How to compile sqlite3, mysql and postgres driver for Rails 3.X on Mac OS X Leopard?

Is there a reason why all sqlite3, mysql, postgres driver compiles on Mac OS X Leopard when it is Rails 2.3.8, but can't compile when it is Rails 3.x?

Theoretically, isn't it just some compile flags to make them work?

(They all compile on Snow Leopard with the latest Xcode, but can't compile with Leopard with a slightly older Xcode... it really isn't that old, not like a compiler from 1998, just from 2007/20开发者_开发技巧08.)

I'm running Leopard with Xcode 3.1.2 and ruby 1.8.7 and 1.9.2 and had no problems with the pg adapter. You jut have to have the pg_config application in your system PATH. I've installed from the binary package at the EnterpriseDB Site and added the directory /Library/PostgreSQL/9.0/bin to the path.

I've also never had problems with the sqlite3 driver. With MySQL I have to little experience.