2

我有一个 Makefile：

#Build Configurations
CONFIGS = Debug Release Profile

#Config flags
Debug_Flags=dasd
Release_Flags=

.SECONDEXPANSION:

#Debug_safety_check Release_safety_check Profile_safety_check targets
$(addsuffix _safety_check,$(CONFIGS)):
#Check existence of variable
ifeq '$(origin $(subst safety_check,FLAGS,$@))' 'undefined'
    $(error $(subst safety_check,FLAGS,$@) variable undefined)
endif 

#How to make our configurations (do corresponding safety_checks)
$(CONFIGS): $$@_safety_check

此行不正确：

ifeq '$(origin $(subst safety_check,FLAGS,$@))' 'undefined'

我认为，这是因为在调用相应的安全检查时发生了 $@扩展。但是 ifeq 扩展“立即”发生，所以，事实上，我们得到这样的行：

ifeq '$(origin ' ') 'undefined'

是否存在某种从列表中检查变量定义的方法？

4

1 回答 1

1

呃，明白了。

#Build Configurations
CONFIGS = Debug Release Profile

#Config flags
Debug_Flags=dasd
Release_Flags=
#Profile_Flags=

#Adds _flags suffix for each variable, 
#get it's origin ('undefined' for undefined variables).
#If $(findstring) a lookup for the word 'undefined' succeeds, 
#adds to the result variable
undef_flags = $(foreach c, $(CONFIGS), \
                $(if $(findstring undefined, $(origin $c_Flags)), $c))

#Count words for undefined configs, must be not '0'
ifneq ($(words $(undef_flags)),0)
#strip because if flag is undefined we'll get the trash spaces
$(error Flags ($(strip $(undef_flags))) must be defined)
endif
于 2012-10-17T15:45:26.830 回答