fix(es/minifier): Abort seq inliner on ** (#8947)

**Related issue:** - Closes #8942

Author: kdy1

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

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);
  }
  }

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(

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;
+})();