+ cygwin*)
+ # Full C++ conformance when using a shared libstdc++-v3 requires some
+ # support from the Cygwin DLL, which in more recent versions exports
+ # wrappers to aid in interposing and redirecting operators new, delete,
+ # etc., as per n2800 #17.6.4.6 [replacement.functions]. Check if we
+ # are configuring for a version of Cygwin that exports the wrappers.
+ if test x$host = x$target; then
+ AC_CHECK_FUNC([__wrap__Znaj],[gcc_ac_cygwin_dll_wrappers=yes],[gcc_ac_cygwin_dll_wrappers=no])
+ else
+ # Can't check presence of libc functions during cross-compile, so
+ # we just have to assume we're building for an up-to-date target.
+ gcc_ac_cygwin_dll_wrappers=yes
+ fi
+ AC_DEFINE_UNQUOTED(USE_CYGWIN_LIBSTDCXX_WRAPPERS,
+ [`if test $gcc_ac_cygwin_dll_wrappers = yes; then echo 1; else echo 0; fi`],
+ [Define if you want to generate code by default that assumes that the
+ Cygwin DLL exports wrappers to support libstdc++ function replacement.])
+ esac
+ case $target_os in