R devel - Jul 2016 - failed to assign RegisteredNativeSymbol for splitString

I saw a warning from R that I don't fully understand.  Here's one way
to reproduce it:

  $ /usr/local/pkg/R-3.2-branch-20160718/bin/R --version | head -n 3 
  R version 3.2.5 Patched (2016-05-05 r70929) -- "Very, Very Secure
Dishes"
  Copyright (C) 2016 The R Foundation for Statistical Computing 
  Platform: x86_64-pc-linux-gnu/x86_64 (64-bit) 
   
  $ /usr/local/pkg/R-3.2-branch-20160718/bin/R --vanilla --no-restore --no-save
--silent
  > splitString <- function(...) { print("Test, do nothing") } 
  > invisible(tools::toTitleCase) 
  Warning message: 
  failed to assign RegisteredNativeSymbol for splitString to splitString since
splitString is already defined in the 'tools' namespace

Another way to trigger that warning is by loading the knitr package, e.g.:

  > require("knitr") 
  Loading required package: knitr 
  Warning: failed to assign RegisteredNativeSymbol for splitString to
splitString since splitString is already defined in the 'tools'
namespace

The warning only happens the FIRST time I run any code that triggers it.
To get it to happen again, I need to restart R.

R 3.1.0 and all earlier versions do not throw that warning, because
they do not have any splitString C function (see below) at all.  R
3.2.5 does throw the warning, and I believe 3.3 and all later versions
of R do also (but I cannot currently test that on this machine).

In my case, normally I start R without "--vanilla", and load various
custom libraries of my own, one of which contained an R function
"splitString".  That gave the exact same symptoms as the simpler way
of reproducing the warning above.  In practice, I solved the problem
by renaming my "splitString" function to something else.  But I still
wonder what exactly was going on with that warning.

I noticed that the toTitleCase() R code calls .Call() with a bare
splitString identifier, no quotes around it:

  $ grep -n splitString R-3-[234]*/src/library/tools/R/utils.R
  R-3-2-branch/src/library/tools/R/utils.R:1988:        xx <-
.Call(splitString, x, ' -/"()')
  R-3-3-branch/src/library/tools/R/utils.R:2074:        xx <-
.Call(splitString, x, ' -/"()\n')
  R-3-4-trunk/src/library/tools/R/utils.R:2074:        xx <-
.Call(splitString, x, ' -/"()\n')

  $ find R-3-4-trunk -name .svn -prune -o -type f -print0 | xargs -0 grep -n
splitString
  R-3-4-trunk/src/library/tools/R/utils.R:2074:        xx <-
.Call(splitString, x, ' -/"()\n')
  R-3-4-trunk/src/library/tools/src/text.c:264:SEXP splitString(SEXP string,
SEXP delims)
  R-3-4-trunk/src/library/tools/src/tools.h:45:SEXP splitString(SEXP string,
SEXP delims);
  R-3-4-trunk/src/library/tools/src/init.c:53:    CALLDEF(splitString, 2),

Doing that is perfectly legal according to help(".Call"), and
interestingly, it apparently does NOT matter whether that code puts
quotes around the splitString or not - I tried it, and it made no
difference.

Is it generally the case the users MUST NOT define R functions with
the same names as "registered" C functions?  Will something break if
we do?

-- 
Andrew Piskorski <atp at piskorski.com>

On 07/18/2016 03:45 PM, Andrew Piskorski wrote:
> I saw a warning from R that I don't fully understand.  Here's one
way
> to reproduce it:
>
>    $ /usr/local/pkg/R-3.2-branch-20160718/bin/R --version | head -n 3
>    R version 3.2.5 Patched (2016-05-05 r70929) -- "Very, Very Secure
Dishes"
>    Copyright (C) 2016 The R Foundation for Statistical Computing
>    Platform: x86_64-pc-linux-gnu/x86_64 (64-bit)
>
>    $ /usr/local/pkg/R-3.2-branch-20160718/bin/R --vanilla --no-restore
--no-save --silent
>    > splitString <- function(...) { print("Test, do
nothing") }
>    > invisible(tools::toTitleCase)
>    Warning message:
>    failed to assign RegisteredNativeSymbol for splitString to splitString
since splitString is already defined in the 'tools' namespace
>
> Another way to trigger that warning is by loading the knitr package, e.g.:
or

   splitString = NULL; loadNamespace("tools")

Thanks, it's a bug fixed with

------------------------------------------------------------------------
r70933 | morgan | 2016-07-18 16:35:39 -0400 (Mon, 18 Jul 2016) | 5 lines

assignNativeRoutines looks only in package namespace

- previously looked for symbols in inherited environments
- https://stat.ethz.ch/pipermail/r-devel/2016-July/072909.html

------------------------------------------------------------------------

>
>    > require("knitr")
>    Loading required package: knitr
>    Warning: failed to assign RegisteredNativeSymbol for splitString to
splitString since splitString is already defined in the 'tools'
namespace
>
> The warning only happens the FIRST time I run any code that triggers it.
> To get it to happen again, I need to restart R.
>
> R 3.1.0 and all earlier versions do not throw that warning, because
> they do not have any splitString C function (see below) at all.  R
> 3.2.5 does throw the warning, and I believe 3.3 and all later versions
> of R do also (but I cannot currently test that on this machine).
>
> In my case, normally I start R without "--vanilla", and load
various
> custom libraries of my own, one of which contained an R function
> "splitString".  That gave the exact same symptoms as the simpler
way
> of reproducing the warning above.  In practice, I solved the problem
> by renaming my "splitString" function to something else.  But I
still
> wonder what exactly was going on with that warning.
>
> I noticed that the toTitleCase() R code calls .Call() with a bare
> splitString identifier, no quotes around it:
>
>    $ grep -n splitString R-3-[234]*/src/library/tools/R/utils.R
>    R-3-2-branch/src/library/tools/R/utils.R:1988:        xx <-
.Call(splitString, x, ' -/"()')
>    R-3-3-branch/src/library/tools/R/utils.R:2074:        xx <-
.Call(splitString, x, ' -/"()\n')
>    R-3-4-trunk/src/library/tools/R/utils.R:2074:        xx <-
.Call(splitString, x, ' -/"()\n')
>
>    $ find R-3-4-trunk -name .svn -prune -o -type f -print0 | xargs -0 grep
-n splitString
>    R-3-4-trunk/src/library/tools/R/utils.R:2074:        xx <-
.Call(splitString, x, ' -/"()\n')
>    R-3-4-trunk/src/library/tools/src/text.c:264:SEXP splitString(SEXP
string, SEXP delims)
>    R-3-4-trunk/src/library/tools/src/tools.h:45:SEXP splitString(SEXP
string, SEXP delims);
>    R-3-4-trunk/src/library/tools/src/init.c:53:    CALLDEF(splitString, 2),
>
> Doing that is perfectly legal according to help(".Call"), and
> interestingly, it apparently does NOT matter whether that code puts
> quotes around the splitString or not - I tried it, and it made no
> difference.
>
> Is it generally the case the users MUST NOT define R functions with
> the same names as "registered" C functions?  Will something break
if
> we do?
>

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