fix corner case in switches (#5011)

fixes #5010

lib/compress.js

@@ -8506,7 +8506,7 @@ merge(Compressor.prototype, {
             }));
             return make_node(AST_BlockStatement, self, { body: decl }).optimize(compressor);
         }
-        if (exact_match ? !branch.expression.has_side_effects(compressor) : branch === default_branch) {
+        if (branch === default_branch || branch === exact_match && !branch.expression.has_side_effects(compressor)) {
             while (branch = body[body.length - 2]) {
                 if (branch instanceof AST_Default) break;
                 if (!has_declarations_only(branch)) break;

test/compress/switches.js

@@ -1556,3 +1556,29 @@ issue_5008_4: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5010: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        var a;
+        switch (42) {
+          case console.log("PASS"):
+          case a:
+            console.log("FAIL");
+          case 42:
+        }
+    }
+    expect: {
+        var a;
+        switch (42) {
+          case console.log("PASS"):
+          case a:
+            console.log("FAIL");
+        }
+    }
+    expect_stdout: "PASS"
+}