[pkg-boost-devel] Bug#844495: boost: multiprecision acos() sometimes does not return (also Bug#844490: FTBFS with boost1.62)

[Thibaut Paumard]

Dear all,

I was able to construct a minimal example, just needed to find a
specific value to trigger the bug:

8<--------------8<------------8<

#include <boost/multiprecision/cpp_dec_float.hpp>

int main(int argc, char** argv) {

  boost::multiprecision::cpp_dec_float_100 alpha100, a, b;
  alpha100=5.9839860068377014046259e-02;
  b=cos(alpha100);
  a=acos(b);

  return 0;
}

8<--------------8<------------8<

I compiled that on s390x (sid chroot on zelenka) with g++ (Debian
6.2.1-4) 6.2.1 20161119 and the resulting binary never returns.

The same on jessie (Boost 1.55.0+dfsg-3, g++ (Debian 4.9.2-10) 4.9.2)
runs through.

In addition:

Le 21/11/2016 à 10:02, Thibaut Paumard a écrit :
>   - this indicates that even more architectures are affected. amd64
> and i386 seem not to be. The complete list of architectures on which I
> have been able to trigger the problem is: arm64 armel armhf mips64el
> ppc64el s390x powerpc ppc64.

mipsel too.

However the specific values that trigger the bug may be different on the
various architectures and seem to depend on the number of digits.

Regards, Thibaut.