wip

packages/react-router-dev/package.json

@@ -32,6 +32,7 @@
     "@npmcli/package-json": "^4.0.1",
     "@react-router/node": "workspace:*",
     "arg": "^5.0.1",
+    "babel-dead-code-elimination": "^1.0.6",
     "chalk": "^4.1.2",
     "es-module-lexer": "^1.3.1",
     "exit-hook": "2.2.1",

packages/react-router-dev/vite/define-route.ts

@@ -1,17 +1,39 @@
 import * as babel from "@babel/core";
 import type { Binding, NodePath } from "@babel/traverse";
-
-import { parse as _parse, t, traverse } from "./babel";
 import type { ParseResult } from "@babel/parser";
+import {
+  deadCodeElimination,
+  findReferencedIdentifiers,
+} from "babel-dead-code-elimination";
+
+import { generate, parse as _parse, t, traverse } from "./babel";
+
+export function transform(
+  code: string,
+  id: string,
+  options: { ssr?: boolean } = {}
+) {
+  if (options?.ssr) return code;
 
-export function transform(code: string) {
   let ast = parse(code);
+  let refs = findReferencedIdentifiers(ast);
+
+  let markedForRemoval: NodePath<t.Node>[] = [];
   assertDefineRouteOnlyAfterExportDefault(ast);
   traverse(ast, {
     ExportDefaultDeclaration(path) {
-      analyzeRouteExport(path);
+      let analysis = analyzeRouteExport(path);
+      for (let [key, fieldPath] of Object.entries(analysis)) {
+        if (["headers", "serverLoader", "serverAction"].includes(key)) {
+          if (!fieldPath) continue;
+          markedForRemoval.push(fieldPath);
+        }
+      }
     },
   });
+  markedForRemoval.forEach((path) => path.remove());
+  deadCodeElimination(ast, refs);
+  return generate(ast, { sourceMaps: true, sourceFileName: id }, code);
 }
 
 export function parseFields(code: string): string[] {

packages/react-router-dev/vite/plugin.ts

@@ -1326,6 +1326,7 @@ export const reactRouterVitePlugin: ReactRouterVitePlugin = (_config) => {
       enforce: "pre",
       async transform(code, id, options) {
         if (options?.ssr) return;
+        if (!code.includes("defineRoute")) return; // temporary back compat, remove once old style routes are unsupported
 
         if (id.endsWith(ROUTE_ENTRY_QUERY_STRING)) return;
 
@@ -1334,8 +1335,7 @@ export const reactRouterVitePlugin: ReactRouterVitePlugin = (_config) => {
           return defineRoute.assertNotImported(code);
         }
 
-        if (!code.includes("defineRoute")) return; // temporary back compat, remove once old style routes are unsupported
-        defineRoute.transform(code);
+        return defineRoute.transform(code, id, options);
       },
     },
     {