bug#12350: Composites identified as primes in factor.c (when HAVE_GMP)

[Jim Meyering]

Pádraig Brady wrote:
...
>> Thanks, but wouldn't that be a slight "pessimization"?
>> What do you think about providing the missing function instead?
>> Maybe not worth the hassle, but still, it would avoid adding those 12
>> in-function lines.  factor.c is already large and complex enough that
>> every little bit helps.
>
> Borderline, but to align code with newer libs,
> I've done as you suggest in the attached.
...

Thank you!
That looks great.

> Subject: [PATCH] build: support older GMP versions
>
> The new factor code introduced usage of mpz_inits() and
> mpz_clears(), which are only available since GMP >= 5,
> and will result in a compile error when missing.
>
> * m4/gmp.m4 (cu_GMP): Define HAVE_DECL_MPZ_INITS appropriately.
> * src/factor (mpz_inits): New function, defined where missing.
> (mpz_clears): Likewise.
> ---
>  m4/gmp.m4    |    2 ++
>  src/factor.c |   23 +++++++++++++++++++++++
>  2 files changed, 25 insertions(+), 0 deletions(-)
>
> diff --git a/m4/gmp.m4 b/m4/gmp.m4
> index e337e16..59a664f 100644
> --- a/m4/gmp.m4
> +++ b/m4/gmp.m4
> @@ -30,6 +30,8 @@ AC_DEFUN([cu_GMP],
>          LIB_GMP=$ac_cv_search___gmpz_init
>          AC_DEFINE([HAVE_GMP], [1],
>            [Define if you have GNU libgmp (or replacement)])
> +        # This only available in GMP >= 5

           # This is available only in GMP >= 5

> +        AC_CHECK_DECLS([mpz_inits], [], [], [[#include <gmp.h>]])
>         }],
>        [AC_MSG_WARN([libgmp development library was not found or not usable.])
>         AC_MSG_WARN([AC_PACKAGE_NAME will be built without GMP support.])])