Mix.cmd sometimes crashes with error in encoding on Windows 11

[clemensm]

Elixir and Erlang/OTP versions

Erlang/OTP 25 [erts-13.0.4] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1]

Elixir 1.17.3 (compiled with Erlang/OTP 25)

Operating system

windows 11 home

Current behavior

Hi all

We've got a Phoenix project where in the mix assets.deploy phase we copy a couple of files in the windows build using basically this line:

"cmd robocopy a b /MIR"

This is working fine when being executed manually (i.e. we've got a build.bat script), i.e. logged into the machine, running a cmd session, running the bat file. However if we execute this via Jenkins, where the same computer that we've used manually is running as a Jenkins slave, this will fail with an error:

** (ArgumentError) argument error
(stdlib 5.2.3.2) io.erl:103: :io.put_chars(:standard_io, <<32, 32, 32, 82, 79, 66, 79, 67, 79, 80, 89, 32, 32, 32, 32, 32, 58, 58, 32, 32, 32, 32, 32, 82, 111, 98, 117, 115, 116, 101, 115, 32, 68, 97, 116, 101, 105, 107, 111, 112, 105, 101, 114, 101, 110, 32, 102, 129, 114, 32, ...>>)
(elixir 1.17.3) lib/system.ex:1145: System.do_port_byte/3
(elixir 1.17.3) lib/system.ex:1131: System.do_cmd/3
(mix 1.17.3) lib/mix/shell.ex:132: Mix.Shell.cmd/3
(mix 1.17.3) lib/mix/tasks/cmd.ex:72: Mix.Tasks.Cmd.run/1
(mix 1.17.3) lib/mix/task.ex:495: anonymous fn/3 in Mix.Task.run_task/5
(mix 1.17.3) lib/mix/task.ex:561: Mix.Task.run_alias/6
(mix 1.17.3) lib/mix/cli.ex:96: Mix.CLI.run_task/2

After trying around a bit I stumbled upon this, which has the same error when compiling argon2_elixir (which was happening with us as well, but an update of elixir_make solved the issue):

#13637

Trying out that fix suggested by @josevalim by modifying the line mix.exs solved this problem:

"cmd cscp 65001 & robocopy a b /MIR"

So I assume that in mix there is a very similar line somewhere?

Sadly it's hard to reproduce, since you need to setup a Jenkins master server, and a Jenkins slave as well to trigger this, so I hope this information is enough to find the issue...

Happy to help if you need more info!

Expected behavior

The line should be executed without an error

[josevalim]

I sent a PR here: #14027

Can you please verify if it works? Perhaps the simplest way to do so is by:

1. Write the contents of this file to disk: https://raw.githubusercontent.com/elixir-lang/elixir/ad5fbcfb45d0d41d75fb825cc01ee0dc97fdae43/lib/mix/lib/mix/shell/io.ex

2. Run elixirc path/to/file.ex

3. It will output a Elixir.Mix.Shell.IO.beam, which you can now copy to the lib/mix/ebin directory of your installation (it should replace a file)

And then run the command again and let me know if it works?