Bug 1106276

Summary:

mpz_invert returns incorrect value

Product:

[Fedora] Fedora

Reporter:

Dennis Gilmore <dennis>

Component:

gmp

Assignee:

Frantisek Kluknavsky <fkluknav>

Status:

CLOSED UPSTREAM

QA Contact:

Fedora Extras Quality Assurance <extras-qa>

Severity:

unspecified

Docs Contact:

Priority:

unspecified

Version:

rawhide

CC:

efintzel, fkluknav, loganjerry, normand, paulo.cesar.pereira.de.andrade, tomspur

Target Milestone:

---

Target Release:

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Hardware:

Unspecified

OS:

Unspecified

Whiteboard:

Fixed In Version:

Doc Type:

Bug Fix

Doc Text:

Story Points:

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Clone Of:

Environment:

Last Closed:

2014-11-06 18:06:35 UTC

Type:

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Regression:

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Mount Type:

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Documentation:

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CRM:

Verified Versions:

Category:

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oVirt Team:

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RHEL 7.3 requirements from Atomic Host:

Cloudforms Team:

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Target Upstream Version:

Embargoed:

Bug Depends On:

Bug Blocks:

1051573, 1105908

Attachments:

Description	Flags
build.log	none
root.log	none
state.log	none

Description Dennis Gilmore 2014-06-09 04:07:53 UTC

Your package flint failed to build from source in current rawhide.

http://koji.fedoraproject.org/koji/taskinfo?taskID=6964188

For details on mass rebuild see https://fedoraproject.org/wiki/Fedora_21_Mass_Rebuild

Comment 1 Dennis Gilmore 2014-06-09 04:08:08 UTC

Created attachment 904388 [details]
build.log

Comment 2 Dennis Gilmore 2014-06-09 04:08:10 UTC

Created attachment 904389 [details]
root.log

Comment 3 Dennis Gilmore 2014-06-09 04:08:11 UTC

Created attachment 904390 [details]
state.log

Comment 4 Jerry James 2014-06-09 19:22:15 UTC

This is a test failure due to a change in the GMP function mpz_invert.  Consider the following code:

#include <gmp.h>
#include <stdio.h>
#include <stdlib.h>

int
main ()
{
  mpz_t d, e, f;

  mpz_inits(d, e, f, NULL);
  mpz_set_ui(d, 100);
  mpz_set_si(e, -1);
  if (mpz_invert(f, d, e))
    gmp_printf("Inverse is %Zd\n", f);
  else
    puts("Inverse does not exist");
  mpz_clears(d, e, f, NULL);
  return EXIT_SUCCESS;
}

On Fedora 20 (gmp 5.1.2), this prints:
Inverse does not exist

On Rawhide (gmp 6.0.0), this prints:
Inverse is 0

Comment 5 Jerry James 2014-06-09 19:32:49 UTC

This is a bug in GMP.  Try replacing the -1 with various other values in:

  mpz_set_si(e, -1)

and you will quickly see that mpz_invert() is returning zero when it should be returning nonzero, and is returning nonzero when it should be returning zero.

Comment 6 Michel Normand 2014-07-22 08:09:06 UTC

as per http://ppc.koji.fedoraproject.org/koji/taskinfo?taskID=1959124
the flint-2.4.2-4.fc21  do build at least on ppc64 et ppc64le.

Comment 7 Frantisek Kluknavsky 2014-11-06 18:06:35 UTC

It is a deliberate upstream decision to have "anything modulo +-1 = 0", as discussed in https://gmplib.org/list-archives/gmp-bugs/2014-April/003440.html and following posts. Documentation shipped in the source tarball does not yet reflect this change but is already fixed in upstream git repo https://gmplib.org/repo/gmp/diff/55ff6b8d9a92/doc/gmp.texi .

Except +1 and -1, I could not find any other modulus with weird behaviour.