fix(minifier): do not constant fold 0 instanceof F (#8199)

crates/oxc_ecmascript/src/constant_evaluation/mod.rs

@@ -352,22 +352,17 @@ pub trait ConstantEvaluation<'a> {
                 if left.may_have_side_effects() {
                     return None;
                 }
-
-                let left_ty = ValueType::from(left);
-                if left_ty == ValueType::Undetermined {
-                    return None;
-                }
-                if left_ty == ValueType::Object {
-                    if let Some(right_ident) = right.get_identifier_reference() {
-                        if right_ident.name == "Object" && self.is_global_reference(right_ident) {
-                            return Some(ConstantValue::Boolean(true));
-                        }
+                if let Some(right_ident) = right.get_identifier_reference() {
+                    let name = right_ident.name.as_str();
+                    if matches!(name, "Object" | "Number" | "Boolean" | "String")
+                        && self.is_global_reference(right_ident)
+                    {
+                        return Some(ConstantValue::Boolean(
+                            name == "Object" && ValueType::from(left).is_object(),
+                        ));
                     }
-                    None
-                } else {
-                    // Non-object types are never instances.
-                    Some(ConstantValue::Boolean(false))
                 }
+                None
             }
             _ => None,
         }

crates/oxc_ecmascript/src/constant_evaluation/value_type.rs

@@ -40,6 +40,10 @@ impl ValueType {
     pub fn is_boolean(self) -> bool {
         self == Self::Boolean
     }
+
+    pub fn is_object(self) -> bool {
+        self == Self::Object
+    }
 }
 
 /// `get_known_value_type`

crates/oxc_minifier/src/ast_passes/peephole_fold_constants.rs

@@ -1609,6 +1609,7 @@ mod test {
 
         // An unknown value should never be folded.
         test_same("x instanceof Foo");
+        test_same("0 instanceof Foo");
     }
 
     #[test]