a is a data.frame with a Date column.

a <- data.frame(date = as.Date("2015-06-07"))

When serialised and deserialised with readr's write_csv and read_csv, the resulting data.frame b_tbl is equal to a according to base:::all.equal.default, but not according to dplyr:::all.equal.tbl_df:

b_tbl <- readr::read_csv(readr::write_csv(a, path = ""))
b <- dplyr:::as.data.frame.tbl_df(b_tbl)
a_tbl <- dplyr:::as.tbl(a)
dplyr:::all.equal.tbl_df(a_tbl, b_tbl)
# "Incompatible type for column date: x Date, y Date"
base:::all.equal.default(a_tbl, b_tbl)
# TRUE
base:::all.equal.default(a, b)
 # TRUE
dplyr:::all.equal.tbl_df(a, b)
# "Incompatible type for column date: x Date, y Date"

I would expect all 4 all.equal statements above to return TRUE.

Note that this occurs only if b_tbl is the result of a write_csv and read_csv, so I am not sure whether the issue is related to readr or dplyr, but the inconsistency shows in dplyr:

dplyr:::all.equal.tbl_df(a_tbl, a)
# TRUE