[Rcpp-devel] R CMD check not happy about -std=c++0x

| I'm getting a warning when I try to build my CPP package that depends on 
| Rcpp and uses the classic Makevars :
| 
| PKG_CXXFLAGS=`Rcpp:::CxxFlags()` -I.
| PKG_LIBS=`Rcpp:::LdFlags()`
| 
| 
| I get this warning from R CMD check :
| 
| * checking for portable compilation flags in Makevars ... WARNING
| Non-portable flags in variable 'PKG_CXXFLAGS':
|    -std=c++0x

I also noticed that yesterday working on another package using Rcpp.  I think
we need to fix this.

Recall that 'can use Cxx0x' should be based on the compiler used to build R
(!!) not Rcpp or the current package.  So we need to query 'R CMD config CXX'
at build time and somehow remember that.

| Is there a workaround ? We probably would then have to update the new 
| skeleton generator to use it.

Right.

Three out of two people have difficulties with fractions.