Re: ping: [gcc patch] libcc1: '@' GDB array operator

["Manuel López-Ibáñez" <lopezibanez@gmail.com>]

On 03/06/15 18:30, Jeff Law wrote:
>> It's common to have something like the struct hack where the length of
>> the array is stored in the struct.  Then when scripting gdb one can
>> write:
>>
>>      print s.array[0] @ s.length
> Which is case that I've had use for a non-constant  RHS as well.  I just
> haven't had to use it all that much.

To implement that case, you still do not need the compiler to parse @, you just 
need the compiler to parse s.array[0] and s.length independently. It should be 
possible to arrange the inferior code in such a way that GCC parses each side 
of @ independently and gives the info necessary to GDB such that it can 
interpret what @ means or give a reasonable error.

I discussed this at length here: https://gcc.gnu.org/ml/gcc/2015-03/msg00187.html

At https://gcc.gnu.org/ml/gcc/2015-03/msg00183.html I propose other 
alternatives, which in principle are more work to implement, but move GCC in 
the direction of being able to parse snippets of code. In my opinion this is 
moving backwards: making GCC less flexible and adding very special cases that 
are likely to conflict with other things.

Parsing correctly arbitrary programs that may contain @ at arbitrary places 
seems a can full of gigantic were-worms.

Cheers,

Manuel.