Makefile : how to increment a variable when you call it? (var++ in bash)

Question

Here is part of my makefile :

LISTEINC = $(DEST)/file.inc $(DEST)/otherfile.inc $(DEST)/anotherfile.inc
compteur = 1

$(DEST)/file: $(LISTEINC)
       #action

$(DEST)/%.inc: $(DEST)/%.jpg
      ./script $< $compteur $(DEST) > $@

How to have the variable compteur at 1 for file, 2 for otherfile, 3 for anotherfile?

$((compteur++)) would work in bash script, but here I really don't know what the equivalent is. I tried many combination of $$ () ++ +1 etc... Nothing worked. Anyone could help me please?

Answer 1

It can be done with eval :

$(eval compteur=$(shell echo $$(($(compteur)+1))))

From the manual :

The eval function is very special: it allows you to define new makefile constructs that are not constant; which are the result of evaluating other variables and functions. The argument to the eval function is expanded, then the results of that expansion are parsed as makefile syntax. The expanded results can define new make variables, targets, implicit or explicit rules, etc