`@includeRmd` needs to pass fixed width to `rmarkdown::render()`

[DavisVaughan]

And maybe other reproducible global options?

Probably around here? https://github.com/r-lib/roxygen2/blob/include-rmd-warning/R/rd-include-rmd.R#L52-L68

Context is that in vctrs @lionel- and I keep overwriting each other when we document() the package. In particular, files included by @includeRmd seem to change with respect to the width depending on who is calling document(). Here is an example where the git history of theory-faq-coercion.Rd shows us overwriting each other.
https://github.com/r-lib/vctrs/commits/main/man/theory-faq-coercion.Rd

The changes look something like this

[gaborcsardi]

It could certainly do that, but it'll still be annoying that when you knit the Rmd from the IDE, then width will not apply. (And the output of that might be cached and re-used by roxygen2.)

So I am afraid that the only reliable way to set these parameters is from the Rmd itself.

FWIW the roxygen2 default can also be set with something like this (untested) in man/roxygen/meta.R:

list(
  markdown = TRUE,
  knitr_chunk_options = list(
    R.options = list(width = 80)
  )
)

(and you can remove Roxygen: from DESCRIPTION.

(It is probable that if you set R.options yourself in the Rmd for some reason, then you'll have to repeat width = 80 there, I don't think knitr will merge the two sets of options.)