st.h requires stdlib.h
st.h is using size_t which is defined in stdlib.h.
Compilation fails when using st.h directly. That happens in libxml-ruby for example.
Updated by cfis (Charlie Savage) over 11 years ago
An aside, but libxml-ruby shouldn't be using st.h anymore (it did for a release but I took it out). Will check the header files to make sure.
FYI - the code that I did have in failed on 64bit machines, most likely because of this incorrect typecase. I can dig up the code if needed, its in the svn repository for libxml-ruby.