better re-balancing after subassigning POSIXlt

git-svn-id: https://svn.r-project.org/R/trunk@88441 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: maechler

doc/NEWS.Rd

@@ -234,6 +234,10 @@
 
       \item \code{hist(*, log = "x")} now works without a warning, thanks
       to \I{Martin Smith}'s \PR{18921}.
+
+      \item Subassigning \code{"POSIXlt"}, i.e., \code{<tdat>[i] <- val}
+      and \code{<tdat>[[i]] <- val} now rebalance as they should,
+      thanks to \I{Mikael Jagan}'s \PR{18919}.
     }
   }
 }

src/library/base/R/datetime.R

@@ -1328,7 +1328,11 @@ function(x, units = c("secs", "mins", "hours", "days", "months", "years"))
         ici <- is.character(i)
         nms <- names(x$year)
         if(mj) {
-            value <- unclass(as.POSIXlt(value))
+            tz <- attr(x, "tzone")
+            value <- unCfillPOSIXlt(
+                if(inherits(value, "POSIXlt") && identical(tz, attr(value, "tzone")))
+                    value
+                else as.POSIXlt(as.POSIXct(value), tz = tz[1L]))
             if(ici) {
                 for(n in names(x))
                     names(x[[n]]) <- nms
@@ -1562,15 +1566,19 @@ as.list.POSIXlt <- function(x, ...)
 `[[<-.POSIXlt` <- function(x, i, value)
 {
     cl <- oldClass(x)
-    class(x) <- NULL
+    class(x) <- unCfillPOSIXlt(x)
 
     if(!missing(i) && is.character(i)) {
         nms <- names(x$year)
         for(n in names(x))
             names(x[[n]]) <- nms
     }
 
-    value <- unCfillPOSIXlt(as.POSIXlt(value))
+    tz <- attr(x, "tzone")
+    value <- unCfillPOSIXlt(
+        if(inherits(value, "POSIXlt") && identical(tz, attr(value, "tzone")))
+            value
+        else as.POSIXlt(as.POSIXct(value), tz = tz[1L]))
     for(n in names(x))
         x[[n]][[i]] <- value[[n]]
 

tests/datetime3.R

@@ -763,6 +763,21 @@ assertErrV(seq(to=to, by=by))
 assertErrV(seq(from, to, by=by, length.out=length.out))
 
 
+## subassignment to POSIXlt must reconcile time zones - PR#18919
+tz <- "America/Toronto"
+if(!tz %in% OlsonNames()) {
+    cat(sprintf("%s not in time zone data base\n", tz))
+} else withAutoprint({
+    (x <- x1 <- x2 <- as.POSIXlt(.POSIXct(0, tz = "UTC")))
+    (y <- as.POSIXlt(.POSIXct(0, tz = tz)))
+    x1[1L] <- x2[[1L]] <- y
+    x1; x2
+    stopifnot(identical(x1, x), identical(x2, x))
+})
+## x1, x2 were identical but differing from x
+
+
+
 ## keep at end
 rbind(last =  proc.time() - .pt,
       total = proc.time())