When we build libgnomeprintui (one of evolution's dependent pkg) evolution
on Solaris using Forte, we met this info:

/opt/SUNWspro/bin/cc -DHAVE_CONFIG_H -I. -I. -I../.. -I../.. -I../../intl
-I../../libgnomeprintui -DWE_ARE_LIBGNOMEPRINT_INTERNALS
-I/usr/local/include/libgnomeprint-2.2 -I/usr/local/include/libart-2.0
-I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include
-I/usr/local/include/libxml2 -I/usr/local/include/pango-1.0
-I/usr/include/libgnomecanvas-2.0 -I/usr/include/pango-1.0
-I/usr/sfw/include -I/usr/sfw/include/freetype2 -I/usr/include/gtk-2.0
-I/usr/lib/gtk-2.0/include -I/usr/include/atk-1.0 -DG_DISABLE_DEPRECATED
-DGDK_DISABLE_DEPRECATED -DGTK_DISABLE_DEPRECATED
-DGDK_PIXBUF_DISABLE_DEPRECATED -DGNOME_DISABLE_DEPRECATED
-DGNOMELOCALEDIR=\"/usr/local/share/locale\" -DBINDIR=\"/usr/local/bin\"
-DDATADIR=\"/usr/local/share\" -I/usr/include -I/usr/openwin/share/include/
-g -c gpa-widget.c  -KPIC -DPIC -o gpa-widget.o
"gpa-widget.c", line 42: identifier redeclared: gpa_widget_get_type
        current : function(void) returning unsigned long
        previous: function(void) returning unsigned int : "./gpa-widget.h",
line 59
"gpa-widget.c", line 92: warning: statement not reached
cc: acomp failed for gpa-widget.c
make[3]: *** [gpa-widget.lo] Error 1
make[3]: Leaving directory
`/evolution/libgnomeprintui-2.2.1/libgnomeprintui/gpaui'

How often does this happen? 

Always.

Additional Information:

A fix to this one may be:
Changed the line in ~/libgnomeprintui-2.2.1/libgnomeprintui/GtkType
gpa_widget_get_type(void);gpaui/gpa-widget.h 
"GtkType gpa_widget_get_type(void);"
to
"GType gpa_widget_get_type(void);"

Please give a discussion and then we will add a patch.