Thread overview
ieeeFlags do not work properly
Jan 07, 2010
Torben Hagerup
Jan 07, 2010
Don
January 07, 2010
Run under D version 2.037, the program below runs through without raising any assert exceptions. This shows an erratic behavior with respect to ieeeFlags that is hardly intended. Other ieeeFlags also work (or, rather, do not work) in unexpected ways.

--------------------

import std.math;

void main() {
// The execution leads to no assert errors
 real a,b=3.5;
 resetIeeeFlags();
 assert(!ieeeFlags.divByZero); // so far no zero division
 a=3.5/0.0L; // but now ...
 assert(a==real.infinity); // yes, exactly
 assert(!ieeeFlags.divByZero); // perhaps not, after all
 b/=0.0L; // once more, the same, really
 assert(b==real.infinity); // yes, the same
 assert(ieeeFlags.divByZero); // oops, not the same after all?
}

January 07, 2010
Torben Hagerup wrote:
> Run under D version 2.037, the program below runs through without raising any assert exceptions. This shows an erratic behavior with respect to ieeeFlags that is hardly intended. Other ieeeFlags also work (or, rather, do not work) in unexpected ways.
> 
> --------------------
> 
> import std.math;
> 
> void main() {
> // The execution leads to no assert errors
>  real a,b=3.5;
>  resetIeeeFlags();
>  assert(!ieeeFlags.divByZero); // so far no zero division
>  a=3.5/0.0L; // but now ...
>  assert(a==real.infinity); // yes, exactly
>  assert(!ieeeFlags.divByZero); // perhaps not, after all
>  b/=0.0L; // once more, the same, really
>  assert(b==real.infinity); // yes, the same
>  assert(ieeeFlags.divByZero); // oops, not the same after all?
> }

Hi!

Please report bugs in Bugzilla:

  http://d.puremagic.com/issues/index.cgi

This newsgroup is just a feed from Bugzilla.

-Lars
January 07, 2010
Torben Hagerup wrote:
> Run under D version 2.037, the program below runs through without raising any assert exceptions. This shows an erratic behavior with respect to ieeeFlags that is hardly intended. Other ieeeFlags also work (or, rather, do not work) in unexpected ways.
> 
> --------------------

This isn't a bug.

> import std.math;
> 
> void main() {
> // The execution leads to no assert errors
>  real a,b=3.5;
>  resetIeeeFlags();
>  assert(!ieeeFlags.divByZero); // so far no zero division
>  a=3.5/0.0L; // but now ...

This occurred at compile time. At runtime, this became:
a = real.infinity;

>  assert(a==real.infinity); // yes, exactly
>  assert(!ieeeFlags.divByZero); // perhaps not, after all
>  b/=0.0L; // once more, the same, really

It's not the same. This is a runtime division by zero.

>  assert(b==real.infinity); // yes, the same
>  assert(ieeeFlags.divByZero); // oops, not the same after all?
> }