Mix cmd output has wrong encoding on Linux (since #14027)

[mediremi]

Elixir and Erlang/OTP versions

Erlang/OTP 27 [erts-15.2] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [jit:ns]

Elixir 1.18.0 (compiled with Erlang/OTP 27)

Operating system

Linux

Current behavior

Using mix cmd to run programs that print out non-ASCII characters results in incorrectly encoded output. This behaviour is since #14027.

To reproduce, run mix cmd echo ✔. The output will be â instead of ✔.

Expected behavior

This bug is due to Mix.Shell.IO.cmd/2 using IO.binwrite instead of IO.write even on non-Windows systems.

iex(1)> Mix.Shell.cmd("echo ✔", [], &IO.write/1)
✔
0
iex(2)> Mix.Shell.cmd("echo ✔", [], &IO.binwrite/1)
â
0

I think the following change should fix this (if this looks good happy to make a PR):

def cmd(command, opts \\ []) do
  print_app? = Keyword.get(opts, :print_app, true)

  Mix.Shell.cmd(command, opts, fn data ->
    if print_app?, do: print_app()
    case :os.type() do
      {:win32, _} ->
        # Due to encoding of shell command on Windows,
        # let's write the data as is
        IO.binwrite(data)
      
      _ -> IO.write(data)
    end
  end)
end