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Is Single step into C++ virtual thunk still broken?
- From: Daedalus <daedalus at projecticarus dot com>
- To: gdb at sources dot redhat dot com
- Date: 08 Jul 2002 14:42:17 +0100
- Subject: Is Single step into C++ virtual thunk still broken?
I have waded through the archives but can't find anything newer than 1
year ago discussing this.
I'm using latest cvs gdb and gcc3.1. and specifiying DWARF-2 debug info.
When I single step into a virtual member function of a polymorphic
object in my C++ app, the source display heads off to some random line
in a header file, and another single step takes me back to the next
source line after the virtual function.
Putting a breakpoint in the actual function being called works as
expected.
I quote from a message by Andrew Cagney, 28 Jun 2001:
*****************************
> - Skipping vtable thunks, if necessary
I don't know if this was ever discussed on this list. As I understand
it, v3 virtual function is sometimes called via a ``thunk''. A
``thunk'' pulls a rabbit out of a hat (finds the correct object to pass
to the real function) and then passes control to the real function.
At present, if GDB stepped into a thunk it would find no line info,
treat it like a library and just skip it - oops, step into virtual
functions via thunks doesn't work.
One proposed solution is to mimic / generalize the shared library
mechanism so that GDB will single step through it to the real function.
I think this bug is pretty serious since, GDB will, randomly loose
control over the target. I certainly think it is more serious than the
constructor problem.
*****************************
Is this still broke, or am I missing something?
Andrew Walrond
Project Icarus