fix(core): fix codegen routesChunkName possible hash collision

packages/docusaurus/src/server/codegen/__tests__/codegenRoutes.test.ts

@@ -5,13 +5,18 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import {fromPartial} from '@total-typescript/shoehorn';
 import {
   generateRoutesCode,
   genChunkName,
   generateRoutePropFilename,
 } from '../codegenRoutes';
 import type {RouteConfig} from '@docusaurus/types';
 
+function route(routeConfig: Partial<RouteConfig>): RouteConfig {
+  return fromPartial(routeConfig);
+}
+
 describe('generateRoutePropFilename', () => {
   it('generate filename based on route path', () => {
     expect(
@@ -206,9 +211,7 @@ describe('loadRoutes', () => {
         },
       ],
     };
-    expect(
-      generateRoutesCode([nestedRouteConfig], '/', 'ignore'),
-    ).toMatchSnapshot();
+    expect(generateRoutesCode([nestedRouteConfig])).toMatchSnapshot();
   });
 
   it('loads flat route config', () => {
@@ -243,17 +246,15 @@ describe('loadRoutes', () => {
         ],
       },
     };
-    expect(
-      generateRoutesCode([flatRouteConfig], '/', 'ignore'),
-    ).toMatchSnapshot();
+    expect(generateRoutesCode([flatRouteConfig])).toMatchSnapshot();
   });
 
   it('rejects invalid route config', () => {
     const routeConfigWithoutPath = {
       component: 'hello/world.js',
     } as RouteConfig;
 
-    expect(() => generateRoutesCode([routeConfigWithoutPath], '/', 'ignore'))
+    expect(() => generateRoutesCode([routeConfigWithoutPath]))
       .toThrowErrorMatchingInlineSnapshot(`
       "Invalid route config: path must be a string and component is required.
       {"component":"hello/world.js"}"
@@ -263,9 +264,8 @@ describe('loadRoutes', () => {
       path: '/hello/world',
     } as RouteConfig;
 
-    expect(() =>
-      generateRoutesCode([routeConfigWithoutComponent], '/', 'ignore'),
-    ).toThrowErrorMatchingInlineSnapshot(`
+    expect(() => generateRoutesCode([routeConfigWithoutComponent]))
+      .toThrowErrorMatchingInlineSnapshot(`
       "Invalid route config: path must be a string and component is required.
       {"path":"/hello/world"}"
     `);
@@ -277,6 +277,56 @@ describe('loadRoutes', () => {
       component: 'hello/world.js',
     } as RouteConfig;
 
-    expect(generateRoutesCode([routeConfig], '/', 'ignore')).toMatchSnapshot();
+    expect(generateRoutesCode([routeConfig])).toMatchSnapshot();
+  });
+
+  it('generates an entry for each route and handle hash collisions', () => {
+    // See bug https://github.com/facebook/docusaurus/issues/10718#issuecomment-2507635907
+    const routeConfigs = [
+      route({
+        path: '/docs',
+        component: '@theme/Root',
+        routes: [
+          route({
+            path: '/docs',
+            component: '@theme/Version',
+            children: [],
+          }),
+        ],
+      }),
+      route({
+        path: '/docs',
+        component: '@theme/Root',
+        routes: [
+          route({
+            path: '/docs',
+            component: '@theme/Version',
+            children: [],
+          }),
+        ],
+      }),
+    ];
+
+    const result = generateRoutesCode(routeConfigs);
+
+    // We absolutely want to have 2 entries here, even if routes are the same
+    // One should not override the other
+    expect(Object.keys(result.routesChunkNames)).toHaveLength(4);
+    expect(result.routesChunkNames).toMatchInlineSnapshot(`
+      {
+        "/docs-611": {
+          "__comp": "__comp---theme-version-6-f-8-19f",
+        },
+        "/docs-96a": {
+          "__comp": "__comp---theme-root-1-dd-d3a",
+        },
+        "/docs-d3d": {
+          "__comp": "__comp---theme-version-6-f-8-19f",
+        },
+        "/docs-e4f": {
+          "__comp": "__comp---theme-root-1-dd-d3a",
+        },
+      }
+    `);
   });
 });

packages/docusaurus/src/server/codegen/codegenRoutes.ts

@@ -194,7 +194,12 @@ function genChunkNames(
  * config node, it returns the node's serialized form, and mutates `registry`,
  * `routesPaths`, and `routesChunkNames` accordingly.
  */
-function genRouteCode(routeConfig: RouteConfig, res: RoutesCode): string {
+function genRouteCode(
+  routeConfig: RouteConfig,
+  res: RoutesCode,
+  index: number,
+  level: number,
+): string {
   const {
     path: routePath,
     component,
@@ -216,8 +221,39 @@ ${JSON.stringify(routeConfig)}`,
     );
   }
 
-  const routeHash = simpleHash(JSON.stringify(routeConfig), 3);
-  res.routesChunkNames[`${routePath}-${routeHash}`] = {
+  // Because 2 routes with the same path could lead to hash collisions
+  // See https://github.com/facebook/docusaurus/issues/10718#issuecomment-2498516394
+  function generateUniqueRouteKey(): {
+    routeKey: string;
+    routeHash: string;
+  } {
+    const hashes = [
+      // // OG algo to keep former snapshots
+      () => simpleHash(JSON.stringify(routeConfig), 3),
+      // Other attempts, not ideal but good enough
+      // Technically we could use Math.random() here but it's annoying for tests
+      () => simpleHash(`${level}${index}`, 3),
+      () => simpleHash(JSON.stringify(routeConfig), 4),
+      () => simpleHash(`${level}${index}`, 4),
+    ];
+
+    for (const tryHash of hashes) {
+      const routeHash = tryHash();
+      const routeKey = `${routePath}-${routeHash}`;
+      if (!res.routesChunkNames[routeKey]) {
+        return {routeKey, routeHash};
+      }
+    }
+    throw new Error(
+      `Docusaurus couldn't generate a unique hash for route ${routeConfig.path} (level=${level} - index=${index}).
+This is a bug, please report it here!
+https://github.com/facebook/docusaurus/issues/10718`,
+    );
+  }
+
+  const {routeKey, routeHash} = generateUniqueRouteKey();
+
+  res.routesChunkNames[routeKey] = {
     // Avoid clash with a prop called "component"
     ...genChunkNames({__comp: component}, 'component', component, res),
     ...(context &&
@@ -228,7 +264,9 @@ ${JSON.stringify(routeConfig)}`,
   return serializeRouteConfig({
     routePath: routePath.replace(/'/g, "\\'"),
     routeHash,
-    subroutesCodeStrings: subroutes?.map((r) => genRouteCode(r, res)),
+    subroutesCodeStrings: subroutes?.map((r, i) =>
+      genRouteCode(r, res, i, level + 1),
+    ),
     exact,
     attributes,
   });
@@ -253,7 +291,7 @@ export function generateRoutesCode(routeConfigs: RouteConfig[]): RoutesCode {
 
   // `genRouteCode` would mutate `res`
   const routeConfigSerialized = routeConfigs
-    .map((r) => genRouteCode(r, res))
+    .map((r, i) => genRouteCode(r, res, i, 0))
     .join(',\n');
 
   res.routesConfig = `import React from 'react';