Failed to open /dev/tty with vscode debugger

In my program, I tried to read /dev/tty. The program cannot open the file with vscode debugger, but the file is successfully opened with gdb command line.

The source code is:

#include <stdio.h>
#include <fcntl.h>

int main(int argc, char const *argv[])
{
    int f = open("/dev/tty", O_RDONLY);
    printf("open tty %d\n",f);
    return 0;
}

The program is then build with g++ -g ./main.cpp.

When I use gdb to debug in vscode, it gives:

open tty -1

However, with command line gdb ./a.out, the file can be open successfully.

(gdb) r
Starting program: /home/miki0w0/c_test/a.out
open tty 3
[Inferior 1 (process 22818) exited normally]
(gdb) q

A same open issue can be found at https://stackoverflow.com/questions/52027368/unable-to-open-dev-ttyusb0-while-debugging-with-visual-studio-code-on-linux.

The vscode debugger works well in other cases. I wounder what causes the difference and how to fix it.

The environment is:

• OS and Version: Ubuntu 16.04
• VS Code Version: 1.32.3
• C/C++ Extension Version: 0.22.1
• Other extensions you installed (and if the issue persists after disabling them): None

Additional context
My configure file is:
launch.json.txt.

And the log information is included in this file:
debuglog.txt

Start by comparing the attached launch.json and debuglog.txt with the command-line gdb invocation, then inspect how the VS Code C++ debugger launches the program and provides its controlling terminal. Reproduce the issue on the stated Ubuntu 16.04 setup with the sample /dev/tty program; done means the VS Code debug run opens /dev/tty as the command-line run does.