fix(es/minifier): should not drop statements which has side-effects

crates/swc_ecma_minifier/src/compress/optimize/mod.rs

@@ -1918,15 +1918,22 @@ where
             #[cfg(feature = "debug")]
             let start = dump(&n.expr, true);
 
-            let expr = self.ignore_return_value(&mut n.expr);
-            n.expr = expr.map(Box::new).unwrap_or_else(|| {
-                report_change!("visit_mut_expr_stmt: Dropped an expression statement");
-
-                #[cfg(feature = "debug")]
-                dump_change_detail!("Removed {}", start);
-
-                undefined(DUMMY_SP)
-            });
+            let is_object_lit_with_spread = n
+                .expr
+                .as_object()
+                .map(|object_lit| object_lit.props.iter().any(|prop| prop.is_spread()))
+                .unwrap_or(false);
+
+            if !is_object_lit_with_spread {
+                let expr = self.ignore_return_value(&mut n.expr);
+                n.expr = expr.map(Box::new).unwrap_or_else(|| {
+                    report_change!("visit_mut_expr_stmt: Dropped an expression statement");
+                    #[cfg(feature = "debug")]
+                    dump_change_detail!("Removed {}", start);
+
+                    undefined(DUMMY_SP)
+                });
+            }
         } else {
             match &mut *n.expr {
                 Expr::Seq(e) => {

crates/swc_ecma_minifier/tests/fixture/issues/6422/2/config.json

@@ -0,0 +1,4 @@
+{
+    "toplevel": true,
+    "unused": true
+}

crates/swc_ecma_minifier/tests/fixture/issues/6422/2/input.js

@@ -0,0 +1,10 @@
+import assert from 'assert'
+let result = 'FAIL';
+const unused = {
+    ...{
+        get prop() {
+            result = 'PASS';
+        }
+    }
+};
+assert.strictEqual(result, 'PASS');

crates/swc_ecma_minifier/tests/fixture/issues/6422/2/output.js

@@ -0,0 +1,10 @@
+import assert from 'assert';
+let result = 'FAIL';
+({
+    ...{
+        get prop () {
+            result = 'PASS';
+        }
+    }
+});
+assert.strictEqual(result, 'PASS');

crates/swc_ecma_minifier/tests/fixture/issues/6422/3/config.json

@@ -0,0 +1,4 @@
+{
+    "toplevel": true,
+    "unused": true
+}

crates/swc_ecma_minifier/tests/fixture/issues/6422/3/input.js

@@ -0,0 +1,18 @@
+import assert from 'assert'
+let result = 0;
+const unused = {
+    ...{
+        get prop() {
+            result = 1;
+        }
+    },
+    [assert.strictEqual(result, 1)]: null,
+    [result = 2]: null,
+    [assert.strictEqual(result, 2)]: null,
+    ...{
+        get prop() {
+            result = 3;
+        }
+    }
+};
+assert.strictEqual(result, 3);

crates/swc_ecma_minifier/tests/fixture/issues/6422/3/output.js

@@ -0,0 +1,18 @@
+import assert from 'assert';
+let result = 0;
+({
+    ...{
+        get prop () {
+            result = 1;
+        }
+    },
+    [assert.strictEqual(result, 1)]: null,
+    [result = 2]: null,
+    [assert.strictEqual(result, 2)]: null,
+    ...{
+        get prop () {
+            result = 3;
+        }
+    }
+});
+assert.strictEqual(result, 3);