Sorry if this is a ruby-core thing but I'm not subscribed there.
(I also have the feeling I reported this once but I can't find it in the 
archives, sorry if I double post it)

Anyway, trying to build the preview release of ruby 1.8.3 on an old 
debian box, I get this two warnings for ext/openssl:

gcc -fPIC -g -O2  -I. -I../.. -I/home/riffraff/ruby-1.8.3 
-I/home/riffraff/ruby-1.8.3/ext/openssl -DHAVE_UNISTD_H 
-DHAVE_SYS_TIME_H -DHAVE_ASSERT_H -DHAVE_OPENSSL_SSL_H 
-DHAVE_OPENSSL_CONF_API_H -DHAVE_BN_PSEUDO_RAND_RANGE 
-DHAVE_BN_RAND_RANGE -DHAVE_VA_ARGS_MACRO  -c ossl_cipher.c
ossl_cipher.c: In function `ossl_cipher_pkcs5_keyivgen':
ossl_cipher.c:208: warning: passing arg 2 of `EVP_BytesToKey' discards 
qualifiers from pointer target type


gcc -fPIC -g -O2  -I. -I../.. -I/home/riffraff/ruby-1.8.3 
-I/home/riffraff/ruby-1.8.3/ext/openssl -DHAVE_UNISTD_H 
-DHAVE_SYS_TIME_H -DHAVE_ASSERT_H -DHAVE_OPENSSL_SSL_H 
-DHAVE_OPENSSL_CONF_API_H -DHAVE_BN_PSEUDO_RAND_RANGE 
-DHAVE_BN_RAND_RANGE -DHAVE_VA_ARGS_MACRO  -c ossl_pkey_rsa.c
ossl_pkey_rsa.c: In function `ossl_rsa_to_der':
ossl_pkey_rsa.c:238: warning: assignment from incompatible pointer type
ossl_pkey_rsa.c:240: warning: assignment from incompatible pointer type


There are no special warning flags so maybe this is something that 
should be *really* checked, but my C-fu is close to nil, though sorry 
for not checking myself.

All test run fine, anyway.
More data:

linux 2.4.19
ruby 1.8.3 (2005-05-12) [i686-linux]
gcc version 2.95.4 20011002 (Debian prerelease)
OpenSSL 0.9.6c 21 dec 2001

(old stuff, but I'm just a guest on this box so I don't know why)