Upgrade build/test environment to use R 4.0 and Roxygen2 7.1.1

[exalate-issue-sync]

R 4.0 was released in April, so it’s time for us to start officially support it. We should start using R 4.0 for our build environment and also add it as a secondary test environment (in addition to R 3.5).

In R 4.0, they are getting more strict about the R documentation and we found that our current Rdocs are not compliant (we link to some "topics" and not "pages" and that's no longer allowed). There is a work-around which allows us to keep the same links that we have (which from a user perspective, it's more sensible to link to the precise topic vs a general page). Someone patched roxygen2 to allow the old type of docs links to still exist (and it will fix it automatically), so if we upgrade our build environment to build artifacts with roxygen2 v7.1.1, we will be good. If not, we are going to have to patch all releases manually if they want to go on CRAN. This has held up the last CRAN release and we are still not on CRAN with 3.30.0.6 yet

At the same time, we should update our test envivonment to test on both R 3.5 and R 4.0 so if there are any issues we will see them. Before I submit to CRAN, I double check our release on all the required environments (different versions of R and different OS) and so I will see any problems, but then it's a pain to manually patch the release (or wait for the next fix release), so better to catch the issues in our own test environment if possible.

Things to do:

• docker images for R4.0
• test stages
• update docs

[exalate-issue-sync]

Jan Sterba commented: [~accountid:557058:afd6e9a4-1891-4845-98ea-b5d34a2bc42c] could you please verify that the latest master release is CRAN-compatible?

[h2o-ops]

JIRA Issue Migration Info

Jira Issue: PUBDEV-7673
Assignee: Jan Sterba
Reporter: Erin LeDell
State: Resolved
Fix Version: 3.30.1.1
Attachments: N/A
Development PRs: Available

Linked PRs from JIRA

#4787