perl build errors on Fedora

[Ben Pfaff]

I recently switched from Debian to Fedora on my development machine,
and I'm hitting a bunch of errors building the Perl module.  I suspect that
it's a Perl version difference. Fedora 33 has Perl 5.32.1.

For now, I'll build without Perl.

Here are the error messages:

In file included from /usr/lib64/perl5/CORE/perl.h:5606,
                from PSPP.xs:28:
PSPP.xs: In function ‘value_to_scalar’:
PSPP.xs:160:27: error: pointer targets in passing argument 2 of
‘Perl_newSVpvn’ di
ffer in signedness [-Werror=pointer-sign]
 160 |       return newSVpvn (val->s, width);
     |                        ~~~^~~
     |                           |
     |                           uint8_t * const {aka unsigned char * const}
/usr/lib64/perl5/CORE/embed.h:383:44: note: in definition of macro ‘newSVpvn’
 383 | #define newSVpvn(a,b)  Perl_newSVpvn(aTHX_ a,b)
     |                                            ^
In file included from /usr/lib64/perl5/CORE/perl.h:5567,
                from PSPP.xs:28:
/usr/lib64/perl5/CORE/proto.h:2433:57: note: expected ‘const char *
const’ but arg
ument is of type ‘uint8_t * const’ {aka ‘unsigned char * const’}
2433 | PERL_CALLCONV SV* Perl_newSVpvn(pTHX_ const char *const buffer,
const STRL
EN len)
     |                                       ~~~~~~~~~~~~~~~~~~^~~~~~
PSPP.c: In function ‘XS_PSPP_onBoot’:
PSPP.c:357:15: error: unused variable ‘ver’ [-Werror=unused-variable]
 357 |  const char * ver = (const char *)SvPV_nolen(ST(0))
     |               ^~~
In file included from PSPP.xs:29:
PSPP.c: In function ‘XS_PSPP__Var_set_missing_values’:
/usr/lib64/perl5/CORE/XSUB.h:177:28: error: unused variable ‘targ’
[-Werror=unused
-variable]
 177 | #define dXSTARG SV * const targ = ((PL_op->op_private &
OPpENTERSUB_HASTAR
G) \
     |                            ^~~~
/usr/lib64/perl5/CORE/XSUB.h:177:28: note: in definition of macro ‘dXSTARG’
 177 | #define dXSTARG SV * const targ = ((PL_op->op_private &
OPpENTERSUB_HASTAR
G) \
     |                            ^~~~
PSPP.c:868:6: error: unused variable ‘RETVAL’ [-Werror=unused-variable]
 868 |  int RETVAL;
     |      ^~~~~~
PSPP.c:866:7: error: unused variable ‘v1’ [-Werror=unused-variable]
 866 |  SV * v1 = ST(1)
     |       ^~
In file included from /usr/lib64/perl5/CORE/perl.h:3912,
                from PSPP.xs:28:
PSPP.xs: In function ‘XS_PSPP__Var_add_value_label’:
/usr/lib64/perl5/CORE/sv.h:1762:18: error: pointer targets in passing
argument 3 o
f ‘value_copy_str_rpad’ differ in signedness [-Werror=pointer-sign]
1761 |     (SvPOK_nog(sv) \
     |     ~~~~~~~~~~~~~~~~
1762 |      ? SvPVX(sv) : sv_2pv_flags(sv, 0, SV_GMAGIC))
     |      ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     |                  |
     |                  char *
PSPP.xs:519:43: note: in expansion of macro ‘SvPV_nolen’
 519 |   value_copy_str_rpad (&the_value, width, SvPV_nolen(key), ' ');
     |                                           ^~~~~~~~~~
In file included from /home/blp/pspp/master/src/data/caseproto.h:25,
                from /home/blp/pspp/master/src/data/case.h:26,
                from /home/blp/pspp/master/src/data/dictionary.h:22,
                from PSPP.xs:40:
/home/blp/pspp/master/src/data/value.h:46:57: note: expected ‘const
uint8_t *’ {ak
a ‘const unsigned char *’} but argument is of type ‘char *’
  46 | void value_copy_str_rpad (union value *, int dst_width, const uint8_t *,
     |                                                         ^~~~~~~~~~~~~~~
In file included from PSPP.xs:29:
/usr/lib64/perl5/CORE/XSUB.h:177:28: error: unused variable ‘targ’
[-Werror=unused
-variable]
 177 | #define dXSTARG SV * const targ = ((PL_op->op_private &
OPpENTERSUB_HASTAR
G) \
     |                            ^~~~
/usr/lib64/perl5/CORE/XSUB.h:177:28: note: in definition of macro ‘dXSTARG’
 177 | #define dXSTARG SV * const targ = ((PL_op->op_private &
OPpENTERSUB_HASTAR
G) \
     |                            ^~~~
PSPP.c:1181:6: error: unused variable ‘RETVAL’ [-Werror=unused-variable]
1181 |  int RETVAL;
     |      ^~~~~~