From d53c4a9eba3bc3c4dbad9ea3c4f702c71ec92c75 Mon Sep 17 00:00:00 2001
From: Boshen <boshenc@gmail.com>
Date: Fri, 10 Jan 2025 13:16:39 +0800
Subject: [PATCH] fix(minifier): `a in b` has error throwing side effect

---
 .../src/side_effects/check_for_state_change.rs             | 7 +++----
 .../src/ast_passes/peephole_remove_dead_code.rs            | 1 +
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/crates/oxc_ecmascript/src/side_effects/check_for_state_change.rs b/crates/oxc_ecmascript/src/side_effects/check_for_state_change.rs
index 331d1f46b9731d..94dd82117aac4b 100644
--- a/crates/oxc_ecmascript/src/side_effects/check_for_state_change.rs
+++ b/crates/oxc_ecmascript/src/side_effects/check_for_state_change.rs
@@ -1,5 +1,5 @@
 use oxc_ast::ast::*;
-use oxc_syntax::operator::UnaryOperator;
+use oxc_syntax::operator::{BinaryOperator, UnaryOperator};
 
 /// A "simple" operator is one whose children are expressions, has no direct side-effects.
 fn is_simple_unary_operator(operator: UnaryOperator) -> bool {
@@ -63,7 +63,6 @@ impl<'a> CheckForStateChange<'a, '_> for Expression<'a> {
                 if check_for_new_objects {
                     return true;
                 }
-
                 object_expr
                     .properties
                     .iter()
@@ -95,8 +94,8 @@ impl<'a> CheckForStateChange<'a, '_> for UnaryExpression<'a> {
 
 impl<'a> CheckForStateChange<'a, '_> for BinaryExpression<'a> {
     fn check_for_state_change(&self, check_for_new_objects: bool) -> bool {
-        // `instanceof` can throw `TypeError`
-        if self.operator.is_instance_of() {
+        // `instanceof` and `in` can throw `TypeError`
+        if matches!(self.operator, BinaryOperator::In | BinaryOperator::Instanceof) {
             return true;
         }
         let left = self.left.check_for_state_change(check_for_new_objects);
diff --git a/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs b/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs
index 76e5db8c98a436..e26a3668375807 100644
--- a/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs
+++ b/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs
@@ -718,6 +718,7 @@ mod test {
         fold_same("(0, o.f)();");
         fold("var obj = Object((null, 2, 3), 1, 2);", "var obj = Object(3, 1, 2);");
         fold_same("(0 instanceof 0, foo)");
+        fold_same("(0 in 0, foo)");
     }
 
     #[test]