Mix: warn when project app name matches a dependency

[pckrishnadas88]

Summary

This PR adds a warning in Mix.Project when a project’s application name is the same as one of its dependencies.

Details

Currently, if a project declares an app name that is identical to one of its dependencies, Elixir doesn’t warn the user. This can lead to unexpected behaviors, such as hanging compilers when trying to start tasks from the dependency.

This fix implements warn_on_duplicate_app_name/1 in mix/project.ex that prints a warning using Mix.shell().error/1. The associated test Mix.ProjectTest verifies the behavior.

Example

If a user creates a project with:

mix new aoc

and adds {:aoc, "~> 0.16.0"} to deps, running:

mix deps.get
mix aoc.set

will print:

warning: the application name :aoc is the same as one of its dependencies

Related Issue

Fixes: [elixir-lang/elixir#14972](#14972)

[josevalim]

Hi @pckrishnadas88, thank you for the PR! Although I would likely move the check elsewhere, perhaps on Mix.Dep.Loader or somewhere else where we already traverse the dependencies...

[pckrishnadas88]

Hi @josevalim,

Thanks for the feedback! I’ve moved the check to Mix.Dep.Loader and added a test that verifies the warning prints when the project app name matches a dependency. Verified locally with a temporary project.

I’m still learning Elixir, so any guidance or feedback is greatly appreciated.

PTAL!

—Krishnadas

[josevalim]

Please move it inside the with_scm_and_app, so we don't have to traverse deps twice!

[pckrishnadas88]

Thanks for the feedback!

I’ve moved the duplicate app name warning into with_scm_and_app. Please let me know if anything else is needed.

[josevalim]

Why this change? 🤔

[pckrishnadas88]

Thanks for the question — I might be missing something here.

I added the locked? check because when I remove it, the following test starts failing:

test raises when no SCM is specified (Mix.DepTest)
     test/mix/dep_test.exs:115
     Expected exception Mix.Error but got MatchError (no match of right hand side value:

         {:error, {:hex, {~c"no such file or directory", ~c"hex.app"}}}
     )
     code: with_deps(deps, fn ->
     stacktrace:
       lib/hex.ex:5: Hex.start/0
       (mix 1.20.0-dev) lib/mix/hex.ex:64: Mix.Hex.start/0
       (mix 1.20.0-dev) lib/mix/dep/loader.ex:193: Mix.Dep.Loader.with_scm_and_app/5
       (mix 1.20.0-dev) lib/mix/dep/loader.ex:145: Mix.Dep.Loader.to_dep/4
       (elixir 1.20.0-dev) lib/enum.ex:1717: Enum."-map/2-lists^map/1-1-"/2
       (mix 1.20.0-dev) lib/mix/dep/loader.ex:376: Mix.Dep.Loader.mix_children/3
       (mix 1.20.0-dev) lib/mix/dep/loader.ex:22: Mix.Dep.Loader.children/1
       (mix 1.20.0-dev) lib/mix/dep/converger.ex:101: Mix.Dep.Converger.all/4
       (mix 1.20.0-dev) lib/mix/dep/converger.ex:93: Mix.Dep.Converger.converge/4
       (mix 1.20.0-dev) lib/mix/dep/converger.ex:76: Mix.Dep.Converger.converge/1
       (elixir 1.20.0-dev) lib/file.ex:2013: File.cd!/2
       test/test_helper.exs:174: MixTest.Case.in_fixture/3
       test/mix/dep_test.exs:35: Mix.DepTest.with_deps/2
       test/mix/dep_test.exs:118: (test)

I’m not fully sure what the intended behavior is here, so I added the guard to keep the existing test behavior.
Happy to change this if there’s a better approach.

[josevalim]

Take a look at test/mix/tasks/deps_test.exs and see how tests with dependencies are handled. We already have some dependencies that we can handle, such as ok and git_repo, and you can create a project with the same name as one of those deps. You can then also move the test to test/mix/tasks/deps_test.exs :)

[pckrishnadas88]

Thanks! I’ve moved the test to test/mix/tasks/deps_test.exs and reused the existing :ok dependency fixture as suggested. All make test_mix passes locally.

[josevalim]

💚 💙 💜 💛 ❤️

[pckrishnadas88]

Thank you! 💚💙💜💛❤️