R devel - Oct 2012 - identical() fails to compare isS4(<S4 instance>) to TRUE

> setClass("A", "integer")
 > isS4(new("A"))
[1] TRUE
 > identical(isS4(new("A")), TRUE)
[1] FALSE

 > sessionInfo()
R Under development (unstable) (2012-10-04 r60876)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
  [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
  [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
  [7] LC_PAPER=C                 LC_NAME=C
  [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base
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On 12-10-04 4:57 PM, Martin Morgan wrote:
>
>   > setClass("A", "integer")
>   > isS4(new("A"))
> [1] TRUE
>   > identical(isS4(new("A")), TRUE)
> [1] FALSE
>
>   > sessionInfo()
> R Under development (unstable) (2012-10-04 r60876)
> Platform: x86_64-unknown-linux-gnu (64-bit)
>
> locale:
>    [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
>    [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
>    [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
>    [7] LC_PAPER=C                 LC_NAME=C
>    [9] LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
I can confirm this in R-devel, but it doesn't happen in R-patched.  In 
R-devel, isS4 is returning a vector marked as LGLSXP, but containing the 
value 16, not the usual 1 for TRUE.

 > .Internal(inspect(isS4(new("A"))))
@4bfbed8 10 LGLSXP g0c1 [] (len=1, tl=0) 16

I'm not going to have time to track this down and fix it.

Duncan Murdoch