When building Evolution on Solaris 9 with Forte, happened error as follows: 

/opt/SUNWspro/bin/cc -DHAVE_CONFIG_H -I. -I. -I../../.. -I.. -I./..
-I./../../.. -I../../../intl -I../../../camel -I../../../e-util
-D_REENTRANT -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include
-I/usr/include/gtk-2.0 -I/usr/include/libxml2 -I/usr/include/libglade-2.0
-I/usr/lib/gtk-2.0/include -I/usr/include/atk-1.0 -I/usr/include/pango-1.0
-I/usr/openwin/include -I/usr/include/libart-2.0
-I/usr/local/include/gal-2.0 -I/usr/local/include/libgnomeprint-2.2
-I/usr/local/nspr-4.2.2/include -I/usr/local/nss-3.7.1/include
-DG_LOG_DOMAIN=\"camel-pop3-provider\" -DG_DISABLE_DEPRECATED
-I/usr/include -I/usr/local/include -g -I/usr/include -I/usr/local/include
-g -Wp,-MD,.deps/camel-pop3-store.pp -c camel-pop3-store.c  -KPIC -DPIC -o
camel-pop3-store.o
"../../../camel/camel-folder-summary.h", line 71: warning: integer overflow
detected: op "<<"
"camel-pop3-store.c", line 407: warning: argument #1 is incompatible with
prototype:
        prototype: pointer to const char : "/usr/include/iso/string_iso.h",
line 72
        argument : pointer to unsigned char
"camel-pop3-store.c", line 409: warning: argument #1 is incompatible with
prototype:
        prototype: pointer to const char : "/usr/include/iso/string_iso.h",
line 72
        argument : pointer to unsigned char
"camel-pop3-store.c", line 417: warning: argument #1 is incompatible with
prototype:
        prototype: pointer to const char : "/usr/include/iso/string_iso.h",
line 72
        argument : pointer to unsigned char
"camel-pop3-store.c", line 419: warning: argument #2 is incompatible with
prototype:
        prototype: pointer to const char : "../../../camel/camel-sasl.h",
line 64
        argument : pointer to unsigned char
"camel-pop3-store.c", line 419: warning: assignment type mismatch:
        pointer to unsigned char "=" pointer to char
"camel-pop3-store.c", line 529: operands have incompatible types:
         pointer to unsigned char ":" pointer to char
"camel-pop3-store.c", line 595: cannot recover from previous errors
cc: acomp failed for camel-pop3-store.c
make[4]: *** [camel-pop3-store.lo] Error 1
make[4]: Leaving directory
`/export/home/work/work/evolution/camel/providers/pop3'

fixing:
camel-pop3-store.c, line 529
-        store->engine->line ? store->engine->line: _("Unknown error"));
+        store->engine->line );

passed