winpty aliases applied unnecessarily in Windows Terminal; break env var cygpath rewriting

[cspotcode]

Existing issues matching what you're seeing

• I was not able to find an open or closed issue matching what I'm seeing

Git for Windows version

git version 2.52.0.windows.1

Windows version

Windows 11

Windows CPU architecture

x86_64 (64-bit)

Additional Windows version information

Microsoft Windows [Version 10.0.26100.7171]
(c) Microsoft Corporation. All rights reserved.

Options set during installation

Editor Option: VisualStudioCode
Custom Editor Path: 
Default Branch Option: main
Path Option: Cmd
SSH Option: OpenSSH
Tortoise Option: false
CURL Option: WinSSL
CRLF Option: LFOnly
Bash Terminal Option: ConHost
Git Pull Behavior Option: FFOnly
Use Credential Manager: Enabled
Performance Tweaks FSCache: Enabled
Enable Symlinks: Enabled
Enable FSMonitor: Disabled

Other interesting things

No response

Terminal/shell

Git Bash

Commands that trigger the issue

# Run from "Git Bash" in a "Windows Terminal" window. Also works in VSCode's integrated terminal
# We get the winpty alias outside of mintty
$ command -v node
alias node='winpty node.exe'

# This happens because $TERM is set:
$ echo $TERM
xterm-256color

# We still have a functional TTY even *without* the alias. This means the alias is unnecessary outside of mintty, right?
$ node.exe -p process.stdout.isTTY # Bypass the alias.
true

# Problem: winpty breaks common scripting scenarios, such as piping
$ node -p process.versions | grep v8
stdout is not a tty

# It *should* work like this:
$ node.exe -p process.versions | grep v8
  v8: '9.6.180.15-node.15',

# Problem: winpty breaks env var path conversions
$ ( WORKDIR='/c/Users/me/projects/libfoo' node -p '({TEMP: process.env.TEMP, WORKDIR: process.env.WORKDIR})' )
{
  TEMP: 'C:\\Users\\me\\AppData\\Local\\Temp',
  WORKDIR: '/c/Users/me/projects/libfoo'
}

# Expected WORKDIR to be converted like below: (bypassing alias with exec)
$ ( WORKDIR='/c/Users/me/projects/libfoo' exec node -p '({TEMP: process.env.TEMP, WORKDIR: process.env.WORKDIR})' )
{
  TEMP: 'C:\\Users\\me\\AppData\\Local\\Temp',
  WORKDIR: 'C:/Users/me/projects/libfoo'
}

Expected behaviour

When invoking node, winget, etc from Git Bash in Windows Terminal:

• env vars and positional arguments are treated the same as with all other commands
• piping, output capture, and other shell-isms work as expected

The above should be true because:

• winpty bash aliases are not declared outside of mintty

Can this be accomplished by checking something other than $TERM? Check TERM_PROGRAM="mintty", check exit code of tty -s?

Actual behaviour

node, winget, etc are aliased as winpty node, winpty winget, etc.

Env vars are not converted consistently compared to other, non-aliased commands.

Repository

No response

[cspotcode]

In short, I'm asking if git-for-windows/build-extra#78 can be amended, and aliases.sh can implement a more robust check for mintty and the necessity of winpty.

Hitting stdout is not a tty is one thing. But silently deciding to convert env vars differently is the kind of subtle bug that can eat up a bunch of time until you figure out what is going on.

Is $TERM_PROGRAM a reliable variable to check for mintty?

[cspotcode]

Linking to adjacent tickets for my future reference:

• Path conversion with and without winpty differs msys2/MSYS2-packages#411
• mintty issues #74
• Bug: Cannot kill Nodejs process using ctrl + c #1219
• Winpty doesn't appear to work with devenv #899
• [winpty] output is not a tty #519
• (Some) interactive commands unusable with git-bash.exe #399
• node stdout is not a tty #2651
• git-extra: add aliases to support interactive consoles in mintty build-extra#78

---

• Yarn throws "stdout is not a tty" in Git Bash yarnpkg/yarn#2591

[cspotcode]

To see all the differences:

$ winpty node.exe -p process.env
$ node.exe -p process.env
# Diff the results.  Can't use `diff <() <()` because winpty requires a TTY

[dscho]

I'm asking if git-for-windows/build-extra#78 can be amended, and aliases.sh can implement a more robust check for mintty and the necessity of winpty.

If you find such a more robust check, feel free to open a PR, and I'll work with you on getting it merged.

[cspotcode]

@dscho thank you, I created a PR here: git-for-windows/build-extra#664