为什么要锁起来?

# check debug xdc
define check_debug_xdc
    if [ -f ${DEBUG_XDC} ]; then \
        ...
    fi
endef   

如果直接打电话的话,就让它跑得好。

# Optimize
${OUTPUTS1}: ${INPUTS1}
    @echo ""
    @echo "Optimization"
    @date '+%Y_%m%d_%H%M'
    @$(call check_debug_xdc)  

但是如果我注释掉DEBUG XDC和put $(call check_debug_xdc)

# DEBUG_XDC     = ./fpga_ila/fpga_ila.srcs/constrs_1/new/${TOP}.xdc  
...
# Optimize
${OUTPUTS1}: ${INPUTS1}
    @echo ""
    @echo "Optimization"
    @date '+%Y_%m%d_%H%M'
    @if [ ! -z "${DEBUG_XDC}" ]; then $(call check_debug_xdc); fi  

尝试make-dn,它打印下面的消息,然后停止响应。

GNU Make 3.81
Copyright (C) 2006  Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.

This program built for i686-pc-linux-gnu
Reading makefiles...
Reading makefile `makefile'...
Updating makefiles....
 Considering target file `makefile'.
    ...
         Finished prerequisites of target file `fpga/fpga_opt.dcp'.
        Must remake target `fpga/fpga_opt.dcp'.

如何修复?