fix(v1-route-convention): allow sibling pathless layout routes

.changeset/sibling-pathless-routes.md

@@ -0,0 +1,5 @@
+---
+"@remix-run/v1-route-convention": patch
+---
+
+Allow sibling pathless layout routes (from https://github.com/remix-run/remix/pull/4421)

packages/v1-route-convention/__tests__/index-test.ts

@@ -150,4 +150,92 @@ describe("defineConventionalRoutes", () => {
 
     expect(routes).toMatchObject(expected);
   });
+
+  it("supports sibling pathless layout routes", () => {
+    let routes = createRoutesFromFolders(defineRoutes, {
+      appDirectory: path.join(
+        __dirname,
+        "fixtures",
+        "sibling-pathless-layout-routes"
+      ),
+    });
+
+    expect(routes).toEqual({
+      "routes/__a": {
+        file: path.join("routes", "__a.tsx"),
+        id: "routes/__a",
+        parentId: "root",
+      },
+      "routes/__a/a": {
+        file: path.join("routes", "__a", "a.tsx"),
+        id: "routes/__a/a",
+        parentId: "routes/__a",
+        path: "a",
+      },
+      "routes/__a/index": {
+        file: path.join("routes", "__a", "index.tsx"),
+        id: "routes/__a/index",
+        index: true,
+        parentId: "routes/__a",
+      },
+      "routes/__b": {
+        file: path.join("routes", "__b.tsx"),
+        id: "routes/__b",
+        parentId: "root",
+      },
+      "routes/__b/b": {
+        caseSensitive: undefined,
+        file: path.join("routes", "__b", "b.tsx"),
+        id: "routes/__b/b",
+        index: undefined,
+        parentId: "routes/__b",
+        path: "b",
+      },
+    });
+  });
+
+  // See: https://github.com/remix-run/remix/discussions/3014
+  it("handles sibling pathless and index routes", () => {
+    let routes = createRoutesFromFolders(defineRoutes, {
+      appDirectory: path.join(__dirname, "fixtures", "blog-collision"),
+    });
+
+    expect(routes).toEqual({
+      "routes/blog/__nested": {
+        file: path.join("routes", "blog", "__nested.tsx"),
+        id: "routes/blog/__nested",
+        parentId: "root",
+        path: "blog",
+      },
+      "routes/blog/__nested/new": {
+        file: path.join("routes", "blog", "__nested", "new.tsx"),
+        id: "routes/blog/__nested/new",
+        parentId: "routes/blog/__nested",
+        path: "new",
+      },
+      "routes/blog/index": {
+        file: path.join("routes", "blog", "index.tsx"),
+        id: "routes/blog/index",
+        index: true,
+        parentId: "root",
+        path: "blog",
+      },
+      "routes/index": {
+        file: path.join("routes", "index.tsx"),
+        id: "routes/index",
+        index: true,
+        parentId: "root",
+      },
+    });
+  });
+
+  it("warns on route collisions", () => {
+    expect(() =>
+      createRoutesFromFolders(defineRoutes, {
+        appDirectory: path.join(__dirname, "fixtures", "route-collisions"),
+      })
+    ).toThrowErrorMatchingInlineSnapshot(
+      '"Path \\"a\\" defined by route \\"routes/__b/a\\" conflicts with route \\"routes/__a/a\\""'
+    );
+  });
 });

packages/v1-route-convention/src/lib.ts

@@ -105,15 +105,52 @@ export function createRoutesFromFolders(
       let isIndexRoute = routeId.endsWith("/index");
       let fullPath = createRoutePath(routeId.slice(routesDirectory.length + 1));
       let uniqueRouteId = (fullPath || "") + (isIndexRoute ? "?index" : "");
-
-      if (uniqueRouteId) {
+      let isPathlessLayoutRoute =
+        routeId.split("/").pop()?.startsWith("__") === true;
+
+      /**
+       * We do not try to detect path collisions for pathless layout route
+       * files because, by definition, they create the potential for route
+       * collisions _at that level in the tree_.
+       *
+       * Consider example where a user may want multiple pathless layout routes
+       * for different subfolders
+       *
+       *   routes/
+       *     account.tsx
+       *     account/
+       *       __public/
+       *         login.tsx
+       *         perks.tsx
+       *       __private/
+       *         orders.tsx
+       *         profile.tsx
+       *       __public.tsx
+       *       __private.tsx
+       *
+       * In order to support both a public and private layout for `/account/*`
+       * URLs, we are creating a mutually exclusive set of URLs beneath 2
+       * separate pathless layout routes.  In this case, the route paths for
+       * both account/__public.tsx and account/__private.tsx is the same
+       * (/account), but we're again not expecting to match at that level.
+       *
+       * By only ignoring this check when the final portion of the filename is
+       * pathless, we will still detect path collisions such as:
+       *
+       *   routes/parent/__pathless/foo.tsx
+       *   routes/parent/__pathless2/foo.tsx
+       *
+       * and
+       *
+       *   routes/parent/__pathless/index.tsx
+       *   routes/parent/__pathless2/index.tsx
+       */
+      if (uniqueRouteId && !isPathlessLayoutRoute) {
         if (uniqueRoutes.has(uniqueRouteId)) {
           throw new Error(
-            `Path ${JSON.stringify(fullPath)} defined by route ${JSON.stringify(
-              routeId
-            )} conflicts with route ${JSON.stringify(
-              uniqueRoutes.get(uniqueRouteId)
-            )}`
+            `Path ${JSON.stringify(fullPath || "/")} defined by route ` +
+              `${JSON.stringify(routeId)} conflicts with route ` +
+              `${JSON.stringify(uniqueRoutes.get(uniqueRouteId))}`
           );
         } else {
           uniqueRoutes.set(uniqueRouteId, routeId);
@@ -268,6 +305,8 @@ export function createRoutePath(partialRouteId: string): string | undefined {
 
   if (rawSegmentBuffer === "index" && result.endsWith("index")) {
     result = result.replace(/\/?index$/, "");
+  } else {
+    result = result.replace(/\/$/, "");
   }
 
   if (rawSegmentBuffer === "index" && result.endsWith("index?")) {