[Debian-science-sagemath] cypari2 hangs on ppc64el when pari stack overflows

[Tobias Hansen]

Hi,

sagemath 8.3 currently fails to build on ppc64el due to a test that triggers a pari stack overflow sometimes hanging indefinitely. The bug can be triggered by the following Python code:

import cypari2
pari = cypari2.Pari()
pari.allocatemem(200000)
pari('x^2 + 10^100 + 1').nfinit()

The last line sometimes hangs indefinitely on ppc64el instead of throwing an error. When running the equivalent code directly in gp (here one needs a smaller stack size to trigger the overflow)

allocatemem(50000)
p = x^2 + 10^100 + 1
nfinit(p)

it throws the error as on other architectures. So I think the bug should be in cysignals or cypari2. Before reporting this (which will maybe not help much since people usually don't have access to this architecture) it would be good to test with the latest version of cysignals (we still have 1.6.7). What's the status of getting that packaged?

Best,

Tobias