Locating archived package binaries

I'm trying to renv::restore() on a macOS-Intel, R 4.1, and I'm running into trouble with RcppArmadillo version I can't install from source — there are some compiler errors, and sorting those out is completely beyond my skillset.

Some web searching uncovered this forum thread, which pointed me to Posit Package Manager. The forum thread gave the example https://packagemanager.posit.co/cran/2023-10-31/bin/windows/contrib/4.3/xfun_0.40.zip: using the Package manager, find a date when the old package version was current, plug that into the URL, and you can retrieve a binary. Opening that URL in my browser downloads a zip archive that, I assume, contains the correct binary.

In my case, the url should be something like https://packagemanager.posit.co/cran/2022-08-17/bin/macosx/contrib/4.1/RcppArmadillo_0. The date there is the day before the next version of RcppArmadillo was released. But that 404s. I get the same 404 if I try the day of and the day after version was released.

Any idea how I can locate this archived binary?

I would try using the Posit Public Package Manager UI to search for binary packages:

I'm not sure if a binary package for that package version will exist on Posit Public Package Manager (p3m.dev) since macOS binary package support was introduced in August of 2023. You can see that there is binary support for the current version.

Yes, that's exactly what I did to come up with the non-functional URL. I guess the 404 is because the version I need predates the macOS binary archive. Do you know of some other archive for macOS package binaries?