From 784796d8693f2a52147b01082afd7be68d837cd3 Mon Sep 17 00:00:00 2001
From: Boshen <1430279+Boshen@users.noreply.github.com>
Date: Sat, 9 Aug 2025 14:46:20 +0000
Subject: [PATCH] feat(minifier): fold `(!0).toString()` to `true` (#12938)

---
 .../src/constant_evaluation/call_expr.rs         | 16 +++++++---------
 .../src/constant_evaluation/value.rs             |  4 ++++
 .../src/peephole/replace_known_methods.rs        |  2 ++
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/crates/oxc_ecmascript/src/constant_evaluation/call_expr.rs b/crates/oxc_ecmascript/src/constant_evaluation/call_expr.rs
index 7de4ca1c1ce90..9441e2b13ad98 100644
--- a/crates/oxc_ecmascript/src/constant_evaluation/call_expr.rs
+++ b/crates/oxc_ecmascript/src/constant_evaluation/call_expr.rs
@@ -324,16 +324,14 @@ fn try_fold_to_string<'a>(
             let result = format_radix(i, radix);
             Some(ConstantValue::String(Cow::Owned(result)))
         }
-        // `null` returns type errors
-        Expression::BooleanLiteral(_)
-        | Expression::NumericLiteral(_)
-        | Expression::BigIntLiteral(_)
-        | Expression::RegExpLiteral(_)
-        | Expression::StringLiteral(_)
-            if args.is_empty() =>
-        {
-            object.to_js_string(ctx).map(ConstantValue::String)
+        Expression::RegExpLiteral(lit) if args.is_empty() => {
+            lit.to_js_string(ctx).map(ConstantValue::String)
         }
+        e if args.is_empty() => e
+            .evaluate_value(ctx)
+            // `null` and `undefined` returns type errors
+            .filter(|v| !v.is_undefined() && !v.is_null())
+            .and_then(|v| v.to_js_string(ctx).map(ConstantValue::String)),
         _ => None,
     }
 }
diff --git a/crates/oxc_ecmascript/src/constant_evaluation/value.rs b/crates/oxc_ecmascript/src/constant_evaluation/value.rs
index 994a3e50ce6d9..40076948a5e48 100644
--- a/crates/oxc_ecmascript/src/constant_evaluation/value.rs
+++ b/crates/oxc_ecmascript/src/constant_evaluation/value.rs
@@ -36,6 +36,10 @@ impl<'a> ConstantValue<'a> {
         matches!(self, Self::Undefined)
     }
 
+    pub fn is_null(&self) -> bool {
+        matches!(self, Self::Null)
+    }
+
     pub fn into_string(self) -> Option<Cow<'a, str>> {
         match self {
             Self::String(s) => Some(s),
diff --git a/crates/oxc_minifier/src/peephole/replace_known_methods.rs b/crates/oxc_minifier/src/peephole/replace_known_methods.rs
index 2d4602b5c8c0a..5ed65b071e137 100644
--- a/crates/oxc_minifier/src/peephole/replace_known_methods.rs
+++ b/crates/oxc_minifier/src/peephole/replace_known_methods.rs
@@ -1486,6 +1486,8 @@ mod test {
         test("x = false['toString']()", "x = 'false';");
         test("x = false.toString()", "x = 'false';");
         test("x = true.toString()", "x = 'true';");
+        test("x = (!0).toString()", "x = 'true';");
+        test("x = (!1).toString()", "x = 'false';");
         test("x = 'xy'.toString()", "x = 'xy';");
         test("x = 0 .toString()", "x = '0';");
         test("x = 123 .toString()", "x = '123';");