From cb037e681757bca53544434eef393f11fc734f3a Mon Sep 17 00:00:00 2001
From: Mark Dalgleish <mark.john.dalgleish@gmail.com>
Date: Wed, 2 Oct 2024 16:12:16 +1000
Subject: [PATCH] Support shared imports in route chunks

---
 .../vite/route-chunks-test.ts                 | 20 +++++++++
 .../react-router-dev/vite/route-chunks.ts     | 41 ++++---------------
 2 files changed, 29 insertions(+), 32 deletions(-)

diff --git a/packages/react-router-dev/vite/route-chunks-test.ts b/packages/react-router-dev/vite/route-chunks-test.ts
index 93ce850f33..17dc9f280c 100644
--- a/packages/react-router-dev/vite/route-chunks-test.ts
+++ b/packages/react-router-dev/vite/route-chunks-test.ts
@@ -165,6 +165,26 @@ describe("route chunks", () => {
       `);
     });
 
+    test("shared imports", () => {
+      const code = dedent`
+        import { shared } from "./shared";
+        export const chunk = shared("chunk");
+        export const main = shared("main");
+      `;
+      expect(hasChunkableExport(code, "chunk", ...cache)).toBe(true);
+      expect(hasChunkableExport(code, "main", ...cache)).toBe(true);
+      expect(getChunkedExport(code, "chunk", {}, ...cache)?.code)
+        .toMatchInlineSnapshot(`
+        "import { shared } from "./shared";
+        export const chunk = shared("chunk");"
+      `);
+      expect(getChunkedExport(code, "main", {}, ...cache)?.code)
+        .toMatchInlineSnapshot(`
+        "import { shared } from "./shared";
+        export const main = shared("main");"
+      `);
+    });
+
     test("re-exports using shared statement", () => {
       const code = dedent`
         export { chunk1, chunk2, main } from "./shared";
diff --git a/packages/react-router-dev/vite/route-chunks.ts b/packages/react-router-dev/vite/route-chunks.ts
index 810bb735f2..058d737de2 100644
--- a/packages/react-router-dev/vite/route-chunks.ts
+++ b/packages/react-router-dev/vite/route-chunks.ts
@@ -53,6 +53,7 @@ function assertNodePathIsStatement(
     }`
   );
 }
+
 function assertNodePathIsVariableDeclarator(
   path: NodePath | NodePath[] | null | undefined
 ): asserts path is NodePath<VariableDeclarator> {
@@ -469,11 +470,6 @@ export function hasChunkableExport(
         return false;
       }
 
-      invariant(
-        dependencies.topLevelStatements.size > 0,
-        `Expected export "${exportName}" to have top level statements if the set exists`
-      );
-
       // Loop through all other exports to see if they have top level non-import
       // statements in common with the export we're trying to chunk.
       for (let [currentExportName, currentDependencies] of exportDependencies) {
@@ -498,35 +494,16 @@ export function hasChunkableExport(
         }
       }
 
-      // Loop through all other exports to see if they have imported identifiers
-      // in common with the export we're trying to chunk.
-      if (dependencies.importedIdentifierNames.size > 0) {
-        for (let [
-          currentExportName,
-          currentDependencies,
-        ] of exportDependencies) {
-          if (currentExportName === exportName) {
-            continue;
-          }
-
-          // As soon as we find any imported identifiers in common with another
-          // export, we know this export cannot be placed in its own chunk. Note
-          // that the chunk can still share top level import statements with
-          // other exports because we filter out all unused imports, so we can
-          // treat each imported identifier as a separate entity in this check.
-          if (
-            setsIntersect(
-              currentDependencies.importedIdentifierNames,
-              dependencies.importedIdentifierNames
-            )
-          ) {
-            return false;
-          }
-        }
+      // If the export we're trying to chunk depends on more than one exported
+      // variable declarator (where one of them might be the chunked export
+      // itself), it means it must depend on other exports and can't be chunked,
+      // so we can bail out early before comparing against other exports.
+      if (dependencies.exportedVariableDeclarators.size > 1) {
+        return false;
       }
 
-      // Loop through all other exports to see if they have exported variable
-      // declarators in common with the export we're trying to chunk.
+      // Loop through all other exports to see if they depend on the export
+      // we're trying to chunk.
       if (dependencies.exportedVariableDeclarators.size > 0) {
         for (let [
           currentExportName,