Exploring the evolution of functions/parameters in base R over time.
This was a crude experiment to figure out if it would be possible to use package sources to infer the functions and their signatures exposed in an R package.
We compare to rcheology as the "gold standard." Overall, this approach was able to get fairly close to rcheology's performance without the cost of having to install the package and inspect it in a live environment. This is appealing because it would be more computationally viable for a CI approach and you don't have to deal with the headaches of trying to get every package to install (obscure dependencies, platform-dependant, etc.).
This work has been put on hold for now. The reasoning is that the number of functions that people are likely to actually use that have changed in recent versions of R is pretty small. (See backports for a package that tries to cover all of the motivating changes.)
The current recomendation is to exercise unit tests in CI on the oldest version of R that you intend to support. Unfortunately, this won't catch errors in your code that aren't covered in unit tests, but it would at least cover some of the code.
https://github.com/hughjonesd/apicheck for a nascent package trying to do something similar.
This was intended to grow into an R package (hence the structure) but it never did. The interesting bits are all RMD files in inst/. Start with https://github.com/trestletech/rdocs/blob/master/inst/parse-rs.Rmd (or see the pre-rendered HTML adjacent) and branch into the other RMDs in that directory to do more analysis.
Alternatively, if you just want the output of this work, see https://github.com/trestletech/rdocs/blob/master/inst/parsed_rd.rds which represents the best I could do at identifying functions and their signature using package sources in base R since version 3.0.0.
> head(parsed_rd, n=10)
ver pkg file fun class paramName placeholder evaluated defunct exported
1 3.0.0 base abbreviate.Rd abbreviate <NA> names.arg <NA> TRUE FALSE FALSE
2 3.0.0 base abbreviate.Rd abbreviate <NA> minlength 4 TRUE FALSE FALSE
3 3.0.0 base abbreviate.Rd abbreviate <NA> use.classes TRUE TRUE FALSE FALSE
4 3.0.0 base abbreviate.Rd abbreviate <NA> dot FALSE TRUE FALSE FALSE
5 3.0.0 base abbreviate.Rd abbreviate <NA> strict FALSE TRUE FALSE FALSE
6 3.0.0 base abbreviate.Rd abbreviate <NA> method c("left.kept", "both.sides") TRUE FALSE FALSE
7 3.0.0 base agrep.Rd agrep <NA> pattern <NA> TRUE FALSE FALSE
8 3.0.0 base agrep.Rd agrep <NA> x <NA> TRUE FALSE FALSE
9 3.0.0 base agrep.Rd agrep <NA> max.distance 0.1 TRUE FALSE FALSE
10 3.0.0 base agrep.Rd agrep <NA> costs NULL TRUE FALSE FALSE