`entrace()` alters warning message line returns

[jmbarbone]

rlang::entrace() is removing line returns.

• a single line return (i.e., \n) is replaced with a space (i.e., )
• a two or more line returns (e.g., \n\n, \n\n\n\n) are reduces to just a double return (i.e., \n\n)

packageVersion("rlang")
#> [1] '1.1.7'

get_message <- function(message, handler) {
  tryCatch(
    withCallingHandlers(
      warning(message, call. = FALSE),
      warning = handler
    ),
    warning = conditionMessage
  )
}

# single
get_message("zero\none\ntwo", force)
#> [1] "zero\none\ntwo"
get_message("zero\none\ntwo", rlang::entrace)
#> [1] "zero one two"

# double, multiple
get_message("zero\n\none\n\n\n\ntwo", force)
#> [1] "zero\n\none\n\n\n\ntwo"
get_message("zero\n\none\n\n\n\ntwo", rlang::entrace)
#> [1] "zero\n\none\n\ntwo"


withCallingHandlers(
  warning("zero\none\ntwo", call. = FALSE),
  warning = force
)
#> Warning: zero
#> one
#> two

withCallingHandlers(
  warning("zero\none\ntwo", call. = FALSE),
  warning = rlang::entrace
)
#> Warning: zero one two

^{Created on 2026-02-01 with reprex v2.1.1}