Add case for respecting side-effect of getter and setter

swc-project · Nov 18, 2022 · eb5745d · eb5745d
1 parent e8f930d
commit eb5745d
Show file tree

Hide file tree

Showing 6 changed files with 68 additions and 10 deletions.
diff --git a/crates/swc_atoms/words.txt b/crates/swc_atoms/words.txt
@@ -1369,3 +1369,4 @@ ychannelselector
 yield
 zoomAndPan
 zoomandpan
+__proto__
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/mod.rs b/crates/swc_ecma_minifier/src/compress/optimize/mod.rs
@@ -1918,6 +1918,7 @@ where
             #[cfg(feature = "debug")]
             let start = dump(&n.expr, true);
 
+            // Fix https://github.com/swc-project/swc/issues/6422
             let is_object_lit_with_spread = n
                 .expr
                 .as_object()
@@ -2572,6 +2573,7 @@ where
                 if can_be_removed {
                     self.changed = true;
                     report_change!("unused: Dropping an expression without side effect");
+                    tracing::debug!("unused: Dropping \n{}\n", dump(&*expr, false));
                     dump_change_detail!("unused: Dropping \n{}\n", dump(&*expr, false));
                     *s = Stmt::Empty(EmptyStmt { span: DUMMY_SP });
                     return;

diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/6422/1/config.json b/crates/swc_ecma_minifier/tests/fixture/issues/6422/1/config.json
@@ -0,0 +1,5 @@
+{
+    "collapse_vars": true,
+    "unused": true,
+    "toplevel": true
+}
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/6422/1/input.js b/crates/swc_ecma_minifier/tests/fixture/issues/6422/1/input.js
@@ -0,0 +1,21 @@
+let getter_effect = 'FAIL';
+let setter_effect = 'FAIL';
+let proto = {
+    get foo() {
+        getter_effect = 'PASS';
+    },
+    set bar(value) {
+        setter_effect = 'PASS';
+    }
+};
+let obj1 = {
+    __proto__: proto
+};
+let obj2 = {
+    __proto__: proto
+};
+let unused = obj1.foo;
+obj2.bar = 0;
+
+assert.strictEqual(getter_effect, 'PASS');
+assert.strictEqual(setter_effect, 'PASS');
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/6422/1/output.js b/crates/swc_ecma_minifier/tests/fixture/issues/6422/1/output.js
@@ -0,0 +1,18 @@
+let getter_effect = 'FAIL';
+let setter_effect = 'FAIL';
+let proto = {
+    get foo () {
+        getter_effect = 'PASS';
+    },
+    set bar (value){
+        setter_effect = 'PASS';
+    }
+};
+({
+    __proto__: proto
+}).foo;
+({
+    __proto__: proto
+}).bar = 0;
+assert.strictEqual(getter_effect, 'PASS');
+assert.strictEqual(setter_effect, 'PASS');
diff --git a/crates/swc_ecma_utils/src/lib.rs b/crates/swc_ecma_utils/src/lib.rs
@@ -1375,18 +1375,29 @@ pub trait ExprExt {
                         }
                     }
                     Expr::Object(obj) => {
-                        let is_static_accessor = |prop: &PropOrSpread| {
-                            if let PropOrSpread::Prop(prop) = prop {
-                                if let Prop::Getter(_) | Prop::Setter(_) = &**prop {
-                                    true
-                                } else {
-                                    false
-                                }
-                            } else {
-                                false
+                        let is_prop_could_has_side_effect = |prop: &PropOrSpread| {
+                            match prop {
+                                // ({ ...{ __proto__: { get foo() { a = 1; } }  } }).foo
+                                PropOrSpread::Spread(_) => true,
+                                PropOrSpread::Prop(prop) => match prop.as_ref() {
+                                    Prop::Shorthand(ident) => ident.sym == js_word!("__proto__"),
+                                    Prop::KeyValue(KeyValueProp { key, value, .. }) => match key {
+                                        PropName::Ident(ident) => {
+                                            ident.sym == js_word!("__proto__")
+                                        }
+                                        PropName::Str(str) => str.value == js_word!("__proto__"),
+                                        PropName::Computed(_) => true,
+                                        _ => false,
+                                    },
+                                    Prop::Getter(..) | Prop::Setter(..) => true,
+                                    Prop::Method(prop) => true,
+                                    Prop::Assign(_) => {
+                                        unreachable!("This is **invalid** for object literal")
+                                    }
+                                },
                             }
                         };
-                        if obj.props.iter().any(is_static_accessor) {
+                        if obj.props.iter().any(is_prop_could_has_side_effect) {
                             return true;
                         }
                     }