Hi,
I am trying to implement on a Win7 box the showArgs example of section 5.10.2
"Calling .External" of the R extension manual. I am using interchangeably gcc
(RTools) and Visual C++ (via Makefile.win) to build a package. I get a couple
of runtime oddities when the dll compiled with Visual C++. I'd value comments,
observations and tips from interested readers. I tried my best to find proper
compilation settings for VCPP, from a variety of source incl. Duncan Murdoch's
advice.
Cheers,
J-M
OBSERVATIONS
============
1/ The for() loop does not hit the termination condition on args being
R_NilValue, and ends up stuck on pointers as shown below, equality never
reached.
args 0x020e24a0 SEXPREC *
R_NilValue 0x835425ff SEXPREC *
2/ If I force it out of the endless loop, after the function returns, I get a
nasty "Unhandled exception at 0x6c799419 in Rgui: 0xC0000005: Access violation
writing location 0x0009eee9." with a call stack as follow. I did check that the
cdecl calling convention is used.
R.dll!6c799419()
[Frames below may be incorrect and/or missing, no symbols loaded for
R.dll]
R.dll!6c797736()
user32.dll!7633cd90()
user32.dll!7636c1c2()
Rgraphapp.dll!63551cba()
CODE
====
// R code
library(showArgs)
blah = as.Date('2000-01-01')
printArgs(a=1:3, b=LETTERS[1:3], blah=blah)
// END R code
// C/Cpp code:
extern "C" { // because I compile the code 'as C++' for Visual C++, for in-code
variable declaration
SEXP __cdecl showArgs_ext(SEXP args);
}
SEXP __cdecl showArgs_ext(SEXP args)
{
// snip
args = CDR(args); /* skip 'name' */
for(int i = 0; args != R_NilValue; i++, args = CDR(args)) {
// verbatim from the manual
}
return R_NilValue;
}
// END C/Cpp code
Vcc Compilation settings:
/I"C:\bin\R\R\include" /ZI /nologo /W3 /WX- /Od /Oy- /D "_WINDLL" /D "_MBCS"
/Gm /EHsc /RTC1 /GS /fp:precise /Za /Zc:wchar_t /Zc:forScope
/Fp"Debug\showArgs.pch" /Fa"Debug\" /Fo"Debug\" /Fd"Debug\vc100.pdb" /Gd /TP
/analyze- /errorReport:queue
/OUT:"C:\XXXX\Debug\showArgs.dll" /NOLOGO /LIBPATH:"C:\bin\R\R\bin\i386" /DLL
"Rdll.lib" "kernel32.lib" "user32.lib" "gdi32.lib" "winspool.lib"
"comdlg32.lib" "advapi32.lib" "shell32.lib" "ole32.lib" "oleaut32.lib"
"uuid.lib" "odbc32.lib" "odbccp32.lib" /DEF:"showArgs-win.def" /MANIFEST
/ManifestFile:"Debug\showArgs.dll.intermediate.manifest" /ALLOWISOLATION
/MANIFESTUAC:"level='asInvoker' uiAccess='false'" /DEBUG
/PDB:"C:\XXXX\Debug\showArgs.pdb" /PGD:"C:\XXXX\Debug\showArgs.pgd" /TLBID:1
/DYNAMICBASE /NXCOMPAT /MACHINE:X86 /ERRORREPORT:QUEUE
ENVIRONMENT
===========
- Windows 7 32 bits
- R version 2.15.0 (2012-03-30) Platform: i386-pc-mingw32/i386 (32-bit)
- RTools 2.15.0
- MS Visual Cpp 2010 (express edition)
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