fix: do not split root module for async chunks

crates/mako/src/optimize_chunk.rs

@@ -185,17 +185,32 @@ impl Compiler {
     ) {
         let chunk_graph = self.context.chunk_graph.read().unwrap();
         let chunks = chunk_graph.get_all_chunks();
+        let async_chunk_root_modules = chunks
+            .iter()
+            .filter_map(|chunk| match chunk.chunk_type {
+                ChunkType::Async => chunk.modules.last(),
+                _ => None,
+            })
+            .collect::<Vec<_>>();
         let modules_in_chunk = match modules_in_chunk {
             Some(modules_in_chunk) => modules_in_chunk,
             None => chunks.iter().fold(vec![], |mut acc, chunk| {
                 acc.append(
                     &mut chunk
                         .modules
                         .iter()
-                        .filter_map(|m| match &chunk.chunk_type {
-                            // entry module of entry chunk should not be optimized
-                            ChunkType::Entry(entry_id, _, false) if m.id == entry_id.id => None,
-                            _ => Some((m, &chunk.id, &chunk.chunk_type)),
+                        .filter_map(|m| {
+                            match (&chunk.chunk_type, async_chunk_root_modules.contains(&m)) {
+                                // async chunk root module should not be optimized
+                                (_, true) => None,
+                                // entry module of entry chunk should not be optimized
+                                (ChunkType::Entry(entry_id, _, false), _)
+                                    if m.id == entry_id.id =>
+                                {
+                                    None
+                                }
+                                _ => Some((m, &chunk.id, &chunk.chunk_type)),
+                            }
                         })
                         .collect::<Vec<_>>(),
                 );

e2e/fixtures/code-splitting.complex/expect.js

@@ -49,20 +49,10 @@ assert.match(
   "should ensure splitting dependent chunks on demand (not-full)"
 );
 
-assert.match(
+assert.doesNotMatch(
   files["common-async.js"],
-  moduleReg("src/should-be-common.ts", "tooLongText"),
-  "should merge common async chunk to common chunk"
-);
-
-assert.match(
-  files["index.js"].replace(/\s/g, ""),
-  new RegExp(`Promise.all\\(\\[${
-    [
-      "common"
-    ].map((f) => `__mako_require__.ensure\\("${f}"\\)`).join(",")
-  }\\]\\).then\\(__mako_require__.bind\\(__mako_require__,"src\\/should-be-common.ts"\\)\\)`),
-  "should load merged common async chunk with common chunk and without self"
+  moduleReg("src/should-not-be-common.ts", "tooLongText"),
+  "should not merge common async chunk to common chunk"
 );
 
 assert(

e2e/fixtures/code-splitting.complex/src/index.ts

@@ -4,6 +4,6 @@ import Button from 'antd/es/button';
 console.log(React, Button);
 
 import('./should-be-split').then((m) => console.log(m));
-import('./should-be-common').then((m) => console.log(m));
+import('./should-not-be-common').then((m) => console.log(m));
 import('./should-be-merged').then((m) => console.log(m));
 import('./other-dynamic').then((m) => console.log(m));

e2e/fixtures/code-splitting.complex/src/should-be-split.ts

@@ -9,7 +9,7 @@ import * as icons from '@ant-design/icons';
 import context from './context';
 import common from './common';
 // make sure `should-be-split-self` has 2+ parents
-import other from './should-be-common';
+import other from './should-not-be-common';
 
 console.log(React, ReactDOM, less, overlay, refresh, antd, icons, context, common, other);