repl: import the JSX runtime for JSX input

src/js_parser/parse/parse_entry.rs

@@ -2279,20 +2279,16 @@ impl<'a> Parser<'a> {
             && p.options.features.auto_import_jsx
             && p.options.jsx.runtime == options::JSX::Runtime::Automatic
         {
-            // `generate_import_stmt` takes `&mut self` plus `import_path: &'a [u8]`
-            // and `symbols: &Sym`, so the Pragma-owned `Box<[u8]>` paths are copied into the
-            // bump arena (giving them the required `'a` lifetime) and `jsx_imports` is moved
-            // out via `take` (it is `Default`) to avoid an overlapping `&self.jsx_imports`
-            // borrow. The callee never reads `self.jsx_imports`, so the take/restore is
-            // semantically a no-op.
-            let import_source: &'a [u8] = p.arena.alloc_slice_copy(p.options.jsx.import_source());
-            let package_name: &'a [u8] = p.arena.alloc_slice_copy(&p.options.jsx.package_name);
+            // Taken out, and put back below, so that `generate_import_stmt` can borrow `p` mutably.
             let jsx_imports = core::mem::take(&mut p.jsx_imports);
 
             let mut buf: [&'static [u8]; 3] = [b"", b"", b""];
             let runtime_import_names = jsx_imports.runtime_import_names(&mut buf);
 
             if !runtime_import_names.is_empty() {
+                // Copied here, not above: a parse with no JSX element allocates nothing.
+                let import_source: &'a [u8] =
+                    p.arena.alloc_slice_copy(p.options.jsx.import_source());
                 p.generate_import_stmt(
                     import_source,
                     runtime_import_names,
@@ -2308,6 +2304,7 @@ impl<'a> Parser<'a> {
 
             let source_import_names = jsx_imports.source_import_names();
             if !source_import_names.is_empty() {
+                let package_name: &'a [u8] = p.arena.alloc_slice_copy(&p.options.jsx.package_name);
                 p.generate_import_stmt(
                     package_name,
                     source_import_names,

src/runtime/cli/repl.rs

@@ -2148,6 +2148,8 @@ impl<'a> Repl<'a> {
         opts.repl_mode = true;
         opts.features.dead_code_elimination = false; // REPL needs all code
         opts.features.top_level_await = true; // Enable top-level await in REPL
+        // Without the import, automatic-runtime JSX calls a name that nothing declares.
+        opts.features.auto_import_jsx = vm.transpiler.options.auto_import_jsx;
         // Keep `lower_using` at its default (true) here even though JavaScriptCore
         // supports `using` / `await using` natively. The REPL transform in
         // `js_parser/repl_transforms.rs` rewrites every top-level `s_local` into a