Different behaviour for unrecognized timezones between `with_tz` and `force_tz`

[atsyplenkov]

When an unrecognised timezone is passed to the tzone argument of the with_tz() and force_tz(), the behaviour of functions is different. First just returns a warning and does nothing, while the latter aborts.

I am just curious if there is any hidden logic for this. Why cannot both of them just throw warnings or errors?

library(lubridate)
#> 
#> Attaching package: 'lubridate'
#> The following objects are masked from 'package:base':
#> 
#>     date, intersect, setdiff, union
library(quickcheck)

df <- data.frame(
  time = posixct_() |> show_example()
)

# Behaviour is similar
force_tz(df$time, tzone = "US/Alaska")
#> [1] "2116-11-19 08:52:58 AKST" "0571-11-09 16:05:56 LMT" 
#> [3] "0988-09-08 09:54:51 LMT"
with_tz(df$time, tzone = "US/Alaska")
#> [1] "2116-11-18 10:52:58 AKST" "0571-11-09 18:27:16 LMT" 
#> [3] "0988-09-08 12:16:11 LMT"

# Both aborts but with different error messages
force_tz(df$time, tzone = NA)
#> Error in if (length(tz) == 1L && tz == tzout) {: missing value where TRUE/FALSE needed
with_tz(df$time, tzone = NA)
#> Error: Invalid input type, expected 'character' actual 'logical'

# Behaviour is different
force_tz(df$time, tzone = "foo")
#> Error in C_force_tz(to_posixct(time), tz, roll_dst): CCTZ: Unrecognized output timezone: "foo"
with_tz(df$time, tzone = "foo")
#> Warning in with_tz.default(df$time, tzone = "foo"): Unrecognized time zone
#> 'foo'
#> Warning in as.POSIXlt.POSIXct(x, tz): unknown timezone 'foo'
#> [1] "2116-11-18 19:52:58 GMT" "0571-11-09 04:26:52 GMT"
#> [3] "0988-09-07 22:15:47 GMT"

^{Created on 2025-03-31 with reprex v2.1.1}

[etiennebacher]

Simpler reprex:

library(lubridate, warn.conflicts = FALSE)

date <- as.Date("2025-03-31")
with_tz(date, tzone = "foo")
#> Warning in with_tz.default(date, tzone = "foo"): Unrecognized time zone 'foo'
#> [1] "2025-03-31 foo"
force_tz(date, tzone = "foo")
#> Error in C_force_tz(to_posixct(time), tz, roll_dst): CCTZ: Unrecognized output timezone: "foo"