GSXML.m: In function ‘-[GSXMLNode description]’:
GSXML.m:983:38: error: dereferencing pointer to incomplete type
string = UTF8StrLen(buf->buffer->content, buf->buffer->use);
^
GSXML.m:983:60: error: dereferencing pointer to incomplete type
string = UTF8StrLen(buf->buffer->content, buf->buffer->use);
^
gmake[4]: *** [obj/Additions.obj/GSXML.m.o] Error 1
Thanks for making a bug report (we need people to take the time to do that), but when doing so, you really need to report bugs in the current version (svn trunk or at least the latest release).
You are reporting a bug on CentOS-7 (which was only released last year) using a version of GNUstep released three years ago ... so it's not surprising that you have a problem.