Autodetect if Rmd is rendered via @includeRmd

[dfalbel]

I wonder if cli could autodetect if the Rmd is running through an @includeRmd tag and thus being included in an . Rd file and in this case set cli.unicode=FALSE.

Otherwise, the Rmd can end-up rendering unicode characters in the .Rd and generate issues when building the PDF manual:

LaTeX errors when creating PDF version.
This typically indicates Rd problems.
LaTeX errors found:
! Package inputenc Error: Unicode char ─ (U+2500)
(inputenc)                not set up for use with LaTeX.

For example:

https://github.com/mlverse/luz/blob/f8a34dcc815651456ece210dcdcd60b4e97ebc8d/man/evaluate.Rd#L63

[gaborcsardi]

Yeah, this is annoying. There is currently no official way to detect roxygen2, so we would need to address this there first.

This is also related: r-lib/roxygen2#1240

Ideally, we would have Unicode in the HTML help and in pkgdown, and would only turn it off in the PDF manual.

For now, a workaround is to turn it off before the @includeRmd:

#' Test
#'
#' `r options(cli.unicode = FALSE)`
#'
#' @includeRmd test.Rmd
#' @name test
NULL

This of course turns it off for the whole session, but if you run document() is a subprocess or from the shell, then it is not too bad.

[gaborcsardi]

We actually still need support from roxygen2 for this.

[hadley]

Now part of r-lib/roxygen2#1349