Analyse following RPM build log snippet. Describe contents accurately, without speculation or suggestions for resolution.            
Your analysis must be as concise as possible, while keeping relevant information intact.
Snippet: 

/usr/include/glib-2.0/glib/gmacros.h:1338:43: error: redefinition of âglib_autoptr_cleanup_GtkStackPageâ
 1338 | #define _GLIB_AUTOPTR_FUNC_NAME(TypeName) glib_autoptr_cleanup_##TypeNa
Information about an attempt to redefine a previously defined variable.