character method for as_date forces `tz` arg when `format` present, doesn't use it

[ClaytonJY]

If you try to convert a string using lubridate::as_date while specifying the format, you must also set tz, but it isn't used.

library(lubridate)
#> 
#> Attaching package: 'lubridate'
#> The following object is masked from 'package:base':
#> 
#>     date

x <- "05172018"

as_date(x)
#> Warning: All formats failed to parse. No formats found.
#> [1] NA

as_date(x, format = "%m%d%Y")
#> Error in strptime(x, format, tz): invalid 'tz' value

as_date(x, tz = "America/New_York", format = "%m%d%Y")
#> [1] "2018-05-17"

tz(.Last.value)
#> [1] "UTC"

Current Github version, 1.7.4.

On the one hand, this is unexpected, surprising behavior, but on the other hand, do timezones ever matter for Date's?

In the very least, seems like you shouldn't need the tz arg here; the second option should work.

[vspinu]

Indeed, should be fixed.

as_date is not an idiomatic parser btw. Use mdy for this particular case.

[ClaytonJY]

per discussion on #675 should as_date have its tz arg removed?

[hadley]

Minimal reprex:

library(lubridate, warn.conflicts = FALSE)
x <- "05172018"

as_date(x)
#> Warning: All formats failed to parse. No formats found.
#> [1] NA

as_date(x, format = "%m%d%Y")
#> Error in strptime(x, format, tz): invalid 'tz' value

as_date(x, tz = "America/New_York", format = "%m%d%Y")
#> [1] "2018-05-17"

^{Created on 2019-11-19 by the reprex package (v0.3.0)}