From b394f9f1d3efd24fd55b4ac5efdbaee91b9d8021 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: Tue, 29 Nov 2022 13:12:11 +0900
Subject: [PATCH] fix(es/minifier): Don't drop used variables from sequential
 inliner (#6520)

**Related issue:**

 - Closes https://github.com/swc-project/swc/issues/6510.
---
 .../nonPrimitiveAssignError.2.minified.js     |  2 +-
 .../src/compress/optimize/sequences.rs        |  3 ++-
 .../tests/fixture/next/joda/input.js          | 26 +++++++++++++++++++
 .../tests/fixture/next/joda/output.js         | 15 +++++++++++
 .../tests/pass-1/joda/1/input.js              | 26 +++++++++++++++++++
 .../tests/pass-1/joda/1/output.js             | 19 ++++++++++++++
 .../tests/pass-1/joda/2/input.js              | 19 ++++++++++++++
 .../tests/pass-1/joda/2/output.js             | 17 ++++++++++++
 8 files changed, 125 insertions(+), 2 deletions(-)
 create mode 100644 crates/swc_ecma_minifier/tests/fixture/next/joda/input.js
 create mode 100644 crates/swc_ecma_minifier/tests/fixture/next/joda/output.js
 create mode 100644 crates/swc_ecma_minifier/tests/pass-1/joda/1/input.js
 create mode 100644 crates/swc_ecma_minifier/tests/pass-1/joda/1/output.js
 create mode 100644 crates/swc_ecma_minifier/tests/pass-1/joda/2/input.js
 create mode 100644 crates/swc_ecma_minifier/tests/pass-1/joda/2/output.js

diff --git a/crates/swc/tests/tsc-references/nonPrimitiveAssignError.2.minified.js b/crates/swc/tests/tsc-references/nonPrimitiveAssignError.2.minified.js
index 7e8ffe4f413c..d1d30ad8d3d6 100644
--- a/crates/swc/tests/tsc-references/nonPrimitiveAssignError.2.minified.js
+++ b/crates/swc/tests/tsc-references/nonPrimitiveAssignError.2.minified.js
@@ -4,4 +4,4 @@ var a, x = {}, y = {
 };
 x = a, y = a, a = x, a = y;
 var s = "fooo";
-a = 123, a = !0, n = a = s, b = a, s = a, a = 123, a = !0, a = "string";
+a = 123, a = !0, s = a = s, a = 123, a = !0, a = "string";
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs b/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs
index fb4d45086cdb..b45d9a9b4a6d 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs
@@ -2222,7 +2222,8 @@ where
                             if let Some(usage) = self.data.vars.get(&left_id.to_id()) {
                                 // We are eliminating one usage, so we use 1 instead of
                                 // 0
-                                if !$force_drop && usage.usage_count == 1 {
+                                if !$force_drop && usage.usage_count == 1 && usage.assign_count == 0
+                                {
                                     report_change!("sequences: Dropping inlined variable");
                                     a.name.take();
                                 }
diff --git a/crates/swc_ecma_minifier/tests/fixture/next/joda/input.js b/crates/swc_ecma_minifier/tests/fixture/next/joda/input.js
new file mode 100644
index 000000000000..f94d74fc67bb
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/fixture/next/joda/input.js
@@ -0,0 +1,26 @@
+"use strict";
+(self["webpackChunk_N_E"] = self["webpackChunk_N_E"] || []).push([[715], {
+
+/***/ 3266:
+/***/ (function (__unused_webpack_module, __webpack_exports__, __webpack_require__) {
+
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "h": function () { return /* binding */ LocalDate; }
+  /* harmony export */
+});
+
+      var isInit = false;
+
+      function init() {
+        if (isInit) {
+          return;
+        }
+
+        isInit = true;
+      }
+
+      init();
+
+    })
+
+}]);
\ No newline at end of file
diff --git a/crates/swc_ecma_minifier/tests/fixture/next/joda/output.js b/crates/swc_ecma_minifier/tests/fixture/next/joda/output.js
new file mode 100644
index 000000000000..b5a63dd451f1
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/fixture/next/joda/output.js
@@ -0,0 +1,15 @@
+"use strict";
+(self.webpackChunk_N_E = self.webpackChunk_N_E || []).push([
+    [
+        715
+    ],
+    {
+        3266: function(__unused_webpack_module, __webpack_exports__, __webpack_require__) {
+            __webpack_require__.d(__webpack_exports__, {
+                h: function() {
+                    return LocalDate;
+                }
+            });
+        }
+    }
+]);
diff --git a/crates/swc_ecma_minifier/tests/pass-1/joda/1/input.js b/crates/swc_ecma_minifier/tests/pass-1/joda/1/input.js
new file mode 100644
index 000000000000..f94d74fc67bb
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/pass-1/joda/1/input.js
@@ -0,0 +1,26 @@
+"use strict";
+(self["webpackChunk_N_E"] = self["webpackChunk_N_E"] || []).push([[715], {
+
+/***/ 3266:
+/***/ (function (__unused_webpack_module, __webpack_exports__, __webpack_require__) {
+
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "h": function () { return /* binding */ LocalDate; }
+  /* harmony export */
+});
+
+      var isInit = false;
+
+      function init() {
+        if (isInit) {
+          return;
+        }
+
+        isInit = true;
+      }
+
+      init();
+
+    })
+
+}]);
\ No newline at end of file
diff --git a/crates/swc_ecma_minifier/tests/pass-1/joda/1/output.js b/crates/swc_ecma_minifier/tests/pass-1/joda/1/output.js
new file mode 100644
index 000000000000..c13efe64f565
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/pass-1/joda/1/output.js
@@ -0,0 +1,19 @@
+"use strict";
+(self.webpackChunk_N_E = self.webpackChunk_N_E || []).push([
+    [
+        715
+    ],
+    {
+        3266: function(__unused_webpack_module, __webpack_exports__, __webpack_require__) {
+            __webpack_require__.d(__webpack_exports__, {
+                h: function() {
+                    return LocalDate;
+                }
+            });
+            var isInit = !1;
+            !function() {
+                if (!isInit) isInit = !0;
+            }();
+        }
+    }
+]);
diff --git a/crates/swc_ecma_minifier/tests/pass-1/joda/2/input.js b/crates/swc_ecma_minifier/tests/pass-1/joda/2/input.js
new file mode 100644
index 000000000000..c0d515401cb1
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/pass-1/joda/2/input.js
@@ -0,0 +1,19 @@
+"use strict";
+(self.webpackChunk_N_E = self.webpackChunk_N_E || []).push([
+  [
+    715
+  ],
+  {
+    3266: function (__unused_webpack_module, __webpack_exports__, __webpack_require__) {
+      __webpack_require__.d(__webpack_exports__, {
+        h: function () {
+          return LocalDate;
+        }
+      });
+      var isInit = !1;
+      !function () {
+        if (!isInit) isInit = !0;
+      }();
+    }
+  }
+]);
diff --git a/crates/swc_ecma_minifier/tests/pass-1/joda/2/output.js b/crates/swc_ecma_minifier/tests/pass-1/joda/2/output.js
new file mode 100644
index 000000000000..778d2ac031cd
--- /dev/null
+++ b/crates/swc_ecma_minifier/tests/pass-1/joda/2/output.js
@@ -0,0 +1,17 @@
+"use strict";
+(self.webpackChunk_N_E = self.webpackChunk_N_E || []).push([
+    [
+        715
+    ],
+    {
+        3266: function(__unused_webpack_module, __webpack_exports__, __webpack_require__) {
+            __webpack_require__.d(__webpack_exports__, {
+                h: function() {
+                    return LocalDate;
+                }
+            });
+            var isInit = !1;
+            isInit = !0;
+        }
+    }
+]);