On gcc-10 -fno-common is the default which forbids miltiple definitions.
--- a/libgdome/xpath/gdome-xpath-xpnsresolv.h
+++ b/libgdome/xpath/gdome-xpath-xpnsresolv.h
@@ -42,6 +42,6 @@ void gdome_xpath_xpnsresolv_ref (GdomeXPathNSResolver *self, GdomeException *exc
 void gdome_xpath_xpnsresolv_unref (GdomeXPathNSResolver *self, GdomeException *exc);
 GdomeDOMString * gdome_xpath_xpnsresolv_lookupNamespaceURI( GdomeXPathNSResolver *self, GdomeDOMString *prefix, GdomeException *exc);
 
-const GdomeXPathNSResolverVtab gdome_xpath_xpnsresolv_vtab;
+extern const GdomeXPathNSResolverVtab gdome_xpath_xpnsresolv_vtab;
 
 #endif /* GDOME_XPNSRESOLV_FILE */