unfortunately xv (to which I'm pretty fond too being the image viewer I used a lot when I started with Slackware) has been dropped upstream since some years and, looking around, doesn't seem to be maintained anymore...
to fix this error should be relatively easy, you can patch the SlackBuild like this
Code:
--- ./xv.SlackBuild.orig 2018-04-23 19:20:59.038170130 +0200
+++ ./xv.SlackBuild 2021-07-27 08:46:37.228125000 +0200
@@ -65,6 +65,10 @@
fi
zcat $CWD/C.gz | patch -p1 --verbose --backup --suffix=.orig || exit 1
zcat $CWD/xv-libpng-1.5.patch.gz | patch -p0 --verbose --backup --suffix=.orig || exit 1
+
+# fix for the newer jasper
+sed -i "s|fp\,void\ |fp,const void |" xvjp2k.c
+
make -f Makefile.std || exit 1
strip --strip-unneeded bggen vdcomp xcmap xv xvpictoppm
mkdir -p $PKG/usr/bin
or, in alternative, apply another patch (with -p1) after the others in the SlackBuild
Code:
--- ./xvjp2k.c.orig 2021-07-27 08:55:22.186125000 +0200
+++ ./xvjp2k.c 2021-07-27 08:56:30.079125000 +0200
@@ -76,7 +76,7 @@
*/
int jas_getdbglevel(void) {return 0;}
int jas_setdbglevel(int n) {return 0;}
-int jas_memdump(FILE *fp,void *data,size_t len) {return 0;}
+int jas_memdump(FILE *fp,const void *data,size_t len) {return 0;}
int jas_eprintf(const char *fmt,...) /* Handle JasPer Library message */
{
or integrate the xv.jasper.diff.
but who knows which kind of disruptive changes will be in the future in the libraries xv uses...
