Gdb support for exceptions (Re: using backtrace() in exception throwing?)

[Jan Holesovsky]

Hi Tom,

Tom Tromey píše v Pá 22. 02. 2013 v 11:14 -0700:

> Michael> Even better than this would (perhaps) be a "break inside thrower that
> Michael> is caught here" type breakpoint - that we could invoke to land us in
> Michael> whatever code is going to throw as it does that [ and before it started
> Michael> all the magic cleanup / unwinding work ]. That is - assuming that it's
> Michael> possible for the code to know (at that point) where it will ultimately
> Michael> end up (? ;-)
> 
> I think it isn't possible in general.  When an exception is thrown, I
> think all that can really be determined is the next catch point.
> 
> What this means is that if you have a series of throws and re-throws,
> winding up at some "catch", then the best you could do is stop at the
> re-throw that leads to that catch.

Even if this is not solving everything / the general case, I think this
would still be pretty useful for LibreOffice - I don't remember being
bitten by rethrows when debugging LO problems.  And always one could set
this thing [how to call it, actually? ;-)] where the re-throw happens,
and try again - still it would save quite some time compared to first
setting a breakpoint to get to the relevant piece of code + catch throw
+ catch catch + hope that they are the right ones.

> Here, suppose the comment marks the catch you are concerned with.
> You want to find the throw that leads to this point.
> 
> The original throw in "doit" can only see as far as the catchpoint in
> "dd2".  That is because arbitrary code can be run there -- for example
> it may swallow the exception and no more throwing is even done.
> 
> So this hypothetical breakpoint would only trigger at the re-throw in
> dd2.

In other words - I'd love if gdb were able to do this even with the
re-throw limitation :-)

All the best,
Kendy