Recursion halted on mix alias using "File.cp_r"

[RaymondLoranger]

Elixir and Erlang/OTP versions

I have a mix.exs that invokes the following docs alias:

  defp aliases do
    [
      docs: ["docs", &copy_images/1]
    ]
  end

  defp copy_images(_) do
    File.cp_r("images", "doc/images",
      on_conflict: fn src, dst ->
        IO.gets(~s|Overwriting "#{dst}" with "#{src}".\nProceed? [Yn]\s|) in [
          "y\n",
          "Y\n"
        ]
      end
    )
  end

When I run mix docs the 8 files in images are copied recursively to doc/images as illustrated in the attached.
However when I run mix cmd elixir --color -S mix docs only the first file is copied and the process freezes.

mix docs.docx

mix.exs.docx

Operating system

Windows 10

Current behavior

When I run mix cmd elixir --color -S mix docs only the first file is copied and the process is frozen.

Expected behavior

When I run mix cmd elixir --color -S mix docs all 8 files should be copied recursively without any freezing.

[josevalim]

Yes, in this case it is intentional. mix cmd does not forward stdin requests to the invoked subcommand, so you cannot interact with the underlying terminal. In this case, I would recommend not relying on mix cmd to invoke Elixir itself. If you really need to shell out with stdin redirection, I recommend using projects like porcelain or erlexec.