+ # We have a compiler and we are in a native configuration, bootstrap is ok
+ yes:$build:$build:yes | yes:$build:$build:lean)
+ ;;
+
+ # Other configurations, but we have a compiler. Assume the user knows
+ # what he's doing.
+ yes:*:*:yes | yes:*:*:lean)
+ AC_MSG_WARN([trying to bootstrap a cross compiler])
+ ;;
+
+ # No compiler: if they passed --enable-bootstrap explicitly, fail
+ no:*:*:yes | no:*:*:lean)
+ AC_MSG_ERROR([cannot bootstrap without a compiler]) ;;
+
+ # Fail if wrong command line
+ *)
+ AC_MSG_ERROR([invalid option for --enable-bootstrap])
+ ;;
+esac
+
+# Adjust the toplevel makefile according to whether bootstrap was selected.