Re: [Monotone-devel] implement hash_map with std::tr1

[Zack Weinberg]

On 7/16/06, Benoît Dejean <address@hidden> wrote:
> Le dimanche 30 avril 2006 à 19:13 +0200, Benoît Dejean a écrit :
> > Le dimanche 30 avril 2006 à 05:55 -0700, Nathaniel Smith a écrit :
> > > On Sun, Apr 30, 2006 at 10:54:32AM +0200, Benoît Dejean wrote:
> > > > +#if defined(__GNUC__) && (__GNUC__ >= 4)
> > > >  #define HASHMAP_PRESENT
> > >
> > > This is the wrong way to do feature availability checks... can we use
> > > autoconf here instead?  (Especially because many compilers besides
> > > g++4 will have std::tr1 support, one hopes!)
> >
> > that's what i was thinking, but i don't know how.

Something like this:

AC_CACHE_CHECK([for tr1::unordered_map and tr1::unordered_set],
              ac_cv_cxx_tr1_unordered_map_and_set,
 [AC_LANG_PUSH(C++)
  AC_COMPILE_IFELSE(AC_LANG_SOURCE([
#include <tr1/functional>
#include <tr1/unordered_map>
#include <tr1/unordered_set>
using std::tr1::hash;
using std::tr1::unordered_map;
using std::tr1::unordered_set;
using std::tr1::unordered_multimap;
]),
     ac_cv_cxx_tr1_unordered_map_and_set=yes,
     ac_cv_cxx_tr1_unordered_map_and_set=no)
  AC_LANG_POP(C++)])
if test x$ac_cv_cxx_tr1_unordered_map_and_set = xyes; then
 AC_DEFINE(HAVE_TR1_UNORDERED_MAP_AND_SET, 1,
           [Define to 1 if your C++ compiler provides
tr1::unordered_map and tr1::unordered_set.])
fi

If you don't know what to do with this, you can check your changes in
on a branch as they are and announce that you've done so, and I'll add
the autoconf stuff on top.

Nathaniel, did you have any other issues with the original patch?

zw