[R] R CMD SHLIB changes function name when compiling

[Prof Brian Ripley]

Is the file .c or .C?  You said .c, but then you said a .C file 
worked (which it should not have), and I wonder if you have this 
backwards.

A .c file is C, a .C file is C++ (in R 2.11.1 but not R 2.12.0).

extern "C" would be required if this were a C++ source, but we were 
told otherwise.

On Sat, 9 Oct 2010, Steve Pederson wrote:

> Hi Prof Ripley,
>
> Thanks for the response & the use of the correct terminology. I've checked 
> the environment variables & there is none set called CC.
>
> The .dll was definitely compiled using R CMD SHLIB. I'm not quite sure what 
> output you're referring to but at the command prompt when I enter:
>
> ...\bin> R CMD SHLIB summariseMCMC.C
>
> I get the output:
>
> g++ -I"C:/R/R-2.11.1/include"        -02 -Wall summariseMCMC.c 
> summariseMCMC.o
> g++ -shared -s -static-libgcc -o summariseMCMC.dll tmp.def summariseMCMC.0 
> -LC:/R/R-2.11.1/bin -1R

Exactly that -- g++ is a C++ compiler.

> Please let me know if I can try anything different provide any more useful 
> output.
>
> Another source file I have (runUniformMCMC.C) compiles & runs perfectly using 
> the same approach, so I'm rather perplexed as to why this one gets it's name 
> mangled. It originally had actual code in it that did useful things, but I 
> stripped it back while I was trying to figure out what is happening.
>
> Thanks again,
>
> Steve
>
>
> On 8/10/2010 8:06 PM, Prof Brian Ripley wrote:
>> On Fri, 8 Oct 2010, Steve Pederson wrote:
>> 
>>> Hi,
>>> 
>>> I'm trying to write a function in C for implementation with .Call.
>>> When compiling using R CMD SHLIB characters seem to be added to the
>>> function name.
>>> 
>>> Here's the complete C code from the file summariseMCMC.c:
>>> 
>>> #include<R.h>
>>> #include<Rdefines.h>
>>> #include<Rinternals.h>
>>> 
>>> void summariseMCMC(SEXP data) {
>>> 
>>> PROTECT(data=AS_NUMERIC(data));
>>> UNPROTECT(1);
>>> 
>>> }
>>> 
>>> Then after compiling (R CMD SHLIB summariseMCMC.c) & loading the .dll
>>> 
>>> dyn.load("C:/R/R-2.11.1/bin/summariseMCMC.dll")
>>> is.loaded("_Z13summariseMCMCP7SEXPREC")
>>> [1] TRUE
>>> is.loaded("summariseMCMC")
>>> [1] FALSE
>>> 
>>> Just wondering if anyone had any pointers for getting rid of this, or
>>> have I missed something outrageously obvious?
>> 
>> You have. This was not done by'R CMD SHLIB', but by a C++ compiler -- it
>> is called 'name mangling'. Unfortunately you didn't show us the output
>> from that command, when the cause would probably have been 'outrageously
>> obvious'.
>> 
>> The fix is to make sure you use a C compiler to compile C code, and
>> we've almost no idea why that is not being done on your system.
>> But as a guess, check that the environment variable CC is not set.
>> 
>>> 
>>> Thanks,
>>> 
>>> Steve
>>> 
>>> 
>>> sessionInfo()
>>> R version 2.11.1 (2010-05-31)
>>> i386-pc-mingw32
>>> 
>>> locale:
>>> [1] LC_COLLATE=English_Australia.1252 LC_CTYPE=English_Australia.1252
>>> [3] LC_MONETARY=English_Australia.1252 LC_NUMERIC=C
>>> [5] LC_TIME=English_Australia.1252
>>> 
>>> attached base packages:
>>> [1] stats graphics grDevices utils datasets methods base
>>> 
>>> other attached packages:
>>> [1] limma_3.4.4 Biobase_2.8.0 aroma.affymetrix_1.7.0
>>> [4] aroma.apd_0.1.7 affxparser_1.20.0 R.huge_0.2.0
>>> [7] aroma.core_1.7.0 aroma.light_1.16.0 matrixStats_0.2.1
>>> [10] R.rsp_0.3.6 R.cache_0.3.0 R.filesets_0.8.3
>>> [13] digest_0.4.2 R.utils_1.4.4 R.oo_1.7.3
>>> [16] R.methodsS3_1.2.0
>>> 
>>> loaded via a namespace (and not attached):
>>> [1] tools_2.11.1
>>> 
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>> 
>> 
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595