Where would you start debugging?

Where would you start debugging?

[Peter Brooks]

I've written a small package, there's not much point in putting it here. The moment I run it it is giving me this error:

raised CONSTRAINT_ERROR : erroneous memory access

I'm using gnat on a Mac. The odd thing is that this happens when the calling program simply has a 'with' statement mentioning the package, there's no need to call it.

So, it's clearly part of the iniitalisation of the package.

Where should I start debugging?

I'm doing some conversions from strings to enumerated types, so I've a few lines like this:

"
PACKAGE item_package IS
    NEW Ada.Text_IO.Enumeration_IO( Enum => item_category );
"

So that I can to the conversion later with:

"
item_package.Get(From => String_Split.Slice(subs,1),Item => item.category(item_number),Last => last);
"

This strikes me as the most likely place for it to be going wrong - the compiler is obviously happy, but, at run time, that 'NEW' is falling over with a problem with memory allocation.

Is that likely? If it is, should I forget this method and just parse the string manually?

Re: Where would you start debugging?

[Peter Brooks]

It's OK - I've found the problem. It was opening the same file in two places and that gave the error.

Not immediately obvious...

Re: Where would you start debugging?

[G.B.]

On 27.06.13 15:53, Peter Brooks wrote:
> I've written a small package, there's not much point in putting it here. The moment I run it it is giving me this error:
>
> raised CONSTRAINT_ERROR : erroneous memory access
>
> I'm using gnat on a Mac. The odd thing is that this happens when the calling program simply has a 'with' statement mentioning the package, there's no need to call it.
>
> So, it's clearly part of the iniitalisation of the package.
>
> Where should I start debugging?

If the with-ed package is yours, -gnatVa, -gnatwa, -fstack-check,
and -gnato could help as they add more checks and warnings.
-gnatE and -gnata might also help.

In case the with-ed package is from the run-time system or similar,
I'd add GNAT switches -x, -a, and possibly -m to the above.

Before starting gdb, I'd try a tool like valgrind (of which XCode
has an equivalent IIRC.)

>  should I forget this method and just parse the string manually?

Will 'Value do?

    type Enum is (Yeah, Bee, See);

    ...

    declare
       use Ada.Command_Line;
       Test : Enum;
    begin
       Test := Enum'Value (Argument (1));
       Text_IO.Put_Line (Natural'Image (Enum'Pos (Test)));
    exception
       when Constraint_Error =>
          -- ...
    end;

Re: Where would you start debugging?

[Peter Brooks]

G.B. <rm-dash-bau-haus@dash.futureapps.de> wrote:
> Will 'Value do?
> 
>    type Enum is (Yeah, Bee, See);
> 
>    ...
> 
>    declare
>       use Ada.Command_Line;
>       Test : Enum;
>    begin
>       Test := Enum'Value (Argument (1));
>       Text_IO.Put_Line (Natural'Image (Enum'Pos (Test)));
>    exception
>       when Constraint_Error =>
>          -- ...
>    end;
> 
Perfect - thank you!