From 985977b750d458d0ccbdff8b2b779224a917a66b 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, 2 Dec 2024 13:43:47 +0900
Subject: [PATCH] fix(es/minifier): Do not inline into the exact LHS (#9777)
**Related issue:**
- Closes https://github.com/swc-project/swc/issues/9739
---
.changeset/big-mails-kneel.md | 6 +++
.../src/compress/optimize/inline.rs | 4 ++
.../tests/fixture/issues/9739/config.json | 46 +++++++++++++++++++
.../tests/fixture/issues/9739/input.js | 2 +
.../tests/fixture/issues/9739/output.js | 8 ++++
5 files changed, 66 insertions(+)
create mode 100644 .changeset/big-mails-kneel.md
create mode 100644 crates/swc_ecma_minifier/tests/fixture/issues/9739/config.json
create mode 100644 crates/swc_ecma_minifier/tests/fixture/issues/9739/input.js
create mode 100644 crates/swc_ecma_minifier/tests/fixture/issues/9739/output.js
diff --git a/.changeset/big-mails-kneel.md b/.changeset/big-mails-kneel.md
new file mode 100644
index 000000000000..6aae8f1c4891
--- /dev/null
+++ b/.changeset/big-mails-kneel.md
@@ -0,0 +1,6 @@
+---
+swc_core: patch
+swc_ecma_minifier: patch
+---
+
+fix(es/minifier): Do not inline into the exact LHS
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/inline.rs b/crates/swc_ecma_minifier/src/compress/optimize/inline.rs
index 2456e01cd819..d8705cd9f443 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/inline.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/inline.rs
@@ -789,6 +789,10 @@ impl Optimizer<'_> {
/// Actually inlines variables.
pub(super) fn inline(&mut self, e: &mut Expr) {
+ if self.ctx.is_exact_lhs_of_assign {
+ return;
+ }
+
match e {
Expr::Member(me) => {
if let MemberProp::Computed(prop) = &mut me.prop {
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/9739/config.json b/crates/swc_ecma_minifier/tests/fixture/issues/9739/config.json
new file mode 100644
index 000000000000..e24c2f770eb5
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/fixture/issues/9739/config.json
@@ -0,0 +1,46 @@
+{
+ "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": true,
+ "const_to_let": true,
+ "pristine_globals": true
+}
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/9739/input.js b/crates/swc_ecma_minifier/tests/fixture/issues/9739/input.js
new file mode 100644
index 000000000000..026bf482667d
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/fixture/issues/9739/input.js
@@ -0,0 +1,2 @@
+const arr = ['a', 'b'];
+[arr[0], arr[1]] = [arr[1], arr[0]];
\ No newline at end of file
diff --git a/crates/swc_ecma_minifier/tests/fixture/issues/9739/output.js b/crates/swc_ecma_minifier/tests/fixture/issues/9739/output.js
new file mode 100644
index 000000000000..a3a2fde32767
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/fixture/issues/9739/output.js
@@ -0,0 +1,8 @@
+const arr = [
+ 'a',
+ 'b'
+];
+[arr[0], arr[1]] = [
+ 'b',
+ 'a'
+];