[R] Sub-day precision Date class must be converted to integers by floor, not ceil

[eitsupi]

I noticed that the conversion of Date type with sub-day precision is not correct. arrow package has the same problem (apache/arrow#44502).

d <- as.Date(-0.1)
d
#> [1] "1969-12-31"
as.vector(nanoarrow::as_nanoarrow_array(d))
#> [1] "1970-01-01"

^{Created on 2024-10-22 with reprex v2.1.1}

[paleolimbot]

I didn't know that was possible!

The fix is probably here:

https://github.com/apache/arrow-nanoarrow/blob/4e5cd91b2945a05ec69c8835acaefe2e872de36d/r/R/as-array.R#L262-L282

[eitsupi]

Thanks for quick response. Yeah, using as.integer() here seems to execute ceil, so it doesn't seem to convert as intended. (I noticed this because the same thing happened when I cast f64 to date32 type in polars)