Re: C++ to Ada95 -- bitten!

[Laurent Guerby <guerby@acm.org>]

"Nick J Chackowsky" <nick@arcticmail.com> writes:
> Ahaaaa... the _compiler_ attempted to "solve" the poorly formed exponent and
> crashed in the attempt?

That's likely to be the explanation. Note that the compiler is
required by the standard to be exact for static numerical computations.

The following code should print 1.0 on all Ada 95 compilers
(and the constant will be generated at compile time, look at
the assembly generated using the -S GCC switch).

with Ada.Text_IO; use Ada.Text_IO;

procedure PT is
   X : constant := 1.0 + 2.0 ** (-1000);
   Y : constant := 1.0 + 2.0 ** (-1001);
   Z : constant := 2.0 ** (1001) * (X - Y);
begin
   Put_Line (Float'Image (Z));
end PT;


> I too would have expected a compile error rather than a compiler crash. I
> will submit a bug report.

Reasonable. Note that you should mention what compiler you are using
together with its version and the OS (wether you're submitting a bug
or posting here for help ;-).

-- 
Laurent Guerby <guerby@acm.org>