On Sun, Feb 03, 2013 at 01:02:04PM -0800, Paul Eggert wrote: > On 02/02/2013 06:01 PM, Roger Leigh wrote: > > The attached patch introduces three macros: > > AC_CXX_CONSTEXPR > > AC_CXX_FINAL > > AC_CXX_NULLPTR > > which behave like AC_C_CONST et al but are for the new > > C++11 constextr, final and nullptr keywords. > > Sorry, I don't know C++, so I'm not really qualified to judge > the utility of these macros or of Miles's qualms about them, > but would his comments be addressed by Autoconf macros that > cause config.h to #define HAVE_CONSTEXPR rather than #defining > constexpr, etc.? Or would that just be too awkward? I guess > I don't know the usage scenario here. My initial intention was that my substituting the keyword with nothing, it would transparently allow code to build on non C++11 compilers. HAVE_* would permit the user to do this themselves if appropriate. However, after looking into this a bit more, I'm becoming less sure of the utility. In the case of nullptr, it's a type in its own right (std::nullptr_t) which can be used to influence template specialisation. So the substitution could easily break code. Likewise for constexpr and final. > > Would including macros such as AC_CXX_MEMORY, AC_CXX_TUPLE, > > AC_CXX_REGEX etc. be acceptable? > > Is the pattern the same for all these? If so, it sounds > like it'd be better to have one macro AC_CXX_STD and invoke > it via AC_CXX_STD([memory]), AC_CXX_STD([tuple]), etc. > Even if there are slight differences it still may be better > to have one "smart" macro rather than lots of macros with > repetitive innards. The pattern is roughly the same. However... each needs a bunch of different types importing into the std namespace, so it's not /that/ slight. And for some (e.g. regex) the headers are currently bust in GCC libstdc++ so need to be coupled with a proper test instatiating and using the types to make sure they work. We could certainly have a generic function like AC_C_STD_TRY we pass all the details to. Regards, Roger -- .''`. Roger Leigh : :' : Debian GNU/Linux http://people.debian.org/~rleigh/ `. `' schroot and sbuild http://alioth.debian.org/projects/buildd-tools `- GPG Public Key F33D 281D 470A B443 6756 147C 07B3 C8BC 4083 E800 _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx https://lists.gnu.org/mailman/listinfo/autoconf
