Switch-Process, when used to replace the PowerShell process with an interactive (different) shell session, breaks that session

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest released version
• Search the existing issues.
• Refer to the FAQ.
• Refer to Differences between Windows PowerShell 5.1 and PowerShell.

Steps to reproduce

Clearly not a common use case, but a bug nonetheless:

When you use Switch-Process (exec) to replace the current PowerShell process (running an interactive session) with a different shell’s interactive session (e.g., bash), that session’s command-line editing is broken.

# Run on macOS or Linux
Switch-Process /bin/bash

Expected behavior

A regular interactive Bash session.

Actual behavior

What the user types on the Bash command line doesn’t print (however, submitting commands and printing output works normally).

Error details

No response

Environment data

PowerShell Core 7.3.0-rc.1 on macOS 12.6 or Linux

Visuals

No response

[daxian-dbw]

Instead of PowerShell, It could be what .NET does, or more specifically, what [Console]::Readkey does. The following is quoted from the blog about “Console.ReadKey” improvement:

tcsetattr allows for changing the terminal settings. It’s used by .NET to apply its own setting at startup, and restore the previous settings at rundown.

[SteveL-MSFT]

I’m guessing that fish, zsh, etc… is explicitly setting stty to echo whereas older shells do not. Don’t understand what other shells are doing to make it work. Here’s something that’s a bit interesting:

PS> stty
speed 38400 baud;
lflags: echoe echok echoke echoctl pendin
iflags: iutf8
oflags: -oxtabs
cflags: cs8 -parenb
[61.39ms] /Users/steve
PS> pwsh -c { exec stty }
speed 38400 baud;
lflags: echoe echok echoke echoctl pendin
iflags: iutf8
oflags: -oxtabs
cflags: cs8 -parenb
[318.76ms] /Users/steve
PS> pwsh
PowerShell 7.3.0-rc.1
/Users/steve
PS> exec stty
speed 38400 baud;
lflags: -icanon -iexten -echo echoe echok echoke echoctl pendin
iflags: -icrnl -ixon iutf8
oflags: -oxtabs
cflags: cs8 -parenb

So interactive mode for PowerShell is doing something affecting the tty.