[R] Add debug output to r/configure in case of failure

[assignUser]

Describe the enhancement requested

We have already enabled printing of the complete cmake log in case of a build issue. We should do something similar for the test compile command in r/configure (and potentially other places in that file that are ambious with their error messages?)

Component(s)

R

[paleolimbot]

As noted on Zulip, a failed download would also be good to log by default!

[assignUser]

#38769 has an interesting failure

• the build failes because the downloaded cmake binary can't be found in the build script (this also happened on the cran builder when testing the source build) I don't know why? Maybe some config leads to the R temp dir being cleaned out when the bash script is started or something?
• the source build/nixlibs.R fail but that doesn't kill the entire package install, which of course leads to confusion... I also saw this on the failed windows build where even though nixlib.R should have closed via q(status=1) the build continued.

[paleolimbot]

I think there is somewhere in the either nixlibs.R or configure that is swallowing an error and continuing, which probably means that the MacOS check failure also happens earlier than the test compile stage (we just don't know what it is because we don't produce any output).

I think we should probably enable all output at this point: at one point we were trying to actively suppress output that would raise eyebrows with respect to CRAN policy, but I think we are better off enabling all the output by default. We sent them an email telling them what we do: since they already know, the best thing we can do to respect their time (and ours) is to give enough output to reasonably diagnose an install failure.

[assignUser]

I think we should probably enable all output at this point

Yes totally agree

failure also happens earlier than the test compile stage

I actually don't think so (unless its in the unpack/unlink commands but those don't have errors or warning supressed so they should pop up). After the checksum validation nothing happens that could throw an error. There is code that checks/sets flags which could misbehave and cause the test compile error of course...