["2"]
 }
+
+collapse_same_branches_not_in_a_row_ensure_no_evaluate_elad: {
+    options = {
+        switches: true,
+        dead_code: true
+    }
+    input: {
+        let i = 1;
+        switch (true) {
+            case 3 == i:
+                console.log(i);
+                break;
+            case 5 == i:
+                console.log(5);
+                break;
+            case 1 == i:
+                console.log(i);
+                break;
+        }
+    }
+    expect: {
+        let i = 1;
+        switch (true) {
+            case 3 == i:
+                console.log(i);
+                break;
+            case 5 == i:
+                console.log(5);
+                break;
+            case 1 == i:
+                console.log(i);
+        }
+    }
+    expect_stdout: ["1"]
+}
+
 collapse_same_branches_not_in_a_row_even_if_last_case_without_abort: {
     options = {
         switches: true,