From 3046d71daa77327e7b211cfdb641e3e6148bea5f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Donny/=EA=B0=95=EB=8F=99=EC=9C=A4?= <kdy1997.dev@gmail.com>
Date: Mon, 13 May 2024 10:11:46 +0900
Subject: [PATCH] fix(es/minifier): Abort seq inliner on `**` (#8947)

**Related issue:**

 - Closes #8942
---
 .../src/compress/optimize/dead_code.rs            |  4 ++++
 .../src/compress/optimize/sequences.rs            |  3 ++-
 crates/swc_ecma_minifier/tests/exec.rs            | 15 +++++++++++++++
 .../tests/fixture/issues/8924/output.js           |  5 ++++-
 4 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/crates/swc_ecma_minifier/src/compress/optimize/dead_code.rs b/crates/swc_ecma_minifier/src/compress/optimize/dead_code.rs
index 614a2fc5a477..bbf2bc224b76 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/dead_code.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/dead_code.rs
@@ -68,6 +68,10 @@ impl Optimizer<'_> {
         if let Expr::Assign(assign) = e {
             // x += 1 => x + 1
             if let Some(op) = assign.op.to_update() {
+                if op == op!("**") {
+                    return false;
+                }
+
                 if let Some(lhs) = assign.left.as_ident() {
                     //
                     if self
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs b/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs
index 415b21eb98e1..9ea419d07fe1 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs
@@ -1562,6 +1562,7 @@ impl Optimizer<'_> {
             | Expr::Tpl(..)
             | Expr::TaggedTpl(..) => return Ok(false),
 
+            // See https://github.com/swc-project/swc/issues/8924 and https://github.com/swc-project/swc/issues/8942
             Expr::Assign(AssignExpr {
                 op: op!("**="),
                 right,
@@ -1572,7 +1573,7 @@ impl Optimizer<'_> {
                 right,
                 ..
             }) => {
-                if is_pure_undefined(&self.expr_ctx, right) {
+                if !right.is_lit() {
                     return Ok(false);
                 }
             }
diff --git a/crates/swc_ecma_minifier/tests/exec.rs b/crates/swc_ecma_minifier/tests/exec.rs
index d3224adc019c..ff42d211314f 100644
--- a/crates/swc_ecma_minifier/tests/exec.rs
+++ b/crates/swc_ecma_minifier/tests/exec.rs
@@ -11224,6 +11224,21 @@ console.log(eval(foo));",
     );
 }
 
+#[test]
+fn issue_8942() {
+    run_default_exec_test(
+        "
+        'use strict';
+        const k = (() => {
+            let x = 1;
+            x **= undefined / x;
+            return x;
+        })();
+        console.log(k);
+        ",
+    );
+}
+
 #[test]
 fn issue_8937() {
     run_default_exec_test(
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/8924/output.js b/crates/swc_ecma_minifier/tests/fixture/issues/8924/output.js
index f010cc298f42..c254dba096a6 100644
--- a/crates/swc_ecma_minifier/tests/fixture/issues/8924/output.js
+++ b/crates/swc_ecma_minifier/tests/fixture/issues/8924/output.js
@@ -1,2 +1,5 @@
 "use strict";
-const k = NaN;
+const k = (()=>{
+    let x = 1;
+    return x **= void 0;
+})();