Starting and terminating erl.exe under powershell "corrupts" it

[josevalim]

Describe the bug

Create this file, called proc.ps1:

$output = Start-Process -FilePath "erl.exe" -NoNewWindow -Wait -PassThru
exit $output.ExitCode

Now invoke proc.ps1 inside Powershell on Windows and it should start the Erlang shell. However, if you press Ctrl+C, it quits Erlang but leaves the shell in a weird state where Ctrl+C and similar do not work anymore.

Affected versions

I can reproduce it on 27.2. I am honestly not sure if this is an Erlang bug or not, maybe it is PowerShell doing weird things, but since I got a minimal reproduction I thought I would report it upstream. It was originally reported here: elixir-lang/elixir#14174

[frazze-jobb]

I was able to replicate this on Windows 10, and with a different behavior on Windows 11. We are handling Ctrl+C correctly by returning TRUE in the interrupt handler. But PowerShell "StartProcess -NoNewWindow -Wait" mode seems to also get the Ctrl+C signal, which causes it to print the prompt and somehow hijack the input. If I type slowly, inputted characters are mostly read by Powershell. If I type fast then some characters are read by erl.exe. If I type "exit" slowly I can exit the PowerShell session and continue with the erl.exe session.

On Windows 11, If I type Ctrl+C then the PowerShell session prints its prompt and then exits. So the erl.exe session is still in a usable state.

I reported a bug on PowerShell through feedback hub on windows.

[max-au]

Leaving it here if anyone stumbles over this and just needs a temporary fix:

(Blindly) typing stty sane and pressing Enter will recover powershell terminal to be usable again.