Re: expression function bug or think?

[Simon Wright <simon@pushface.org>]

Florian Weimer <fw@deneb.enyo.de> writes:

> Out of curiosity, can you show us the expanded Ada code, using -gnatG?

GNAT GPL 2011, with -gnatp:

functions_E : short_integer := 0;

package functions is
   function functions__fib (n : natural) return natural;

   function functions__fib (n : natural) return natural is
   begin
      return
         do
            T2s : natural;
            case n is
               when 0 =>
                  T2s := 0;
               when 1 =>
                  T2s := 1;
               when others =>
                  T2s := functions__fib (n - 1) + functions__fib (n -
                    2);
            end case;
         in T2s end
      ;
   end functions__fib;
end functions;

GNAT GPL 2011, without -gnatp:

functions_E : short_integer := 0;

package functions is
   function functions__fib (n : natural) return natural;

   function functions__fib (n : natural) return natural is
   begin
      return
         do
            T2s : natural;[constraint_error when
              not (n - 1 >= 0)
              "range check failed"][constraint_error when
              not (n - 2 >= 0)
              "range check failed"][constraint_error when
              not (interfaces__unsigned_32!(n) <= 16#7FFF_FFFF#)
              "invalid data"]
            case n is
               when 0 =>
                  T2s := 0;
               when 1 =>
                  T2s := 1;
               when others =>
                  T2s := functions__fib (n - 1) + functions__fib (n -
                    2);
            end case;
         in T2s end
      ;
   end functions__fib;
end functions;



Pretty conclusive, I think!