Re: [PATCH][gdb/testsuite] Fix gdb.python/py-finish-breakpoint2.exp with -m32

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2021-01-21 3:45 a.m., Tom de Vries wrote:
> On 1/21/21 9:29 AM, Tom de Vries wrote:
>> The different outcomes for -m32 and -m64 are both valid given the
>> semantics of FinishBreakpoint, which is "set at the return address of a
>> frame".  It all depends where that return address is.  There is no
>> guarantee that the return address is an insn that uniquely represent the
>> function return control path.
> 
> And, reading the documentation:
> ...
> Function: FinishBreakpoint.out_of_scope (self)
> 
>     In some circumstances (e.g. longjmp, C++ exceptions, GDB return
>     command, …), a function may not properly terminate, and thus never
>     hit the finish breakpoint. When GDB notices such a situation, the
>     out_of_scope callback will be triggered.
> ...
> this may be somewhat misleading or unclear, given that it's possible (as
> the -m64 case demonstrates) that both:
> - the function does properly terminate, and
> - the finish breakpoint still hits (meaning the stop method is called).
> 
> Thanks,
> - Tom
> 

I think don't see how FinishBreakpoint can be useful with that kind of
inconsistency.  Given that an exception is thrown in both cases, and the
throw_exception_1 call frame never properly terminates, it seems obvious
to me that out_of_scope should be called both times, and stop should not
be called, both times.

Simon