On Mon, 2017-03-20 at 16:38 +0100, Jeroen Ooms wrote: > On Sun, Mar 19, 2017 at 9:09 PM, Martyn Plummer <plumm...@iarc.fr> > wrote: > > I have just added some code to ensure that the compilation fails > > with an informative error message if a specific C++ standard is > > requested but the corresponding compiler has not been defined. > > Please test this. > > Are you sure we shouldn't just fall back on a previous standard > instead of failing? For example if the package author has specified a > preference for CXX14 but the compiler only has CXX11, the package > might still build with -std=c++11 (given that C++14 is only a small > extension on the C++11 standard). > > The current behavior (in R 3.3) for packages with "CXX_STD=CXX11" is > to fall back on CXX when the compiler does not have CXX1X.
I don't think that is true. > Will R-3.4 > start failing these packages? This would affect many users on CentOS 6 > (gcc 4.4.7). The major issue with long-term support platforms like CentOS is that the compiler is rather old. According to the GCC web site, 4.4.7 has partial support for C++11 via the -std=c++0x flag ( https://gcc.gnu.org /projects/cxx-status.html#cxx11 ). The problem is that the tests for C++11 compliance used by R's configure script have become much more stringent. If g++ 4.4.7 passed before, it is unlikely to pass now. This is an issue that I discussed here. https://bugs.r-project.org/bugzilla/show_bug.cgi?id=17189 This creates a regression on older platforms. Some packages that used only a few C++11 features used to compile correctly but now don't because the compiler is no longer recognized as conforming to the C++11 standard (and to be fair it never did but the previous tests were weaker). What I suggest is that on these platforms you do a post-install patch of etc/Makeconf and set the variables for the C++11 compiler manually (CXX11, CXX11FLAGS, CXX11PICFLAGS, CXX11STD, SHLIB_CXX11LD, SHLIB_CXX11LDFLAGS). Martyn ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
