GCC 10 and higher treat enums differently and the way that cpio(1)/pax(1) use
them is no longer supported.  This is similar, but not identical, to the patch
used by Gentoo for sys-apps/heirloom-tools.

This should be upstreamable, but sadly, there is no upstream any more.
--- heirloom-pax-1.0/cpio/cpio.c.old	2024-05-25 11:20:07.088299291 -0500
+++ heirloom-pax-1.0/cpio/cpio.c	2024-05-25 11:25:21.674430528 -0500
@@ -824,6 +824,9 @@
 static int		compressed_bar;	/* this is a compressed bar archive */
 static int		formatforced;	/* -k -i -Hfmt forces a format */
 static long long	lineno;		/* input line number */
+enum fmttype		fmttype;	/* type of archive format */
+enum pax		pax;		/* type of pax command this is */
+enum pax_preserve	pax_preserve;	/* attributes to preserve */
 
 int			pax_dflag;	/* directory matches only itself */
 int			pax_kflag;	/* do not overwrite files */
--- heirloom-pax-1.0/cpio/cpio.h.old	2007-03-26 13:14:57.000000000 -0500
+++ heirloom-pax-1.0/cpio/cpio.h	2024-05-25 11:23:54.143854185 -0500
@@ -31,7 +31,7 @@
 #include <sys/stat.h>
 #include <inttypes.h>
 
-enum	{
+enum fmttype	{
 	FMT_NONE	= 00000000,	/* no format chosen yet */
 
 	TYP_PAX		= 00000010,	/* uses pax-like extended headers */
@@ -70,7 +70,8 @@
 	FMT_BAR		= 00400001,	/* bar format type */
 
 	FMT_ZIP		= 01000000	/* zip format */
-} fmttype;
+};
+extern enum fmttype	fmttype;
 
 /*
  * Zip compression method.
@@ -173,11 +174,12 @@
 extern char		*progname;
 extern struct glist	*patterns;
 
-enum {			/* type of pax command this is */
+enum pax {			/* type of pax command this is */
 	PAX_TYPE_CPIO		= 0,	/* not a pax command */
 	PAX_TYPE_PAX1992	= 1,	/* POSIX.2 pax command */
 	PAX_TYPE_PAX2001	= 2	/* POSIX.1-2001 pax command */
-} pax;
+};
+extern enum pax		pax;
 extern int		pax_dflag;
 extern int		pax_kflag;
 extern int		pax_nflag;
@@ -185,14 +187,15 @@
 extern int		pax_uflag;
 extern int		pax_Xflag;
 
-enum {
+enum pax_preserve {
 	PAX_P_NONE	= 0000,
 	PAX_P_ATIME	= 0001,
 	PAX_P_MTIME	= 0004,
 	PAX_P_OWNER	= 0010,
 	PAX_P_MODE	= 0020,
 	PAX_P_EVERY	= 0400
-} pax_preserve;
+};
+extern enum pax_preserve	pax_preserve;
 
 extern size_t		(*ofiles)(char **, size_t *);
 extern void		(*prtime)(time_t);