[R-SIG-Mac] R 3.4.2 on High Sierra (10.13)

[Prof Brian Ripley]

[Repeating for convenient reference a comment in an earlier thread.]

R 3.4.2 was in code freeze when High Sierra as released, and so there 
was no opportunity to make and test workarounds for undocumented changes 
to the latter.

R will be unable to find the system timezone on High Sierra (confirmed 
with the CRAN 3.4.2 release):

 > Sys.timezone()
[1] NA
 > .leap.seconds
  [1] "1972-07-01 GMT" "1973-01-01 GMT" "1974-01-01 GMT" "1975-01-01 GMT"
  [5] "1976-01-01 GMT" "1977-01-01 GMT" "1978-01-01 GMT" "1979-01-01 GMT"
  [9] "1980-01-01 GMT" "1981-07-01 GMT" "1982-07-01 GMT" "1983-07-01 GMT"
[13] "1985-07-01 GMT" "1988-01-01 GMT" "1990-01-01 GMT" "1991-01-01 GMT"
[17] "1992-07-01 GMT" "1993-07-01 GMT" "1994-07-01 GMT" "1996-01-01 GMT"
[21] "1997-07-01 GMT" "1999-01-01 GMT" "2006-01-01 GMT" "2009-01-01 GMT"
[25] "2012-07-01 GMT" "2015-07-01 GMT" "2017-01-01 GMT"
Warning message:
In as.POSIXlt.POSIXct(x, tz) : unknown timezone 'default/Europe/London'


Perhaps the best workaround is to use R-patched from 
http://r.research.att.com/ .  However, in almost all cases a workaround 
is to set TZ, either outside the session (not so easy for R.app) or at 
the beginning of the session by e.g.

Sys.setenv(TZ = "Europe/London")

(where the correct value will be obvious from running the code above).

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Emeritus Professor of Applied Statistics, University of Oxford