Re: gdb.Value returning a string of length 1 (linux lx-version bug)

Hi Kieran,

On 2016-03-22 18:54, Kieran Bingham wrote:
> Hi Jan,
> 
> Me and Pete have just been looking into the gdb.Value object bug where
> the lx-version command  returns a string of length 1.
> 
> As I recall at FOSDEM, you were also hitting the bug.
> Out of interest, what compiler version are you using?

gcc (SUSE Linux) 4.8.3 20140627 [gcc-4_8-branch revision 212064]

> 
> We've made some head way, but we are suspicious that compiler versions
> may affect the issue ! :(
> 
> The crux of the issue, is that the valpy_string() calls c_get_string()
> which in turn calls get_discrete_bounds().
> 
> On my broken version, get_discrete_bounds, is setting both lowp, and
> highp to 0x0; where as on Peters working version, his highp gets set
> correctly. (there is a +1 added later which results in the string
> producing a strlen of 1)
> 
> I'm running gcc 5.2.1-22ubuntu2, whereas Pete is running gcc 4.8.4.
> 
> Pete's version of his compiled binutils-gdb always seems to function
> correctly, where as I hit the bug - *occasionally*
> 
> Of course, since I have compiled with -g3 -O0 -fsanitize=undefined I
> can't reproduce the issue, and now even removing the optimise levels I
> haven't been able to reproduce.
> 
> We have a Heisenbug :(

Maybe wait for someone seeing this more reproducibly? :-/

Jan

> 
> Has anyone else on the GDB Mailinglist experienced any intermittent
> errors with gdb.Value strings from python?
> --
> Kieran
> 

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