Re: Extra information in the message string of exceptions.

[Jerry <list_email@icloud.com>]

On Monday, June 6, 2022 at 1:49:08 PM UTC-7, DrPi wrote:
> Le 06/06/2022 à 14:59, Rod Kay a écrit : 
> > Hi all, 
> > 
> >    Any thoughts on pro's/con's of having the Ada standard packages 
> > runtime provide extra information in the message string of exceptions ? 
> > 
> >    For instance, a Constraint_Error message might provide details on 
> > the variable name, the legal range and the erroneous value which caused 
> > the exception. 
> >
> +1 
> 
> > 
> > Regards.

This is not responsive to the OP but here is a bit of code that I find extremely useful to get a symbolic traceback for unhandled exceptions. Here is an example:

with Common; use Common;
with Ada.Exceptions;

procedure CE_2 is
    i : Positive;
    j : Integer := 1;    

    procedure A_Subroutine is
    begin
        i := -j;
    end A_Subroutine;

begin
    A_Subroutine;

    -- Print a traceback for all unhandled exceptions.
    -- See http://www.adacore.com/adaanswers/gems/gem-142-exceptions/.
    exception
    when Error : others =>
        Common.Print_Traceback_For_Unhandled_Exception(Error);
end CE_2;

It provides this output:

==========================================================
Exception name: CONSTRAINT_ERROR
Message: ce_2.adb:10 range check failed
Load address: 0x100000000
Call stack traceback locations:
0x1000013ac 0x1000013cd 0x100001c36
    <<<<<< Symbolic Traceback >>>>>>
    If incomplete, compile with -O0.
ce_2__a_subroutine.3035 (in run) (ce_2.adb:10)
_ada_ce_2 (in run) (ce_2.adb:14)
main (in run) (b__ce_2.adb:354)
==========================================================

I can post the code that does this if anyone is interested. The gist is calling Ada.Exceptions.Exception_Information, massaging that information, and calling atos. (Is atos macOS-specific?)

Jerry