Bug#819954: vim-gtk3: crashes on startup under Wayland: gdk_window_get_display: assertion 'GDK_IS_WINDOW (window)' failed

[Simon McVittie]

Package: vim-gtk3
Version: 2:7.4.1689-2
Severity: normal

I'm using GNOME Shell 3.20 in Wayland mode. GNOME 3.20 upstream still
defaults to X11, but GNOME 3.20 in Debian experimental defaults to Wayland
to get more testing on that mode, because GNOME upstream would like to
switch the default in 3.22 and the Debian GNOME maintainers intend to
ship 3.22 in stretch.

Steps to reproduce:

* be in a Wayland session
* vim.gtk3 -g -u NONE -U NONE -N

Expected result: vim with a Gtk3 GUI

Actual result:

> (gvim:31556): Gdk-CRITICAL **: gdk_window_get_display: assertion 'GDK_IS_WINDOW (window)' failed
> Vim: Caught deadly signal SEGV
> Vim: Finished.
> E852: The child process failed to start the GUI
> Press ENTER or type command to continue

and a TUI vim session.

Workaround:

* GDK_BACKEND=x11 vim.gtk3 -g

Suggested fix:

vim appears to assume that Gtk implies X11, so until/unless that assumption
can be disentangled, it should force the use of the X11 backend by putting

    gdk_set_allowed_backends ("x11");

before the first call to gdk_display_open(), gtk_init() or gtk_init_*().

-- Package-specific info:

--- real paths of main Vim binaries ---
/usr/bin/vi is /usr/bin/vim.gtk
/usr/bin/vim is /usr/bin/vim.gtk3
/usr/bin/gvim is /usr/bin/vim.gtk3

-- System Information:
Debian Release: stretch/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.5.0-trunk-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.utf8, LC_CTYPE=en_GB.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages vim-gtk3 depends on:
ii  libacl1              2.2.52-3
ii  libc6                2.22-5
ii  libcairo2            1.14.6-1
ii  libgdk-pixbuf2.0-0   2.32.3-1.2
ii  libglib2.0-0         2.48.0-1
ii  libgpm2              1.20.4-6.1+b2
ii  libgtk-3-0           3.20.1-2
ii  libice6              2:1.0.9-1+b1
ii  liblua5.2-0          5.2.4-1
ii  libpango-1.0-0       1.38.1-1
ii  libpangocairo-1.0-0  1.38.1-1
ii  libperl5.22          5.22.1-9
ii  libpython2.7         2.7.11-7
ii  libruby2.3           2.3.0-5
ii  libselinux1          2.4-3+b1
ii  libsm6               2:1.2.2-1+b1
ii  libtcl8.6            8.6.5+dfsg-2
ii  libtinfo5            6.0+20160319-1
ii  libx11-6             2:1.6.3-1
ii  libxt6               1:1.1.5-1
ii  vim-common           2:7.4.1689-2
ii  vim-gui-common       2:7.4.1689-2
ii  vim-runtime          2:7.4.1689-2

vim-gtk3 recommends no packages.

Versions of packages vim-gtk3 suggests:
pn  cscope            <none>
ii  fonts-dejavu      2.35-1
ii  gnome-icon-theme  3.12.0-1
pn  vim-doc           <none>

-- no debconf information