consider updating RCPP_VERSION etc. automatically at build time

[kevinushey]

To help avoid things like #1019. It'd be nice to automate this (e.g. with a configure script) so that these fields are always populated as appropriate based the version in the DESCRIPTION file.

I don't think we need a full-blown autoconf script; rather, we could just use a simple configure / configure.win script to build e.g. config.h from config.h.in.

If I can toot my own horn, I would propose using configure to make this happen. Note that this would not require any explicit dependency on the configure package; the necessary infrastructure would be bundled into Rcpp itself.

Otherwise, it'd be simple to (say) have configure / configure.win scripts which merely sourced a helper R script that manages the configure process.

Let me know if this sounds worth doing.

[eddelbuettel]

Allow me to gently vote against. I also maintain maybe a dozen configure.ac across packages, but the one-time release process is different. I have set such things up in the past (e.g. RInside and littler stored a decade ago which SVN revision built the package) but I generally just use one-off scripts.

In this case, a one-off script to modify config.h would have helped. Then again when you look at the git log of that file I didn't miss all that often. So call it a 🤷‍♂️

Edit: I fell on a first pass for your configure not being configure but we both agree. A one-off script could help. I don't think I really need one but I will try to make some time to look into the configure-that-is-not-really-configure to see if it would help my workflow.