replMode: keep helper imports and lowering temporaries in the wrapper

packages/bun-types/bun.d.ts

@@ -3054,9 +3054,13 @@ declare module "bun" {
     /**
      * Enable REPL mode transforms:
      * - Wraps top-level inputs that appear to be object literals (inputs starting with '{' without trailing ';') in parentheses
-     * - Hoists all declarations as var for REPL persistence across vm.runInContext calls
+     * - Hoists the declarations the input wrote as var for REPL persistence across vm.runInContext calls.
+     *   A helper import or a temporary that the transpiler adds stays inside the IIFE
      * - Wraps last expression in { __proto__: null, value: expr } for result capture
-     * - Wraps code in sync/async IIFE to avoid parentheses around object literals
+     * - Wraps code in sync/async IIFE to avoid parentheses around object literals.
+     *   The IIFE is async, and the result is a Promise, if the input has a top-level await or an import,
+     *   or if the transpiler imports helpers for it (decorators, `accessor`, a lowered `using`, JSX with `autoImportJSX`).
+     *   An import becomes an `import()` call: with `vm.runInContext`, pass `importModuleDynamically`
      *
      * @default false
      */

src/js_parser/parse/parse_entry.rs

@@ -1096,7 +1096,11 @@ impl<'a> Parser<'a> {
         // because we only do tree-shaking on top-level statements and lowering
         // a top-level "using" declaration moves all top-level statements into a
         // nested scope.
-        if !p.options.tree_shaking || p.will_wrap_module_in_try_catch_for_using {
+        if !p.options.tree_shaking
+            || p.will_wrap_module_in_try_catch_for_using
+            // The REPL transform moves all top-level statements into a function.
+            || p.options.repl_mode
+        {
             // When tree shaking is disabled, everything comes in a single part
             p.append_part(&mut parts, stmts)?;
         } else {