From 811308c3526003608e61c559f43408f6065ff9ee 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: Fri, 5 Apr 2024 09:02:51 +0900
Subject: [PATCH] fix(es/minifier): Respect `top_retain` for top-level
 functions (#8814)

---
 crates/swc_ecma_minifier/src/compress/optimize/unused.rs  | 8 ++++++++
 crates/swc_ecma_minifier/tests/TODO.txt                   | 1 -
 .../drop_unused/drop_toplevel_all_retain/output.js        | 4 +---
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/crates/swc_ecma_minifier/src/compress/optimize/unused.rs b/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
index 79ebff51d8f3..eaa2b047f2da 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
@@ -511,6 +511,14 @@ impl Optimizer<'_> {
                     return;
                 }
 
+                if !self.may_remove_ident(ident) {
+                    log_abort!(
+                        "unused: Preserving function `{}` because it's top-level",
+                        ident.sym
+                    );
+                    return;
+                }
+
                 // If it is not used, drop it.
                 if self
                     .data
diff --git a/crates/swc_ecma_minifier/tests/TODO.txt b/crates/swc_ecma_minifier/tests/TODO.txt
index cec001dfbdf4..4896a84541ec 100644
--- a/crates/swc_ecma_minifier/tests/TODO.txt
+++ b/crates/swc_ecma_minifier/tests/TODO.txt
@@ -88,7 +88,6 @@ drop_unused/delete_assign_1/input.js
 drop_unused/delete_assign_2/input.js
 drop_unused/double_assign_1/input.js
 drop_unused/double_assign_2/input.js
-drop_unused/drop_toplevel_all_retain/input.js
 drop_unused/drop_toplevel_funcs/input.js
 drop_unused/drop_toplevel_funcs_retain/input.js
 drop_unused/drop_toplevel_keep_assign/input.js
diff --git a/crates/swc_ecma_minifier/tests/terser/compress/drop_unused/drop_toplevel_all_retain/output.js b/crates/swc_ecma_minifier/tests/terser/compress/drop_unused/drop_toplevel_all_retain/output.js
index 888671e8b76a..b2374bce8bb2 100644
--- a/crates/swc_ecma_minifier/tests/terser/compress/drop_unused/drop_toplevel_all_retain/output.js
+++ b/crates/swc_ecma_minifier/tests/terser/compress/drop_unused/drop_toplevel_all_retain/output.js
@@ -1,8 +1,6 @@
 var a;
 function f(d) {
-    return function () {
-        2;
-    };
+    return function() {};
 }
 a = 2;
 console.log(3);