在gcc makefile中按降序对目标文件进行排序

Question

In my Makefile currently all the object files are sorted alphabetically using

OBJECTS =$(sort $(OBJECTS_UNSORTED)) in Makefile.

I want to sort the files in descending order Is there is a way possible to it? Tried the below options but they do not work -

OBJECTS =$((sort -r) $(OBJECTS_UNSORTED))

Answer 1

There is no simple way to reverse the order of a list of words built into GNU make.

You can either use the shell's sort function to do it, like this:

OBJECTS := $(shell for w in $(OBJECTS_UNSORTED); do echo $$w; done | sort -r)

Or, you can create a recursive function macro in GNU make to do it, like this:

reverse = $(if $1,$(call reverse,$(wordlist 2,999999,$1)) $(firstword $1))

OBJECTS := $(call reverse,$(sort $(OBJECTS_UNSORTED)))

Answer 2

This can be achieved by defining a function that prepends a word to a variable. By calling this function for each word of a variable that holds sorted words, the words are effectively reversed:

OBJECTS_SORTED := $(sort $(OBJECTS))

define Prepend
OBJECTS_SORTED_REVERSE := $1 $(OBJECTS_SORTED_REVERSE)
endef

$(foreach variable,$(OBJECTS_SORTED),$(eval $(call Prepend,$(variable))))

$(info $(OBJECTS_SORTED_REVERSE))