+# Whether to enable the internal docs build.
+#
+# This takes quite some time due to the generation of lots of call
+# graphs, so it is disabled by default.
+set_enable_internal_docs=no
+AC_ARG_ENABLE([internal-docs], [dnl
+AS_HELP_STRING([--enable-internal-docs],
+[Build internal code docs if doxygen available])], [dnl
+dnl If either --enable-foo nor --disable-foo were given, execute this.
+ if test "x$enableval" = xno \
+ || test "x$enableval" = xoff \
+ || test "x$enableval" = xfalse;
+ then
+ set_enable_internal_docs=no
+ elif test "x$enableval" = xyes \
+ || test "x$enableval" = xon \
+ || test "x$enableval" = xtrue
+ then
+ set_enable_internal_docs=yes
+ fi
+])
+AC_MSG_CHECKING([whether to create internal code docs])
+AC_MSG_RESULT([${set_enable_internal_docs}])
+AM_CONDITIONAL([ENABLE_INTERNAL_DOCS], [test "x${set_enable_internal_docs}" = "xyes"])
+