More informative message when install warnings are converted to errors

[gaborcsardi]

E.g. mention the env var to change this behavior.

[stroberts]

Building on this:
It appears that the environment variable which controls (or can control) this behavior is 'R_REMOTES_NO_ERRORS_FROM_WARNINGS'. So if one does not want warnings to arrest an installation, they would execute something along the lines of
allow_warnings_not_to_break <- Sys.setenv(R_REMOTES_NO_ERRORS_FROM_WARNINGS = T)
before running remotes::install_.

That's my reading given the use of should_error_for_warnings().

Certainly I think this behavior needs better documentation.

[gaborcsardi]

You need to set it to true, see https://github.com/r-lib/remotes#environment-variables

[gaborcsardi]

Turns out that this is not so easy, because the warning -> error conversion happens in the subprocess.

[gaborcsardi]

Closing for now, as there will be other improvements related to this:

• R-devel has some improvements to avoid broken installations. https://bugs.r-project.org/bugzilla/show_bug.cgi?id=17478 The warning->error conversion is hopefully not needed (as much) with these in place.
• We'll also work on handling the DLL locking issue better, soon Work around the infamous locked DLL issue #368.