From 77da7cf24bad5064206ab3e6dc248012d08576cf 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, 29 Jul 2024 12:23:20 +0900
Subject: [PATCH] fix(es/minifier): Fix detection of `this` (#9339)

**Related issue:**

 - Closes https://github.com/swc-project/swc/issues/9148
---
 .changeset/wicked-pandas-lick.md              |  5 +++
 .../src/compress/optimize/unused.rs           | 32 +++++++++++++++++++
 .../tests/fixture/issues/8643/output.js       |  6 ++++
 .../tests/fixture/issues/9148/input.js        | 16 ++++++++++
 .../tests/fixture/issues/9148/output.js       | 14 ++++++++
 .../hoist_props/contains_this_1/output.js     |  8 ++++-
 6 files changed, 80 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/wicked-pandas-lick.md
 create mode 100644 crates/swc_ecma_minifier/tests/fixture/issues/9148/input.js
 create mode 100644 crates/swc_ecma_minifier/tests/fixture/issues/9148/output.js

diff --git a/.changeset/wicked-pandas-lick.md b/.changeset/wicked-pandas-lick.md
new file mode 100644
index 000000000000..065723c8b758
--- /dev/null
+++ b/.changeset/wicked-pandas-lick.md
@@ -0,0 +1,5 @@
+---
+swc_ecma_minifier: patch
+---
+
+fix(es/minifier): Fix detection of `this`
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/unused.rs b/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
index 2460f92ebc06..f8a74dd55712 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
@@ -846,6 +846,38 @@ impl Optimizer<'_> {
                 PropOrSpread::Prop(prop) => prop,
             };
 
+            match &**prop {
+                Prop::Method(prop) => {
+                    if contains_this_expr(&prop.function.body) {
+                        return None;
+                    }
+                }
+                Prop::Getter(prop) => {
+                    if contains_this_expr(&prop.body) {
+                        return None;
+                    }
+                }
+                Prop::Setter(prop) => {
+                    if contains_this_expr(&prop.body) {
+                        return None;
+                    }
+                }
+                Prop::KeyValue(prop) => match &*prop.value {
+                    Expr::Fn(f) => {
+                        if contains_this_expr(&f.function.body) {
+                            return None;
+                        }
+                    }
+                    Expr::Arrow(f) => {
+                        if contains_this_expr(&f.body) {
+                            return None;
+                        }
+                    }
+                    _ => {}
+                },
+                _ => {}
+            }
+
             if contains_this_expr(prop) {
                 return None;
             }
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/8643/output.js b/crates/swc_ecma_minifier/tests/fixture/issues/8643/output.js
index 77bd2e581726..2383456174bf 100644
--- a/crates/swc_ecma_minifier/tests/fixture/issues/8643/output.js
+++ b/crates/swc_ecma_minifier/tests/fixture/issues/8643/output.js
@@ -8,6 +8,12 @@ const Cache = {
     get: function(key) {
         if (!1 !== this.enabled) // console.log( 'THREE.Cache', 'Checking key:', key );
         return this.files[key];
+    },
+    remove: function(key) {
+        delete this.files[key];
+    },
+    clear: function() {
+        this.files = {};
     }
 };
 class Loader {
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/9148/input.js b/crates/swc_ecma_minifier/tests/fixture/issues/9148/input.js
new file mode 100644
index 000000000000..b60597f8f335
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/fixture/issues/9148/input.js
@@ -0,0 +1,16 @@
+function foo() {
+    const obj = {
+        clear: function () {
+            console.log('clear')
+        },
+        start: function () {
+            const _this = this;
+            setTimeout(function () {
+                _this.clear();
+            });
+        }
+    };
+    return () => obj.start()
+};
+
+export default foo()
\ No newline at end of file
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/9148/output.js b/crates/swc_ecma_minifier/tests/fixture/issues/9148/output.js
new file mode 100644
index 000000000000..9c6db76fcaaa
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/fixture/issues/9148/output.js
@@ -0,0 +1,14 @@
+export default (function() {
+    const obj = {
+        clear: function() {
+            console.log('clear');
+        },
+        start: function() {
+            const _this = this;
+            setTimeout(function() {
+                _this.clear();
+            });
+        }
+    };
+    return ()=>obj.start();
+})();
diff --git a/crates/swc_ecma_minifier/tests/terser/compress/hoist_props/contains_this_1/output.js b/crates/swc_ecma_minifier/tests/terser/compress/hoist_props/contains_this_1/output.js
index 76f60763a8db..ca168451f516 100644
--- a/crates/swc_ecma_minifier/tests/terser/compress/hoist_props/contains_this_1/output.js
+++ b/crates/swc_ecma_minifier/tests/terser/compress/hoist_props/contains_this_1/output.js
@@ -1 +1,7 @@
-console.log(1, 1);
+var o = {
+    u: function() {
+        return this === this;
+    },
+    p: 1
+};
+console.log(o.p, o.p);