GNAT does not consistently raise an exception to log(0.0)

[Jerry <lanceboyle@qwest.net>]

When the following program is built with any of theses compilers:

GNATMAKE GPL 2013 (20130314) (downloaded from AdaCore)
GNATMAKE GPL 2011 (20110419) (downloaded from AdaCore)
GNATMAKE 4.8.0 (Simon Wright's build)

like this:

$ gnatmake -f bomb_log.adb -OX

then if X = 0 (zero) the expected exception is raised and reported thusly:

raised CONSTRAINT_ERROR : a-ngelfu.adb:744 explicit raise

else if X > 0 no exception is raised.


with Ada.Numerics.Long_Elementary_Functions; 
use  Ada.Numerics.Long_Elementary_Functions;
procedure Bomb_Log is
    x : Long_Float;
begin
    x := log(0.0);
end Bomb_Log;


However, under the same conditions as above, the following program raises the exception always:


with Ada.Numerics.Long_Elementary_Functions; 
use  Ada.Numerics.Long_Elementary_Functions;
with Ada.Text_IO;
use  Ada.Text_IO;
procedure Bomb_Log is
    x : Long_Float;
begin
    x := log(0.0);
    Put_Line(Long_Float'Image(x));
end Bomb_Log;


Jerry

P.S. What is the meaning of -O99999 as a gnatmake argument?