Angular-cli: WARNING in Conflict: Multiple assets emit different content to the same filename 3rdpartylicenses.txt

[filipesilva]

🐞 Bug report

Command (mark with an x)

• [ ] new
• [ ] build
• [ ] serve
• [ ] test
• [ ] e2e
• [ ] generate
• [ ] add
• [ ] update
• [ ] lint
• [ ] xi18n
• [ ] run
• [ ] config
• [ ] help
• [ ] version
• [ ] doc

Is this a regression?

Yes, the previous version in which this bug was not present was: .8.x

Description

The following warning appears on production builds:

kamik@RED-X1C6 MINGW64 /d/sandbox/super-productivity (update-9)
$ yarn buildFrontend --output-path dist-ivy
yarn run v1.17.3
$ node --max_old_space_size=4096 ./node_modules/@angular/cli/bin/ng build --aot --prod --output-path dist-ivy
69% building 889/891 modules 2 active ....js??ref--18-0!D:\sandbox\super-productivity\node_modules\@ngtools\webpack\src\index.js!D:\sandbox\super-productivity\src\app\core\compression\lz.worker.ts 69% building 1154/1157 modules 3 active ...-18-0!D:\sandbox\super-productivity\node_modules\@ngtools\webpack\src\index.js!D:\sandbox\super-productivity\src\app\features\reminder\reminder.worker.ts 
chunk {0} runtime.0f9d2f90a0d2148a4e14.js, runtime.0f9d2f90a0d2148a4e14.js.map (runtime) 1.51 kB [entry] [rendered]
chunk {1} main.9009a33894da809485f9.js, main.9009a33894da809485f9.js.map (main) 3.33 MB [initial] [rendered]
chunk {2} polyfills.75f8db4dd1e518a7835b.js, polyfills.75f8db4dd1e518a7835b.js.map (polyfills) 121 kB [initial] [rendered]
chunk {3} polyfills-es5.aca657e0425e42bebda6.js, polyfills-es5.aca657e0425e42bebda6.js.map (polyfills-es5) 201 kB [initial] [rendered]
chunk {4} styles.c5a09efce74a2a2c2e94.css, styles.c5a09efce74a2a2c2e94.css.map (styles) 167 kB [initial] [rendered]
Date: 2019-11-14T13:28:02.212Z - Hash: c21370451102fb263dbb - Time: 154136ms

WARNING in Conflict: Multiple assets emit different content to the same filename 3rdpartylicenses.txt
Done in 165.04s.

🔬 Minimal Reproduction

• clone https://github.com/johannesjo/super-productivity
• update to latest CLI, FW, and Material
• add the following ngcc.onfig.js

module.exports = {
  packages: {
    'angular2-promise-buttons': {
      entryPoints: { '.': { override: {module: undefined} } }
    }
  }
};

• build with either Ivy oe VE

🔥 Exception or Error

WARNING in Conflict: Multiple assets emit different content to the same filename 3rdpartylicenses.txt

🌍 Your Environment

Angular CLI: 9.0.0-rc.2
Node: 10.16.0
OS: win32 x64
Angular: 9.0.0-rc.2
... animations, cli, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... platform-server, router, service-worker

Package                            Version
------------------------------------------------------------
@angular-devkit/architect          0.900.0-rc.2
@angular-devkit/build-angular      0.900.0-rc.2
@angular-devkit/build-optimizer    0.900.0-rc.2
@angular-devkit/build-webpack      0.900.0-rc.2
@angular-devkit/core               9.0.0-rc.2
@angular-devkit/schematics         9.0.0-rc.2
@angular/cdk                       9.0.0-rc.1
@angular/material                  9.0.0-rc.1
@angular/material-moment-adapter   9.0.0-rc.1
@ngtools/webpack                   9.0.0-rc.2
@schematics/angular                8.3.8
@schematics/update                 0.900.0-rc.2
rxjs                               6.5.3
typescript                         3.6.4
webpack                            4.41.2

[dgp1130]

From @clydin:

The LicenseWebpackPlugin (https://github.com/xz64/license-webpack-plugin) emits the 3rdpartylicenses.txt file. The plugin uses the webpack compilation hook optimizeChunkAssetwhich can be called multiple times within a single compilation. (code: https://github.com/xz64/license-webpack-plugin/blob/master/src/WebpackCompilerHandler.ts#L27) This is the source of the multiple license assets. One case of this hook being called multiple times is the presence of stylesheets within the projects styles option. The MiniCssExtractPlugin used to output the CSS appears to call the hook while extracting the stylesheets from the internal webpack javascript variant of the stylesheet.

The emit hook would most likely be the more appropriate hook to use as this is called once at the completion of the compilation to output the files. This would necessitate a change to the plugin itself which is third-party.

An alternative could be to switch plugins to https://github.com/microsoft/license-checker-webpack-plugin which uses the emit hook.

The most obvious fix would be to update license-webpack-plugin to use the emit hook, however this could have ripple effects for the rest of the repo. Even if we fix the problem there, it may take some time for a stable release which we can depend on, which likely won't make the v9 release timeframe.

The other option would be to switch to Microsoft's license-checker-webpack-plugin, though this is probably more overall effort and would probably make google3 integration harder (Edit: @angular-devkit/build-angular is not included in the g3 build pipeline).

[dgp1130]

After some discussion, we decided that changing a dependency like this so close to the v9 launch was a little to risky. Instead, we chose to filter out this particular warning message for v9 and then follow up with a proper fix in a 9.x release.

PR to suppress the warning: https://github.com/angular/angular-cli/pull/16349

Given the extra time we will also have the option to choose whether we want to replace the whole dependency or take the time to actually fix the underlying problem.

[dgp1130]

Warning was suppressed by #16349, so this is no longer a regression. Will need to follow up later with a proper fix.

[amjadkhanroot]

This bug also appears in angular 8.x.
See the screenshot below.

[dgp1130]

Hmm, thanks for bringing this up. The fix PR was marked to be merged to the patch branch, but I don't see it in the 8.3.x branch. Likely the caretaker just missed it at the time. I'll ask the caretaker to merge this in.

[dgp1130]

Actually @clydin, pointed out that I was confusing the meaning of "patch". It was correctly patched to the 9.0.x branch. 8.3.x is the LTS branch where this should also be included.

[dgp1130]

Merged to 8.3.x, fix should be included in the new release.

[DanWahlin]

I'm seeing this as a warning message in the Chrome DevTools console with a 9.1.0 production build. Looks like it's generated by my main bundle. I don't see it during the CLI build process (thanks for suppressing that message) - only at runtime in the browser. Is that expected at this point?

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