fix(es/compat): Fix the position for temp var injection (#7171)

Author: magic-akari

crates/swc_ecma_transforms_compat/src/es2021/logical_assignments.rs

@@ -1,3 +1,5 @@
+use std::mem;
+
 use swc_common::{util::take::Take, DUMMY_SP};
 use swc_ecma_ast::*;
 use swc_ecma_transforms_base::perf::Parallel;
@@ -173,34 +175,44 @@ impl VisitMut for Operators {
         }
     }
 
+    /// [swc_ecma_ast::ModuleItem] is the top level Item in the current
+    /// implementation of JavaScript until the proposal for
+    /// [module-declarations] and [module-expressions] are officially added.
+    ///
+    /// [module declarations]: https://github.com/tc39/proposal-module-declarations.
+    /// [module-expressions]: https://github.com/tc39/proposal-module-expressions
     fn visit_mut_module_items(&mut self, n: &mut Vec<ModuleItem>) {
+        let vars = self.vars.take();
         n.visit_mut_children_with(self);
 
-        if !self.vars.is_empty() {
+        let vars = mem::replace(&mut self.vars, vars);
+        if !vars.is_empty() {
             prepend_stmt(
                 n,
                 VarDecl {
                     span: DUMMY_SP,
                     kind: VarDeclKind::Var,
                     declare: false,
-                    decls: self.vars.take(),
+                    decls: vars,
                 }
                 .into(),
             )
         }
     }
 
     fn visit_mut_stmts(&mut self, n: &mut Vec<Stmt>) {
+        let vars = self.vars.take();
         n.visit_mut_children_with(self);
 
-        if !self.vars.is_empty() {
+        let vars = mem::replace(&mut self.vars, vars);
+        if !vars.is_empty() {
             prepend_stmt(
                 n,
                 VarDecl {
                     span: DUMMY_SP,
                     kind: VarDeclKind::Var,
                     declare: false,
-                    decls: self.vars.take(),
+                    decls: vars,
                 }
                 .into(),
             )

crates/swc_ecma_transforms_compat/tests/es2021_logcal_assignments.rs

@@ -79,6 +79,23 @@ test!(
     "
 );
 
+test!(
+    syntax(),
+    |_| tr(),
+    issue_7169,
+    "function myFunc(options) {
+      options.context ||= {}
+      const closure = function() {}
+    }",
+    "
+    function myFunc(options) {
+      var _options;
+      (_options = options).context || (_options.context = {});
+      const closure = function() {};
+    }
+    "
+);
+
 test_exec!(
     syntax(),
     |_| tr(),