>>>>> Martin Maechler
>>>>> on Wed, 12 Oct 2022 10:17:28 +0200 writes:
>>>>> Kurt Hornik
>>>>> on Tue, 11 Oct 2022 16:44:13 +0200 writes:
>>>>> Davis Vaughan writes:
>>> I've got a bit more information about this one. It seems like it
>>> (only? not sure) appears when `TZ = "UTC"`, which is why I didn't see
>>> it before on my Mac, which defaults to `TZ = ""`. I think this is at
>>> least explainable by the fact that those "optional" fields aren't
>>> technically needed when the time zone is UTC.
>> Exactly. Debugging `[<-.POSIlt` with
>> x <- as.POSIXlt(as.POSIXct("2013-01-31", tz = "America/Chicago"))
>> Sys.setenv(TZ = "UTC")
>> x[1] <- NA
>> shows we get into
>> value <- unclass(as.POSIXlt(value))
>> if (ici) {
>> for (n in names(x)) names(x[[n]]) <- nms
>> }
>> for (n in names(x)) x[[n]][i] <- value[[n]]
>> where
>> Browse[2]> names(value)
>> [1] "sec" "min" "hour" "mday" "mon" "year" "wday" "yday"
"isdst"
>> Browse[2]> names(x)
>> [1] "sec" "min" "hour" "mday" "mon" "year" "wday"
"yday"
>> [9] "isdst" "zone" "gmtoff"
>> Without having looked at the code, the docs say
>> ‘zone’ (Optional.) The abbreviation for the time zone in force at
>> that time: ‘""’ if unknown (but ‘""’ might also be used for
>> UTC).
>> ‘gmtoff’ (Optional.) The offset in seconds from GMT: positive
>> values are East of the meridian. Usually ‘NA’ if unknown,
>> but ‘0’ could mean unknown.
>> so perhaps we should fill with the values for the unknown case?
>> -k
> Well,
> I think you both know I'm in the midst of dealing with these
> issues, to fix both
> [.POSIXlt and
> [<-.POSIXlt
> Yes, one needs a way to not only "fill" the partially filled
> entries but also to *normalize* out-of-range values
> (say negative seconds, minutes > 60, etc)
> All this is available in our C code, but not on the R level,
> so yesterday, I wrote a C function to be called via .Internal(.)
> from a new R that provides this.
> Provisionally called
> balancePOSIXlt()
> because it both balances the 9 to 11 list-components of POSIXlt
> and it also puts all numbers of (sec, min, hour, mday, mon)
> into a correct range (and also computes correctl wday and yday numbers).
> but I'm happy for proposals of better names.
> I had contemplated validatePOSIXlt() as alternative, but then
> dismissed that as in some sense we now do agree that
> "imbalanced" POSIXlt's are not really invalid ..
> .. and yes, to Davis: Even though I've spent so many hours with
> POSIXlt, POSIXct and Date during the last week, I'm still
> surprised more often than I like by the effects of timezone
> settings there.
> Martin
I have committed the new R and C code now, defining balancePOSIXlt(),
to get feedback from the community.
I've extended the documentation in help(DateTimeClasses),
and notably factored out the description
of POSIXlt mentioning the "ragged" and "out-of-range" cases.
This needs more testing and experiments, and I have not
announced it NEWS yet.
Planned next is to use it in [.POSIXlt and [<-.POSIXlt
so they will work correctly.
But please share your thoughts, propositions, ...
Martin
>>> I can reproduce this now on my personal Mac:
>>> ```
>>> x <- as.POSIXlt(as.POSIXct("2013-01-31", tz = "America/Chicago"))
>>> Sys.setenv(TZ = "")
>>> x[1] <- NA
>>> x
>>> #> [1] NA
>>> x <- as.POSIXlt(as.POSIXct("2013-01-31", tz = "America/Chicago"))
>>> Sys.setenv(TZ = "America/New_York")
>>> x[1] <- NA
>>> x
>>> #> [1] NA
>>> x <- as.POSIXlt(as.POSIXct("2013-01-31", tz = "America/Chicago"))
>>> Sys.setenv(TZ = "UTC")
>>> x[1] <- NA
>>> #> Error in x[[n]][i] <- value[[n]] : replacement has length zero
>>> x
>>> #> [1] "2013-01-31 CST"
>>> ```
>>> Here are `sessionInfo()` and `Sys.getenv("TZ")` outputs for 3 GitHub
>>> Actions platforms where the bug exists (note they all set `TZ =
"UTC"`!):
>>> Linux:
>>> ```
>>>> sessionInfo()
>>> R version 4.2.1 (2022-06-23)
>>> Platform: x86_64-pc-linux-gnu (64-bit)
>>> Running under: Ubuntu 18.04.6 LTS
>>> Matrix products: default
>>> BLAS: /usr/lib/x86_64-linux-gnu/openblas/libblas.so.3
>>> LAPACK: /usr/lib/x86_64-linux-gnu/libopenblasp-r0.2.20.so
>>> locale:
>>> [1] LC_CTYPE=C.UTF-8 LC_NUMERIC=C LC_TIME=C.UTF-8
>>> [4] LC_COLLATE=C.UTF-8 LC_MONETARY=C.UTF-8 LC_MESSAGES=C.UTF-8
>>> [7] LC_PAPER=C.UTF-8 LC_NAME=C LC_ADDRESS=C
>>> [10] LC_TELEPHONE=C LC_MEASUREMENT=C.UTF-8 LC_IDENTIFICATION=C
>>> attached base packages:
>>> [1] stats graphics grDevices utils datasets methods base
>>> loaded via a namespace (and not attached):
>>> [1] compiler_4.2.1
>>>> Sys.getenv("TZ")
>>> [1] "UTC"
>>> ```
>>> Mac:
>>> ```
>>>> sessionInfo()
>>> R version 4.2.1 (2022-06-23)
>>> Platform: x86_64-apple-darwin17.0 (64-bit)
>>> Running under: macOS Big Sur ... 10.16
>>> Matrix products: default
>>> BLAS:
>>>
/Library/Frameworks/R.framework/Versions/4.2/Resources/lib/libRblas.0.dylib
>>> LAPACK:
>>>
/Library/Frameworks/R.framework/Versions/4.2/Resources/lib/libRlapack.dylib
>>> locale:
>>> [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
>>> attached base packages:
>>> [1] stats graphics grDevices utils datasets methods base
>>> loaded via a namespace (and not attached):
>>> [1] compiler_4.2.1
>>>> Sys.getenv("TZ")
>>> [1] "UTC"
>>> ```
>>> Windows:
>>> This is the best I can get you, sorry (remote worker issues), but note
that
>>> it does also say `tz UTC` like the others.
>>> ```
>>> version R version 4.2.1 (2022-06-23 ucrt)
>>> os Windows Server x64 (build 20348)
>>> system x86_64, mingw32
>>> ui RTerm
>>> language (EN)
>>> collate English_United States.utf8
>>> ctype English_United States.utf8
>>> tz UTC
>>> date 2022-10-11
>>> ```
>>> And here is my Mac where the bug doesn't show up by default because `TZ
=
>>> ""`:
>>> ```
>>>> sessionInfo()
>>> R version 4.2.1 (2022-06-23)
>>> Platform: x86_64-apple-darwin17.0 (64-bit)
>>> Running under: macOS Big Sur ... 10.16
>>> Matrix products: default
>>> BLAS:
>>>
/Library/Frameworks/R.framework/Versions/4.2/Resources/lib/libRblas.0.dylib
>>> LAPACK:
>>>
/Library/Frameworks/R.framework/Versions/4.2/Resources/lib/libRlapack.dylib
>>> locale:
>>> [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
>>> attached base packages:
>>> [1] stats graphics grDevices utils datasets methods base
>>> loaded via a namespace (and not attached):
>>> [1] compiler_4.2.1
>>>> Sys.getenv("TZ")
>>> [1] ""
>>>> Sys.timezone()
>>> [1] "America/New_York"
>>> ```
>>> -Davis
>>> On Thu, Oct 6, 2022 at 9:33 AM Davis Vaughan <da...@rstudio.com> wrote:
>>>> Hi all,
>>>>
>>>> I have found another POSIXlt bug while I've been fiddling around with
it.
>>>> This one only appears on specific OSes, because it has to do with the
fact
>>>> that the `gmtoff` field is optional, and isn't always used on all
OSes. It
>>>> also doesn't seem to be specific to r-devel, I think it has been there
>>>> awhile.
>>>>
>>>> Here is the bug:
>>>>
>>>> ```
>>>> x <- as.POSIXlt(as.POSIXct("2013-01-31", tz = "America/Chicago"))
>>>>
>>>> # Oh no!
>>>> x[1] <- NA
>>>> #> Error in x[[n]][i] <- value[[n]] : replacement has length zero
>>>> ```
>>>>
>>>> If you look at the objects, you can see that `x` has a `gmtoff` field,
but
>>>> `NA` (when converted to POSIXlt, which is what `[<-.POSIXlt` does)
does not:
>>>>
>>>> ```
>>>> unclass(x)
>>>> #> $sec
>>>> #> [1] 0
>>>> #>
>>>> #> $min
>>>> #> [1] 0
>>>> #>
>>>> #> $hour
>>>> #> [1] 0
>>>> #>
>>>> #> $mday
>>>> #> [1] 31
>>>> #>
>>>> #> $mon
>>>> #> [1] 0
>>>> #>
>>>> #> $year
>>>> #> [1] 113
>>>> #>
>>>> #> $wday
>>>> #> [1] 4
>>>> #>
>>>> #> $yday
>>>> #> [1] 30
>>>> #>
>>>> #> $isdst
>>>> #> [1] 0
>>>> #>
>>>> #> $zone
>>>> #> [1] "CST"
>>>> #>
>>>> #> $gmtoff
>>>> #> [1] -21600
>>>> #>
>>>> #> attr(,"tzone")
>>>> #> [1] "America/Chicago" "CST" "CDT"
>>>>
>>>> unclass(as.POSIXlt(NA))
>>>> #> $sec
>>>> #> [1] NA
>>>> #>
>>>> #> $min
>>>> #> [1] NA
>>>> #>
>>>> #> $hour
>>>> #> [1] NA
>>>> #>
>>>> #> $mday
>>>> #> [1] NA
>>>> #>
>>>> #> $mon
>>>> #> [1] NA
>>>> #>
>>>> #> $year
>>>> #> [1] NA
>>>> #>
>>>> #> $wday
>>>> #> [1] NA
>>>> #>
>>>> #> $yday
>>>> #> [1] NA
>>>> #>
>>>> #> $isdst
>>>> #> [1] -1
>>>> #>
>>>> #> attr(,"tzone")
>>>> #> [1] "UTC"
>>>> ```
>>>>
>>>> The problem seems to be that `[<-.POSIXlt` assumes that if the field
was
>>>> there in `x` then it must also be there in `value`:
>>>>
>>>>
https://github.com/wch/r-source/blob/e10a971dee6a0ab851279c183cc21954d66b3be4/src/library/base/R/datetime.R#L1303-L1304
>>>>
>>>> But this isn't the case for the `NA` value that was converted to
POSIXlt.
>>>>
>>>> I can't reproduce this on my personal Mac, but it affects the Linux,
Mac,
>>>> and Windows machines we use for the lubridate CI checks through GitHub
>>>> Actions.
>>>>
>>>> Thanks,
>>>> Davis
>>>>
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