Re: [RFC/RFA] gdb.cp/classes.exp: Don't try to print local variable out of scope

[Andrew Cagney <cagney@gnu.org>]

>>>> >BTW, my proposed replacement is woefully inaccurate, which I should
>>>> >have realized before posting.  I do not have a good solution to this
>>>> >problem without actually turning back time :)
>>
>>> 
>>> I'm wondering what the 3.4 wierdness MichaelC's refering to is.
> 
> 
> I dunno.  But the problem here appears to be that there is a lexical
> block which ends before the epilogue, containing the local variables.
> Unlike the inner scope blocks, this one ends before they are destroyed.
> Maybe that's a bug after all.

GDB can't tell the difference - for a variable that has gone out of 
scope, gdb can't tell if it has or hasn't been destroyed -- it has to 
trust GCC.

However [to play sick mind games] there's nothing in the rule book 
saying that GDB/GCC need to follow the language rules.  It should be 
possible for GCC to manipulate things such that a variable remains 
visible until its location has been reused.

> Now consider this example:
>> 
> 
>>>>> >>> 10 0x10 <stuff>: ret		stuff(int) { }
>>>>> >>> 11 0x20 <main>: push		main() {
>>>>> >>> 12 0x21 <main+1>: push			{
>>>>> >>> 13 0x22 <main+2>: move arg1, i			stuff(i)
>>>>> >>> 14 0x23 <main+3>: call stuff			  "
>>>>> >>> 15                  			}
>>>>> >>> 16 0x25 <main+5>: pop  2; ret	}


Andrew