ABI stability

[jaimergp]

Dear team,

I am packaging this library for conda-forge and I would like to know if there are any promises with respect to ABI stability:

• Yes, there is an ABI contract tied to the minor version (e.g. kept during the 3.2.x series, but might be different for 3.3.0)
• Yes, there is an ABI contract tied to the major version (e.g. kept during the 3.x series, but might be different for 4.0)
• No contract

Thanks!