[Rd] byte-compiler bug

[luke-tierney at uiowa.edu]

Thanks for the report. Fixed in R_devel with r72631; I'll port to
R-patched later today or tomorrow.

The default setting and how to get the current settings are documented
in the Details section of the enableJIT help page at the end of the
paragraph for enableJIT.

Best,

luke

On Wed, 26 Apr 2017, Hervé Pagès wrote:

> Hi,
>
> I'm running into a case where byte-compilation changes
> the semantic of a function. This is with R 3.4.0:
>
>   foo <- function(x) { TRUE && x }
>
>   foo(c(a=FALSE))
>   # [1] FALSE          # OK
>
>   foo(c(a=TRUE))
>   # [1] TRUE           # OK
>
>   foo(c(a=FALSE))
>   #     a              # ????
>   # FALSE
>
> The 3rd call returned a result that it different from the 1st
> call!
>
> After scratching my head for a while, I found out that there
> is a lot going on:
>
>   1) When calling foo the first 2 times, the function is not
>      byte-compiled so is behaving as expected.
>
>   2) However after the 2nd call, the function gets automatically
>      compiled. This seems to be a new feature in R 3.4.0 but
>      you'll have to grep the NEWS file to find out (search for
>      JIT). The man page for cmpfun/enableJIT nicely explains
>      the JIT levels but I couldn't find anywhere that the level
>      is set to 3 by default. I don't even know how one is
>      supposed to get the current level. Calling enableJIT() to
>      change the level returns a value, and this value might
>      look like the previous level, but this is undocumented and
>      it returns 0 instead of 3 the 1st time I call it anyway.
>
>   3) There is some bug in the byte-compiler that seems to make it
>      treat `&&` like if it were `&` when compiling foo.
>
> Cheers,
> H.
>
> > sessionInfo()
> R version 3.4.0 (2017-04-21)
> Platform: x86_64-pc-linux-gnu (64-bit)
> Running under: Ubuntu 16.04.2 LTS
>
> Matrix products: default
> BLAS: /home/biocbuild/bbs-3.5-bioc/R/lib/libRblas.so
> LAPACK: /home/biocbuild/bbs-3.5-bioc/R/lib/libRlapack.so
>
> 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=en_US.UTF-8       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
>
> loaded via a namespace (and not attached):
> [1] compiler_3.4.0
>
>

-- 
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa                  Phone:             319-335-3386
Department of Statistics and        Fax:               319-335-3017
    Actuarial Science
241 Schaeffer Hall                  email:   luke-tierney at uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu