[Rcpp-devel] Module compilation warnings with clang++/llvm

[Dirk Eddelbuettel]

Hi Rich,

On 22 March 2013 at 10:18, Rich FitzJohn wrote:
| Dear list,
| 
| When I compile Rcpp modules with clang, I see a number of warnings that seem to come from Rcpp.  Below is a small file containing a fairly useless module (test.cpp).  

"Stuff happens" :)

| test.cpp:
| 
| ---8<-----
| 
| #include <Rcpp.h>
| 
| class Foo {
| public:
|   Foo(double a) : a(a) {}
|   double run(double b) { return a+b; }
| private:
|   double a;
| };
| 
| RCPP_MODULE(test) {
|   Rcpp::class_<Foo>("Foo")
|     .constructor<double>()
|     .method("run", &Foo::run);
| }
| 
| ----->8---
| 
| 
| Compiling this with sourceRcpp (though obviously that won't finish because no attributes) or through R CMD SHLIB (with a local Makevars file following the Rcpp FAQ) generates warnings:
| 
| clang++ -I/Library/Frameworks/R.framework/Resources/include -I/Library/Frameworks/R.framework/Resources/include/x86_64 -DNDEBUG -I/Library/Frameworks/R.framework/Versions/2.15/Resources/library/Rcpp/include -Wall -ansi -pedantic -I/usr/local/include    -fPIC  -O2 -Wall -c test.cpp -o test.o
| In file included from test.cpp:1:
| In file included from /Library/Frameworks/R.framework/Versions/2.15/Resources/library/Rcpp/include/Rcpp.h:48:
| /Library/Frameworks/R.framework/Versions/2.15/Resources/library/Rcpp/include/Rcpp/XPtr.h:39:5: warning: delete called on
|       'Rcpp::CppProperty<Foo>' that has virtual functions but non-virtual destructor [-Wdelete-non-virtual-dtor]

I think that one was just fixed in SVN a few days ago.

|     delete obj ;   
|     ^
| /Library/Frameworks/R.framework/Versions/2.15/Resources/library/Rcpp/include/Rcpp/XPtr.h:50:44: note: in instantiation of function
|       template specialization 'Rcpp::standard_delete_finalizer<Rcpp::CppProperty<Foo> >' requested here
| template <typename T, void Finalizer(T*) = standard_delete_finalizer<T> >
|                                            ^
| /Library/Frameworks/R.framework/Versions/2.15/Resources/library/Rcpp/include/Rcpp/module/class.h:392:26: note: in instantiation of member
|       function 'Rcpp::S4_field<Foo>::S4_field' requested here
|                 out[i] = S4_field<Class>( it->second, class_xp ) ; 
|                          ^
| test.cpp:12:3: note: in instantiation of member function 'Rcpp::class_<Foo>::fields' requested here
|   Rcpp::class_<Foo>("Foo")
|   ^
| 1 warning generated.
| g++ -dynamiclib -Wl,-headerpad_max_install_names -undefined dynamic_lookup -single_module -multiply_defined suppress -L/usr/local/lib -o test.so test.o /Library/Frameworks/R.framework/Versions/2.15/Resources/library/Rcpp/lib/x86_64/libRcpp.a -F/Library/Frameworks/R.framework/.. -framework R -Wl,-framework -Wl,CoreFoundation
| 
| If I increase the warnings to the level that CRAN are apparently using (changing CXXFLAGS to -O2 -Wall -pedantic -Wconversion) I get pages and pages of warnings (not pasted here).  So far as I can see, these come from Rcpp, but if I'm doing anything wrong, I'd appreciate any pointers.

Well, patches are always welcome. I develop mostly with whatever g++ version
is current in the current Ubuntu release, right now g++ 4.7.2.  I do use
-Wall -pedantic and try to keep it 'clean'.  I simply don't use the compiler
you use all that much. So in that sense ... patches welcome.

Also, can you try the most current tarball from R-Forge [ goes checking ]
Grr, once again no tarball available.  Could you test from SVN?  Else I can
make the most recent tarball available from my site.

Dirk

| Versions and flag information below.
| 
| Thanks,
| Rich
| 
| 
| Makevars contains:
| CXX=clang++
| CC=clang
| CXXFLAGS=-O2 -Wall
| 
| Versions:
| 
| Apple clang version 4.0 (tags/Apple/clang-421.0.57) (based on LLVM 3.1svn)
| Target: x86_64-apple-darwin12.2.1
| Thread model: posix
| 
| Mac OS X 10.8 (Mountain Lion), Xcode 4.5.1
| 
| sessionInfo:
| R version 2.15.3 (2013-03-01)
| Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)
| 
| locale:
| [1] en_AU.UTF-8/en_AU.UTF-8/en_AU.UTF-8/C/en_AU.UTF-8/en_AU.UTF-8
| 
| attached base packages:
| [1] stats     graphics  grDevices utils     datasets  methods   base     
| 
| other attached packages:
| [1] Rcpp_0.10.2
| 
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-- 
Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com