What is need to build native extension for Gems on Windows? (RubyGems)

More and more gems I run into requires building "native extensive", such as RedCloth. Are there tools that are open-source or free that is sufficient to do that? I heard MS Visual Studio also has a free version. Will that be开发者_如何学JAVA enough to build native extensions?

If you installed Ruby with the RubyInstaller (as you should), then the DevKit has everything you need.

If you use the obsolete MSVC6 builds, then you need to install Microsoft Visual C++ 6.0, because newer versions of MSVC are incompatible. Good luck finding that, though, MSVC6 isn't even from this millenium.