fix side-effects detection on switch statements (#1678)

extension of #1675

2 files changed, 36 insertions, 0 deletions

diff --git a/lib/compress.js b/lib/compress.js
index c57287bf..8d8387f2 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1610,6 +1610,10 @@ merge(Compressor.prototype, {
         def(AST_Block, function(compressor){
             return any(this.body, compressor);
         });
+        def(AST_Case, function(compressor){
+            return any(this.body, compressor)
+                || this.expression.has_side_effects(compressor);
+        });
         def(AST_Try, function(compressor){
             return any(this.body, compressor)
                 || this.bcatch && this.bcatch.has_side_effects(compressor)
diff --git a/test/compress/issue-1673.js b/test/compress/issue-1673.js
index 59686abf..4628e37c 100644
--- a/test/compress/issue-1673.js
+++ b/test/compress/issue-1673.js
@@ -125,3 +125,35 @@ side_effects_label: {
     }
     expect_stdout: "PASS"
 }
+
+side_effects_switch: {
+    options = {
+        reduce_vars: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            function g() {
+                switch (0) {
+                  default:
+                  case console.log("PASS"):
+                }
+            }
+            g();
+        }
+        f();
+    }
+    expect: {
+        function f() {
+            (function() {
+                switch (0) {
+                  default:
+                  case console.log("PASS"):
+                }
+            })();
+        }
+        f();
+    }
+    expect_stdout: "PASS"
+}