rbx-2.0.0pre pg gem compile error

gistfile1.txt

Fetching: pg-0.11.0.gem (100%)
Building native extensions.  This could take a while...
ERROR:  Error installing pg:
	ERROR: Failed to build gem native extension.

        /Users/julien/.rvm/rubies/rbx-2.0.0pre/bin/rbx extconf.rb
checking for pg_config... yes
Using config values from /usr/local/bin/pg_config
checking for libpq-fe.h... yes
checking for libpq/libpq-fs.h... yes
checking for PQconnectdb() in -lpq... yes
checking for PQconnectionUsedPassword()... yes
checking for PQisthreadsafe()... yes
checking for PQprepare()... yes
checking for PQexecParams()... yes
checking for PQescapeString()... yes
checking for PQescapeStringConn()... yes
checking for PQgetCancel()... yes
checking for lo_create()... yes
checking for pg_encoding_to_char()... yes
checking for PQsetClientEncoding()... yes
checking for struct pgNotify.extra in libpq-fe.h... yes
checking for unistd.h... yes
creating extconf.h
creating Makefile

make
gcc -I. -I. -I/Users/julien/.rvm/rubies/rbx-2.0.0pre/include -I. -DRUBY_EXTCONF_H=\"extconf.h\"  -I/usr/local/Cellar/postgresql/9.0.0/include -fPIC -ggdb3 -O2 -fPIC  -c compat.c
gcc -I. -I. -I/Users/julien/.rvm/rubies/rbx-2.0.0pre/include -I. -DRUBY_EXTCONF_H=\"extconf.h\"  -I/usr/local/Cellar/postgresql/9.0.0/include -fPIC -ggdb3 -O2 -fPIC  -c pg.c
pg.c:69: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
pg.c:70: error: expected ‘)’ before ‘*’ token
pg.c: In function ‘new_pgresult’:
pg.c:117: error: ‘rb_encoding’ undeclared (first use in this function)
pg.c:117: error: (Each undeclared identifier is reported only once
pg.c:117: error: for each function it appears in.)
pg.c:117: error: ‘enc’ undeclared (first use in this function)
pg.c: In function ‘pgconn_init’:
pg.c:305: error: ‘rb_encoding’ undeclared (first use in this function)
pg.c:305: error: ‘enc’ undeclared (first use in this function)
pg.c:328: warning: assignment makes pointer from integer without a cast
pg.c: In function ‘pgconn_s_escape’:
pg.c:1310: error: ‘rb_encoding’ undeclared (first use in this function)
pg.c:1310: error: ‘enc’ undeclared (first use in this function)
pg.c: In function ‘enc_get_index’:
pg.c:3740: error: ‘ENCODING_INLINE_MAX’ undeclared (first use in this function)
pg.c: At top level:
pg.c:3748: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
pg.c:3772: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
pg.c:3814: error: expected ‘)’ before ‘*’ token
pg.c: In function ‘pgconn_internal_encoding_set’:
pg.c:3876: warning: assignment makes pointer from integer without a cast
pg.c:3883: error: ‘rb_eEncCompatError’ undeclared (first use in this function)
pg.c: In function ‘init_m17n’:
pg.c:3960: warning: assignment makes pointer from integer without a cast
make: *** [pg.o] Error 1