[Rd] Warnings created during R_eval or R_tryEval not shown before R ending or R error.

[Ivan Krylov]

В Sun, 23 Apr 2023 13:33:16 -0400
Laurent Gautier <lgautier using gmail.com> пишет:

> When tracing what happens during an error I found that
> verrorcall_dflt() in src/main/errors.c calls PrintWarnings(). That
> function is not part of R's C-API though.

I've tried reading the source code and came to a similar conclusion.

PrintWarnings() is required for warnings() to work because it creates
the last.warning variable for warnings() to access. When driving an
embedded R, R_ReplDLLdo1() will call it for you between expressions it
processes, but there doesn't seem to be a way to call it yourself.

Interestingly, there is .Internal(printDeferredWarnings()) which
eventually calls PrintWarnings(), but it's not exported as an API, only
used in a few places like try().

Would it help to run with options(warn = 1)? I think that a different
code path is taken in this case, which should emit warnings even
without a working REPL. warnings() would still be empty, unfortunately.

-- 
Best regards,
Ivan