+dnl Usage: TL_AC_GXX_INCLUDE_DIR
+dnl
+dnl Set $gxx_include_dir to the location of the installed C++ include
+dnl directory. The value depends on $gcc_version and the configuration
+dnl options --with-gxx-include-dir and --enable-version-specific-runtime-libs.
+dnl
+dnl If you change the default here, you'll need to change the gcc and
+dnl libstdc++-v3 subdirectories too.
+AC_DEFUN([TL_AC_GXX_INCLUDE_DIR],
+[
+case "${with_gxx_include_dir}" in
+ yes)
+ AC_MSG_ERROR([--with-gxx-include-dir=[[dir]] requires a directory])
+ ;;
+ no | "")
+ case "${enable_version_specific_runtime_libs}" in
+ yes) gxx_include_dir='${libsubdir}/include/c++' ;;
+ *)
+ libstdcxx_incdir=c++/${gcc_version}
+ gxx_include_dir='${prefix}/include/'${libstdcxx_incdir} ;;
+ esac ;;
+ *) gxx_include_dir=${with_gxx_include_dir} ;;
+esac
+AC_SUBST(gxx_include_dir)
+AC_SUBST(libstdcxx_incdir)
+])