Assignment of small Float values

[David W. Glessner <david_glessner@my-deja.com>]

Why does GNAT treat the non-zero constant as 0.0 in the assignment to
F1 in the following example?  32-bit IEEE floating-point should
support values down to around 10**-38 (and even down to 10**-45 or
so for subnormal numbers).

Note that Rational Apex Ada behaves as I expected.

Is there something in Ada that allows the assignment of 0.0 or is
this a GNAT bug?


-- Test program that shows unexplained (to me at least) GNAT behavior
for
-- floating point assignments.
--
-- GNAT 3.12p Win98 displays:
-- 0.00000E+00                           <-- Why does GNAT display 0.0?
-- 6.66666666666667E-33
-- 6.66667E-33
--
-- Rational Apex 3.0.0b for Solaris (Sparc) displays:
-- 6.66667E-33
-- 6.66666666666667E-33
-- 6.66667E-33
with Ada.Text_Io;
procedure Test_Float_Range is
    C : constant := 6.6666666666666666E-33;
    F1 : Float := C;
    F2 : Long_Float := C;
    F3 : Float := Float (F2);
    use Ada.Text_Io;
begin
    Put_Line (Float'Image (F1));
    Put_Line (Long_Float'Image (F2));
    Put_Line (Float'Image (F3));
end Test_Float_Range;


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