Re: Change in GCC 5.1.0

[jan.de.kruyf@gmail.com]

On Sunday, April 26, 2015 at 6:51:54 PM UTC+2, Simon Wright wrote:
> GCC 4.9.1 (and presumably GNAT GPL 2014) allowed variable indexing on a
> Set, even though there was no Variable_Indexing aspect in the spec.
> 
> GCC 5.1.0 doesn't.
> 
> So this code (from Gprbuild GPL 2014) compiled and, presumably, worked
> when it shouldn't have:
> 
>    with Ada.Containers.Ordered_Sets;
>    procedure Iteration is
>       type Slave is new Integer;
>       package Slave_S is new Ada.Containers.Ordered_Sets
>         (Element_Type => Slave);
>       Pool : Slave_S.Set;
>       procedure Iterate (Proc : access procedure (S : in out Slave)) is
>       begin
>          for C in Pool.Iterate loop
>             declare
>                S : Slave := Slave_S.Element (C);
>             begin
>                Proc (S);
>                Pool (C) := S;     -- <<<<<<<<<<<<<<< wrong
>             end;
>          end loop;
>       end Iterate;
>    begin
>       null;
>    end Iteration;
> 
> The thing about an (ordered) set is that replacing an element must
> involve re-ordering the set, in case the element's position has
> changed. So the compilable code in this case is
> 
>                Pool.Replace_Element (C, S);
> 
> That said, that looks awfully like tampering to me (if the order
> changes, anyway). I await Gprbuild GPL 2015 with interest.



Hi Simon,
Just to dampen your expectations a bit:
-------------------
$ gcc --version
gcc (GCC) 4.7.4 20140401 for GNAT GPL gpl-2014 (20140405)
Copyright (C) 2012 Free Software Foundation, Inc.
-------------------

And I had Ada code braking before, that should never have passed the compiler in the first place (shame on me).

On another note: I promised to do a write up on my embedded runtime development.. Well the runtime is going ok, but the laptop with my notes on it was nicked, so I went through the moves of rebuilding my development system etc, the last couple of weeks. The work itself was safe though.
And by the way there is still a fair bit of 32 bit stuff in the present Gnat release for Linux.

So as soon as I see that the board is running ok, i.e. the runtime is reasonably tested, I will try to do a summary.


Cheers,

j.