[Bug]: Build error occurred after upgrading @rslib/core from version 0.18.4 to 0.18.5

[AlaDouagi]

Version

System:
    OS: Windows 11 10.0.22631
    CPU: (14) x64 Intel(R) Core(TM) Ultra 7 165U
    Memory: 15.78 GB / 31.43 GB
  Browsers:
    Chrome: 142.0.7444.177
    Edge: Chromium (140.0.3485.54)
    Firefox: 140.6.0 - C:\Program Files\Mozilla Firefox\firefox.exe
    Internet Explorer: 11.0.22621.3527
  npmPackages:
    @rslib/core: ^0.18.5 => 0.18.5

Details

By only upgrading to the new patch version from 0.18.4 to 0.18.5, the build error appeared for my project

> rslib mf-dev

  Rslib v0.18.5

start   build started...
Federated types created correctly
Federated mocks created correctly
error   Build errors: 
× Prevent writing to file that only differs in casing or query string from already written file.
  │ This will lead to a race-condition and corrupted files on case-insensitive file systems.
  │   - alert.js.map
  │   - Alert.js.map

× Prevent writing to file that only differs in casing or query string from already written file.
  │ This will lead to a race-condition and corrupted files on case-insensitive file systems.
  │   - alert.js
  │   - Alert.js

error   build failed in 3.75 s

Reproduce link

https://codepen.io/Justineo/pen/yLbxxOR

Reproduce Steps

For this rslib.config.ts, a Module Federation entry file with the same characters but one is Alert (capitalized), and the other is alert (lowercase), started to suddenly break the build:

import { resolve } from "node:path";

import { NativeFederationTestsRemote } from "@module-federation/native-federation-tests/rspack";
import { NativeFederationTypeScriptRemote } from "@module-federation/native-federation-typescript/rspack";
import { pluginModuleFederation } from "@module-federation/rsbuild-plugin";
import { pluginReact } from "@rsbuild/plugin-react";
import { defineConfig } from "@rslib/core";

const peerDependencies = require("./package.json").peerDependencies;

const moduleFederationConfig = {
  name: "my_library",
  exposes: {
    "./components/Alert": "./src/components/Alert",
    "./shadcn/ui/alert": "./src/shadcn/ui/alert",
  },
  shared: {
    react: {
      requiredVersion: peerDependencies.react,
      singleton: true,
      eager: true,
    },
    "react-dom": {
      requiredVersion: peerDependencies["react-dom"],
      singleton: true,
      eager: true,
    },
  },
};

export default defineConfig({
  resolve: {
    alias: {
      "@/shadcn": resolve(__dirname, "./src/shadcn"),
    },
  },
  lib: [
    {
      format: "mf",
      source: {
        entry: {
          Alert: "./src/components/Alert.tsx",
          alert: "./src/shadcn/ui/alert.tsx",
        },
      },
      output: {
        target: "web",
        assetPrefix: "auto",
      },
      dev: {
        assetPrefix: undefined,
        lazyCompilation: false,
      },
      plugins: [pluginModuleFederation(moduleFederationConfig, {})],
    },
  ],
  tools: {
    rspack: {
      plugins: [
        NativeFederationTypeScriptRemote({ moduleFederationConfig }),
        NativeFederationTestsRemote({
          moduleFederationConfig,
          additionalBundlerConfig: { format: "esm" },
        }),
      ],
      lazyCompilation: false,
    },
  },
  source: {
    tsconfigPath: "./tsconfig.build.json",
  },
  server: {
    port: 3000,
  },
  plugins: [pluginReact()],
});

PS: The Alert files are simple React files with .tsx extension.

[chenjiahan]

Related PR: web-infra-dev/rspack#12462

@LingyuCoder cc

[Timeless0911]

We would like to apologize for any inconvenience this may cause. A recent update has introduced case‑sensitive conflict detection during asset emission to prevent race conditions and file corruption on case-insensitive file systems as same as webpack.

For further details, you may refer to the corresponding PR description.

If your project includes assets whose filenames differ only in letter casing (e.g., alert.js and Alert.js), you may now encounter an error before files are written. To proceed, you can rename the affected files so that their names are distinct even when case is ignored.

Thank you for your understanding and we apologize again for the disruption.

[AlaDouagi]

Thanks for the response, @Timeless0911 .
However, I don’t think renaming files to work around this NEW issue is a good solution. In the example above, the two source files are located in different paths, and after running the build they will be emitted with different hashed filenames in the ./dist folder. This behavior is expected, and there’s nothing wrong with the configuration when two files share the same name but live in different directories.
Introducing an error or warning here feels like an unnecessary limitation. I want to expose two versions of the alert component—one using MUI and the other using Shadcn. Specifying two different paths with the same filename is a natural use case and shouldn’t trigger any errors or warnings.

[Timeless0911]

after running the build they will be emitted with different hashed filenames in the ./dist folder.

This check should be based on the final output path. If it contains a hash, it shouldn't trigger this check.

mf-dev is in development mode, so the output filename does not contains a hash by default, emit alert.js and Alert.js in same final output folder may lead to a race-condition and corrupted files on case-insensitive file systems.

In build mode, the output filename contains a hash by default so this usage is natural.

You can add a filename hash in dev mode as a workaround temporarily, see https://rsbuild.rs/config/output/filename. We will discuss about this check recently.

[AlaDouagi]

@Timeless0911 Currently, there’s no straightforward way to enable content hashing for the Rslib dev server. I had to modify the configuration file in a more complex manner to make dev mode work. Initially, I assumed this could be achieved with a simple boolean flag, here is what I had to do to bypass this new issue:

import { resolve } from "node:path";

import { NativeFederationTestsRemote } from "@module-federation/native-federation-tests/rspack";
import { NativeFederationTypeScriptRemote } from "@module-federation/native-federation-typescript/rspack";
import { pluginModuleFederation } from "@module-federation/rsbuild-plugin";
import { pluginReact } from "@rsbuild/plugin-react";
import { defineConfig } from "@rslib/core";

const peerDependencies = require("./package.json").peerDependencies;

const moduleFederationConfig = {
  name: "my_library",
  exposes: {
    "./components/Alert": "./src/components/Alert",
    "./shadcn/ui/alert": "./src/shadcn/ui/alert",
  },
  shared: {
    react: {
      requiredVersion: peerDependencies.react,
      singleton: true,
      eager: true,
    },
    "react-dom": {
      requiredVersion: peerDependencies["react-dom"],
      singleton: true,
      eager: true,
    },
  },
};

+const prodDefaultFilename = {
+  html: "[name].html",
+  js: "[name].[contenthash:8].js",
+  css: "[name].[contenthash:8].css",
+  svg: "[name].[contenthash:8].svg",
+  font: "[name].[contenthash:8][ext]",
+  wasm: "[contenthash:8].module.wasm",
+  image: "[name].[contenthash:8][ext]",
+  media: "[name].[contenthash:8][ext]",
+  assets: "[name].[contenthash:8][ext]",
+};

export default defineConfig({
  resolve: {
    alias: {
      "@/shadcn": resolve(__dirname, "./src/shadcn"),
    },
  },
  lib: [
    {
      format: "mf",
      source: {
        entry: {
          Alert: "./src/components/Alert.tsx",
          alert: "./src/shadcn/ui/alert.tsx",
        },
      },
      output: {
        target: "web",
        assetPrefix: "auto",
+      filenameHash: true,
+      filename: prodDefaultFilename,
      },
      dev: {
        assetPrefix: undefined,
        lazyCompilation: false,
      },
      plugins: [pluginModuleFederation(moduleFederationConfig, {})],
    },
  ],
  tools: {
    rspack: {
      plugins: [
        NativeFederationTypeScriptRemote({ moduleFederationConfig }),
        NativeFederationTestsRemote({
          moduleFederationConfig,
          additionalBundlerConfig: { format: "esm" },
        }),
      ],
      lazyCompilation: false,
    },
  },
  source: {
    tsconfigPath: "./tsconfig.build.json",
  },
  server: {
    port: 3000,
  },
  plugins: [pluginReact()],
});

Maybe a new dev.filenameHash ?: boolean property to enable dev server hashing could be a great feature.

[Timeless0911]

In fact, add content hash in dev mode is quite not a good practice.

And we have refactored this check in web-infra-dev/rspack#12532 to make it enabled by adding a plugin with warning log.

Rslib will bump Rspack version and release a new version in recent one or two days. The only thing you need to do to fix this issue is bumping Rslib version.

[Timeless0911]

Sorry, this fix should be shipped in next week's Rspack release, please stay tuned. I will close the issue and notify you after it is fixed.