Can't read stdout of bash with GSubprocess on MSYS2

[Gang Chen <gang chen cn gmail com>]

Hi,
I'm writing a GTK+ application with MINGW-W64, which spawns a subprocess running bash to execute some commands with GSubprocess and reads stdout of bash (installed from MSYS2). I found that if compiled without "-mwindows" compilation option the main process can read the stdout, while with "-mwindows", the read function always returns 0 bytes read. If the main process runs a normal console program, or like "mingw32/bin/gcc.exe", then it can read stdout even if compiled with "-mwindows".
The code:

#include <glib.h>
#include <gio/gio.h>
#include <gtk/gtk.h>
#include <stdio.h>

char buffer[100];
GtkTextView *text;

void ondataread(GObject *s, GAsyncResult *r, gpointer p)
{
    GError *error = NULL;
    int l = g_input_stream_read_finish(G_INPUT_STREAM(s), r, &error);
    if (error)
        printf("read error: %s\n", error->message);
    else if (l > 0)
    {
        gtk_text_buffer_insert_at_cursor(gtk_text_view_get_buffer(text), buffer, l);
        g_input_stream_read_async(G_INPUT_STREAM(s), buffer, 100, G_PRIORITY_DEFAULT, NULL, ondataread, NULL);
    }
}

int main(int argc, char **argv)
{
    char *subpargv[8] = { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL };
    subpargv[0] = "D:\\msys64\\usr\\bin\\bash.exe";
    subpargv[1] = "-c";
    subpargv[2] = "echo good; sleep 10; pwd";
//    subpargv[0] = "C:\\Windows\\system32\\cmd.exe";
//    subpargv[1] = "/c";
//    subpargv[2] = "echo good";
//    subpargv[0] = "D:\\msys64\\mingw32\\bin\\gcc.exe";
//    subpargv[1] = "notfile";
    GSubprocessLauncher *l = g_subprocess_launcher_new(G_SUBPROCESS_FLAGS_STDOUT_PIPE | G_SUBPROCESS_FLAGS_STDERR_PIPE);
    GError *error = NULL;
    GSubprocess *p = g_subprocess_launcher_spawnv(l, subpargv, &error);
    if (!p)
    {
        printf("spawn error: %s\n", error->message);
        return -1;
    }
    g_object_unref(l);
    g_input_stream_read_async(g_subprocess_get_stdout_pipe(p), buffer, 100, G_PRIORITY_DEFAULT, NULL, ondataread, NULL);
    g_input_stream_read_async(g_subprocess_get_stderr_pipe(p), buffer, 100, G_PRIORITY_DEFAULT, NULL, ondataread, NULL);
    gtk_init(&argc, &argv);
    GtkWidget *win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    GtkWidget *t = gtk_text_view_new();
    gtk_container_add(GTK_CONTAINER(win), t);
    text = GTK_TEXT_VIEW(t);
    gtk_widget_show_all(win);
    gtk_main();
    return 0;
}

How to read stdout correctly?
Thanks,
Gang