While building pango 0.30.1 (latest stable), the open Build Service aborts the build due to detected implicit declarations.

From the build log:
***
  CC     querymodules.o
querymodules.c: In function 'main':
querymodules.c:245:2: warning: implicit declaration of function 'pango_config_key_get_system' [-Wimplicit-function-declaration]
querymodules.c:245:7: warning: assignment makes pointer from integer without a cast [enabled by default]
  CCLD   libpango-1.0.la
****

pango_config_key_get_system is being referenced (using grep) in:
pango/pango-utils.c: * pango_config_key_get_system:
pango/pango-utils.c:pango_config_key_get_system (const char *key)
pango/querymodules.c:   path = pango_config_key_get_system ("Pango/ModulesPath");
pango/pango.def:        pango_config_key_get_system

pango-utils.c has a declaration of this function, but querymodules.c does not have any prototype information, thus resulting in the warning / error.

This patch solves the issue on my builds:
Index: pango-1.30.1/pango/pango-utils.h
===================================================================
--- pango-1.30.1.orig/pango/pango-utils.h
+++ pango-1.30.1/pango/pango-utils.h
@@ -48,6 +48,8 @@ void     pango_lookup_aliases (const cha
                               int          *n_families);
 #endif /* PANGO_ENABLE_BACKEND */

+char *   pango_config_key_get_system (const char *key);
+
 gboolean pango_parse_enum     (GType       type,
                               const char *str,
                               int        *value,