[R] strptime() keeps emitting warnings after establishing a handler with tryCatch()

[David Kepplinger]

Thanks, Rui, for checking on your end. I don't think any Linux-based
system is affected, as they silently ignore invalid timezone
identifiers (at least the versions I know of).

I now also had a chance to test on Windows 10 and get the same errors
as under macOS. The session info for this test is

> sessionInfo()
R version 4.0.2 (2020-06-22)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 19041)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252
[2] LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United States.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] compiler_4.0.2

I also tested a bit more and it seems that attaching handlers really
messes up `strptime()`. For example, `strptime()` stops to emit any
warning for invalid timezone identifiers:

> tryCatch(strptime('2020-10-31 18:30', format = '%Y-%m-%d %H:%M', tz = 'Wrong Timezone!'),
+                   warning = function (w) { stop("Error") })
Error in value[[3L]](cond) : Error
> # The following calls with a wrong timezone identifier don't emit any warnings anymore?!
> strptime('2020-10-31 18:30', format = '%Y-%m-%d %H:%M', tz = 'Wrong Timezone!')
[1] "2020-10-31 18:30:00"

But a subsequent call to `strptime()` with a valid timezone identifier
does emit the original warning (continuing the R session from above):

> strptime('2020-10-31 18:30', format = '%Y-%m-%d %H:%M', tz = 'GMT')
[1] "2020-10-31 18:30:00 GMT"
Warning messages:
1: In strptime("2020-10-31 18:30", format = "%Y-%m-%d %H:%M", tz = "GMT") :
  unknown timezone 'Wrong Timezone!'

And the next call with an incorrect tz identifier, doesn't emit a
warning, but uses the timezone from the previous call (continuing the
R session as above):

> strptime('2020-10-31 18:30', format = '%Y-%m-%d %H:%M', tz = 'Wrong Timezone!')
[1] "2020-10-31 18:30:00 GMT"

Best wishes,
David


On Sun, Nov 1, 2020 at 9:51 AM Rui Barradas <ruipbarradas using sapo.pt> wrote:
>
> Hello,
>
> I cannot reproduce this behavior and, as documented, the posted code
> doesn't issue warnings due to a wrong timezone but I'm running
>
>
> sessionInfo()
> R version 4.0.3 (2020-10-10)
> Platform: x86_64-pc-linux-gnu (64-bit)
> Running under: Ubuntu 20.04.1 LTS
>
> Matrix products: default
> BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.9.0
> LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.9.0
>
> locale:
>   [1] LC_CTYPE=pt_PT.UTF-8       LC_NUMERIC=C
>   [3] LC_TIME=pt_PT.UTF-8        LC_COLLATE=pt_PT.UTF-8
>   [5] LC_MONETARY=pt_PT.UTF-8    LC_MESSAGES=pt_PT.UTF-8
>   [7] LC_PAPER=pt_PT.UTF-8       LC_NAME=C
>   [9] LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=pt_PT.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_4.0.3
>
>
> Hope this helps,
>
> Rui Barradas
>
> Às 23:55 de 31/10/20, David Kepplinger escreveu:
> > Dear list members,
> >
> > I have come about a peculiar behavior in R (4.0.2) which I would
> > describe as a bug.
> > On macOS, where `strptime()` raises a warning for invalid timezone
> > identifiers, the following code will continue to raise the original
> > warning with every subsequent call to `strptime()`:
> >
> > ```
> > # attach a handler for warnings for this call only:
> > tryCatch(strptime('2020-10-31 18:30', format = '%Y-%m-%d %H:%M', tz =
> > 'Wrong Timezone!'),
> >                    warning = function (w) { stop("Error") })
> > # but every subsequent call will emit the original warning ("unknown
> > timezone 'Wrong Timezone!'")
> > strptime('2020-10-31 18:30', format = '%Y-%m-%d %H:%M', tz = 'Europe/Vienna')
> > strptime('2020-10-31 18:30', format = '%Y-%m-%d %H:%M', tz = 'GMT')
> > ```
> >
> > The output of the code above in R 4.0.2 on macOS is:
> >
> >> tryCatch(strptime('2020-10-31 18:30', format = '%Y-%m-%d %H:%M', tz = 'Wrong Timezone!'),
> > +                   warning = function (w) { stop("Error") })
> > Error in value[[3L]](cond) : Error
> >>
> >> strptime('2020-10-31 18:30', format = '%Y-%m-%d %H:%M', tz = 'Europe/Vienna')
> > [1] "2020-10-31 18:30:00 CET"
> > Warning message:
> > In strptime("2020-10-31 18:30", format = "%Y-%m-%d %H:%M", tz =
> > "Europe/Vienna") :
> >    unknown timezone 'Wrong Timezone!'
> >> strptime('2020-10-31 18:30', format = '%Y-%m-%d %H:%M', tz = 'GMT')
> > [1] "2020-10-31 18:30:00 GMT"
> > Warning messages:
> > 1: In strptime("2020-10-31 18:30", format = "%Y-%m-%d %H:%M", tz = "GMT") :
> >    unknown timezone 'Wrong Timezone!'
> >
> > The corresponding R session info is:
> >
> >> sessionInfo()
> > R version 4.0.2 Patched (2020-07-13 r78838)
> > Platform: x86_64-apple-darwin17.0 (64-bit)
> > Running under: macOS Catalina 10.15.7
> >
> > Matrix products: default
> > BLAS:   /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRblas.dylib
> > LAPACK: /Library/Frameworks/R.framework/Versions/4.0/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_4.0.2
> >
> >
> > I get the same odd behavior when attaching calling handlers with
> > `withCallingHandlers()`.
> > On RHEL 7 and Cent OS 6, which both don't issue warnings for invalid
> > timezones, the above code works.
> >
> > I don't see anything wrong with the code itself, but maybe I am
> > missing something. Any input would be appreciated.
> >
> > Best wishes,
> > David
> >
> > ______________________________________________
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> >