mintty.exe is a strange terminal

[gabyx]

It would be really nice if somebody could look at the following issue:
golang/go#46681

It demonstrates the fact that git-bash.exe and also mingw.exe really behave strange, when we want to the get the controlling terminal file input CONIN$ on windows.

This is basically done in GO with:

package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"syscall"

	"golang.org/x/term"
)

func GetCttyIn() (io.Reader, error) {
	in, err := syscall.Open("CONIN$", syscall.O_RDWR, 0)
	if err != nil {
		return nil, err
	}

	fmt.Println("$CONIN Isterm: ", isatty.IsTerminal(uintptr(in)))

	return os.NewFile(uintptr(in), "/dev/tty"), nil
}

func main() {

	fmt.Println("In: ", term.IsTerminal(int(os.Stdin.Fd())))
	fmt.Println("Out: ", term.IsTerminal(int(os.Stdout.Fd())))

	in, err := GetCttyIn()
	if err != nil {
		panic(err)
	}
	scanner := bufio.NewScanner(in)

	success := scanner.Scan()
	if !success {
		panic(err)
	}
	fmt.Println("Res:", scanner.Text())
}

Running the above with echo "asd" | go run main.go
in vs code integrate terminal with bash.exe (MSYS2) **works **(suprisingly) but

running it in the git-bash.exe or msyswin64.exe (mintty.exe) does not work:

VS Code: (bash.exe)

In:  false
Out:  true
$CONIN Isterm:  true
asd
Res: asd

Correct!

Straight mintty.exe

In:  false      
Out:  false  // <<<< Thats wrong!
$CONIN Isterm:  true
                 //  <<<<--- STUCK at READ here!

[Biswa96]

Technically speaking, there is something common between git-for-windows and msys2.

[jeremyd2019]

winpty? conpty? Basically mintty uses "cygwin" ptys, not native Windows consoles, so trying to interact with the attached native Windows console from within it is usually doomed to failure. winpty is a program that tries to work around this, and conpty is a new thing that should help, but is still buggy so not enabled by default here (or in git bash).

[jeremyd2019]

Personally, I don't use mintty because of this. I either run within the native console host, or now in Windows Terminal.

[Biswa96]

@gabyx Can you provide equivalent code in C?

[julie777]

I suspect it is the same problem that I have which causes python to report that stdout is not a tty.
Add ConPTY=on to your minttyrc file.