From 102241b812b8e815b59575178193bb71b4264bab 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, 11 Mar 2024 16:59:22 +0900
Subject: [PATCH] fix(es/minifier): Handle cyclic references while dropping
 unused properties (#8725)

**Related issue:**

 - Closes #8714
---
 .../fixture/issues-8xxx/8714/input/.swcrc     | 65 +++++++++++++++++++
 .../tests/fixture/issues-8xxx/8714/input/1.js |  5 ++
 .../fixture/issues-8xxx/8714/output/1.js      |  5 ++
 .../src/compress/optimize/unused.rs           |  2 +-
 .../tests/fixture/issues/8714/config.json     |  3 +
 .../tests/fixture/issues/8714/input.js        |  5 ++
 .../tests/fixture/issues/8714/output.js       |  5 ++
 7 files changed, 89 insertions(+), 1 deletion(-)
 create mode 100644 crates/swc/tests/fixture/issues-8xxx/8714/input/.swcrc
 create mode 100644 crates/swc/tests/fixture/issues-8xxx/8714/input/1.js
 create mode 100644 crates/swc/tests/fixture/issues-8xxx/8714/output/1.js
 create mode 100644 crates/swc_ecma_minifier/tests/fixture/issues/8714/config.json
 create mode 100644 crates/swc_ecma_minifier/tests/fixture/issues/8714/input.js
 create mode 100644 crates/swc_ecma_minifier/tests/fixture/issues/8714/output.js

diff --git a/crates/swc/tests/fixture/issues-8xxx/8714/input/.swcrc b/crates/swc/tests/fixture/issues-8xxx/8714/input/.swcrc
new file mode 100644
index 000000000000..b4f4091fcd6d
--- /dev/null
+++ b/crates/swc/tests/fixture/issues-8xxx/8714/input/.swcrc
@@ -0,0 +1,65 @@
+{
+    "jsc": {
+        "parser": {
+            "syntax": "ecmascript",
+            "jsx": false
+        },
+        "target": "es2022",
+        "loose": false,
+        "minify": {
+            "compress": {
+                "arguments": false,
+                "arrows": true,
+                "booleans": true,
+                "booleans_as_integers": false,
+                "collapse_vars": true,
+                "comparisons": true,
+                "computed_props": true,
+                "conditionals": true,
+                "dead_code": true,
+                "directives": true,
+                "drop_console": false,
+                "drop_debugger": true,
+                "evaluate": true,
+                "expression": false,
+                "hoist_funs": false,
+                "hoist_props": true,
+                "hoist_vars": false,
+                "if_return": true,
+                "join_vars": true,
+                "keep_classnames": false,
+                "keep_fargs": true,
+                "keep_fnames": false,
+                "keep_infinity": false,
+                "loops": true,
+                "negate_iife": true,
+                "properties": true,
+                "reduce_funcs": false,
+                "reduce_vars": false,
+                "side_effects": true,
+                "switches": true,
+                "typeofs": true,
+                "unsafe": false,
+                "unsafe_arrows": false,
+                "unsafe_comps": false,
+                "unsafe_Function": false,
+                "unsafe_math": false,
+                "unsafe_symbols": false,
+                "unsafe_methods": false,
+                "unsafe_proto": false,
+                "unsafe_regexp": false,
+                "unsafe_undefined": false,
+                "unused": false,
+                "const_to_let": true,
+                "pristine_globals": true,
+                "passes": 3
+            },
+            "mangle": false
+        }
+    },
+    "module": {
+        "type": "es6"
+    },
+    "minify": false,
+    "isModule": true
+}
\ No newline at end of file
diff --git a/crates/swc/tests/fixture/issues-8xxx/8714/input/1.js b/crates/swc/tests/fixture/issues-8xxx/8714/input/1.js
new file mode 100644
index 000000000000..88dbc6ebb60b
--- /dev/null
+++ b/crates/swc/tests/fixture/issues-8xxx/8714/input/1.js
@@ -0,0 +1,5 @@
+const foo = {
+    x: 1,
+    y: () => foo
+};
+console.log(foo.y().x); // should log: 1
\ No newline at end of file
diff --git a/crates/swc/tests/fixture/issues-8xxx/8714/output/1.js b/crates/swc/tests/fixture/issues-8xxx/8714/output/1.js
new file mode 100644
index 000000000000..613ae0f8677f
--- /dev/null
+++ b/crates/swc/tests/fixture/issues-8xxx/8714/output/1.js
@@ -0,0 +1,5 @@
+const foo = {
+    x: 1,
+    y: ()=>foo
+};
+console.log(foo.y().x);
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/unused.rs b/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
index 431316f6b258..14b810be9d64 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
@@ -793,7 +793,7 @@ impl Optimizer<'_> {
 
         let usage = self.data.vars.get(&name.to_id())?;
 
-        if usage.indexed_with_dynamic_key || usage.used_as_ref {
+        if usage.indexed_with_dynamic_key || usage.used_as_ref || usage.used_recursively {
             return None;
         }
 
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/8714/config.json b/crates/swc_ecma_minifier/tests/fixture/issues/8714/config.json
new file mode 100644
index 000000000000..ee65e9fdc67e
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/fixture/issues/8714/config.json
@@ -0,0 +1,3 @@
+{
+    "defaults": true
+}
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/8714/input.js b/crates/swc_ecma_minifier/tests/fixture/issues/8714/input.js
new file mode 100644
index 000000000000..c9d684029e7d
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/fixture/issues/8714/input.js
@@ -0,0 +1,5 @@
+const foo = {
+    x: 1,
+    y: () => foo
+};
+console.log(foo.y().x); 
\ No newline at end of file
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/8714/output.js b/crates/swc_ecma_minifier/tests/fixture/issues/8714/output.js
new file mode 100644
index 000000000000..613ae0f8677f
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/fixture/issues/8714/output.js
@@ -0,0 +1,5 @@
+const foo = {
+    x: 1,
+    y: ()=>foo
+};
+console.log(foo.y().x);