[pypy-dev] int_py_mod_nonnegargs(): one arg is negative LLAssertFailure

[Armin Rigo]

Hi,

On 9 December 2016 at 02:00, Shubha Ramani via pypy-dev
<pypy-dev at python.org> wrote:
> Why am I getting this error ?
> pidigits.py runs fine outside of the pytest environment.

I'm getting:

    from rpython.jit.metainterp.test.support import LLJitMixin,X86JitMixin
E   ImportError: cannot import name X86JitMixin

After hacking at that until the test runs (replacing it with
LLJitMixin), then I see the problem.  It's likely caused by integer
overflow.  Your f() function computes the digits of pi, but it's not
valid RPython because integers overflow the size of C 'long'.  An
internal test then fails because although '(n*3 + a) % d' was
supposedly proven to occur on known-nonnegative arguments, the value
did overflow and is now negative.  Copying the same algorithm in C
with the type 'long' everywhere would be similarly undefined C code.


Armin