Re: [RFA 3/5] Use std::string, std::vector in rust-lang.c

[Pedro Alves <palves@redhat.com>]

On 09/22/2016 08:35 PM, Pierre Muller wrote:

>   Just out of curiosity:
> how are such variables treated by gcc regarding debug information?
> 
>   What is the scope of definition of those variables?
> And is it correctly handled by current GDB?

On my system, they look like as if declared at the top of
the scope.  Up until they're initialized, they'll have garbage
contents, and that's what gdb will show.  But that's no different from
actually declaring a variable at the top of the scope and only
initializing it after.  It's not a big deal.

There's a GNU extension that I think is meant to make it possible
for the debugger to treat uninitialized variables
specially (DW_OP_GNU_uninit), though I don't think we do
much with it.  Not sure gcc emits it, even.

> 
>   IIRC (but my knowledge about C++ if far
> worse than for plain C.. which itself I only learned to be able to
> contribute to GDB...) the reason why we can remove the cleanups is
> that the compiler will insert auto--magically
> the destructors of those local variables at the end of
> their respective scope, is this correct? 

Correct.

>  
>> So I think there's no ground for objection.
> 
>   Not that I want to raise an objection,
> I just wonder if debugging GDB by itself will remain as easy as it was!

Hope so too...

Thanks,
Pedro Alves