Graphics.wait_next_event in Win32 hangs if window closed.

[vicuna]

Original bug ID: 3963
Reporter: anonymous
Status: closed (set by @damiendoligez on 2013-06-03T19:00:27Z)
Resolution: fixed
Priority: normal
Severity: major
Version: 3.09.0
Target version: 4.01.0+dev
Fixed in version: 4.01.0+dev
Category: ~DO NOT USE (was: OCaml general)
Monitored by: @Chris00

Bug description

Call Graphics.open_graph "" to open the graphics window.
Call Graphics.wait_next_event.
Close the window by clicking on the close box with the mouse.

wait_next_event will never return, and the caller has no
way of knowing that the window has gone away.

I looked through the source code in ocaml-3.09.1/otherlibs/win32graph.
In open.c/GraphicsWndProc(), when a WM_DESTROY message arrives, the
message is passed to caml_gr_handle_event() as usual. But
caml_gr_handle_event() is not sensitive to a WM_DESTROY message.
So the waiting call from Graphics.wait_next_event continues
to wait forever.

[vicuna]

Comment author: @damiendoligez

Since Graphics.wait_next_event does not have a return value for this case, I've fixed this by making it raise Graphic_failure as it does under X-window, although the message is not the same.

Fixed in trunk/4.01 (rev 13740).