[PATCH 13/30] Don't call clear_quit_flag in prepare_to_throw_exception

Pedro Alves
2016-03-18T19:25:04Z

I think this is reminiscent of the time when a longjmp would always
jump to the top level. Nowaways code that throw exceptions other than
a quit, which may even be caught and handled without reaching the top
level. Certainly such exceptions shouldn't clear an interrupt
request...

(We also need to get rid of prepare_to_throw_exception in order to be
able to just do "throw ex;" in C++.)

One could argue that we should clear the quit flag when we throw a
quit from the SIGINT handler, when immediate_quit is in effect, to
handle a race, here:

immediate_quit++;
QUIT;

... that's the usual pattern code must use when enabling
immediate_quit. The QUIT is there to catch the case of Ctrl-C having
already been pressed before immediate_quit was enabled. However, this
can happen:

immediate_quit++;
<< Ctrl-C pressed here too.
QUIT;

And in that case, if the quit flag was already set, it'll stay set
even after throwing a quit from the SIGINT handler. The end result is
a double quit. But OTOH, the user did press Ctrl-C two times. Since
I'm getting rid of immediate_quit, I'm not bothering with this.

gdb/ChangeLog:
yyyy-mm-dd Pedro Alves <palves@redhat.com>

* exceptions.c (prepare_to_throw_exception): Don't clear the quit
flag.
---
gdb/exceptions.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/gdb/exceptions.c b/gdb/exceptions.c
index 8ba86fc..b457838 100644
--- a/gdb/exceptions.c
+++ b/gdb/exceptions.c
@@ -30,7 +30,6 @@
void
prepare_to_throw_exception (void)
{
- clear_quit_flag ();
immediate_quit = 0;
}

--
2.5.0