Re: changing alignment of built-in boolean

[Anonymous Coward <spam@spam.com>]

In article <Nv14f.1603$hY6.1538@newsread1.news.pas.earthlink.net>, Jeffrey R. Carter wrote:
> 
> You might want to look at user-defined boolean types here (it's
> sometimes a little confusing in Ada to distinguish between integer
> types and type Integer, character types and type Character, string
> types and type String, boolean types and type Boolean):
> 
> type Big_Boolean is new Boolean;
> for Big_Boolean'Size use 32;
> for Big_Boolean'Alignment use 4;
> 
> Conditions can be of any boolean type, so you can use this just like
> type Boolean:
> 
> B : Big_Boolean;
> 
> if B then ...
> 
> while B loop ...
> 
> exit Some_Loop when B;

I tried this, and where I had problems was trying to assign the result
of a boolean expression to Big_Boolean.  ie. Compiling:

   procedure Big_Boolean_Experiment is

      type Big_Boolean_Type is new Boolean;

      --The following line is probably useless on booleans:
      pragma Convention (Convention => C,
                         Entity     => Big_Boolean_Type);

      for Big_Boolean_Type'Size use 32;

      Big_Boolean    : Big_Boolean_Type;
      Native_Boolean : Boolean;

   begin

      Big_Boolean    := 2=2; --gnat rejects this line
      Native_Boolean := 2=2;

   end Big_Boolean_Experiment;

results in this error from gnat:

   $ gcc -c -gnatR3 big_boolean_experiment.adb
   big_boolean_experiment.adb:14:23: expected type "Big_Boolean_Type" defined at line 3
   big_boolean_experiment.adb:14:23: found type "Standard.Boolean"

   $ gcc --version
   gcc (GCC) 3.2.2 20030222 (Red Hat Linux 3.2.2-5)