CODEWITHSUNDEEP
makefilegnu-make
Sparkler
Sparkler

Reputation: 2913

How to exclude a few files in an implicit makefile rule?

I am building several "main" files and currently have the following implicit rule:

$(PROJECT_ROOT)build/%.bin: $(PROJECT_ROOT)obj/%.o $(DEPS)
    @mkdir -p $(dir $@)
    @g++ -o $@ $^

Now I need to have special linking instructions for some of the "main" files. I defined the exceptions as follows:

SPECIAL_TARGET_1 = $(PROJECT_ROOT)build/...
SPECIAL_TARGET_2 = $(PROJECT_ROOT)build/...
SPECIAL_TARGETS = $(SPECIAL_TARGET_1) $(SPECIAL_TARGET_2)

and tried to filter them out as follows:

$(filter-out $(SPECIAL_TARGETS), $(PROJECT_ROOT)build/%.bin): $(PROJECT_ROOT)obj/%.o $(DEPS)
    @mkdir -p $(dir $@)
    @g++ -o $@ $^

but the filter-out is not filtering anything.

What is the correct way of exluding a few files from an implicit rule?

Upvotes: 1

Views: 474

Answers (1)

Joseph Quinsey
Joseph Quinsey

Reputation: 9962

The filter-out function is used to remove things from a list. But you do not have a list: you only have the single text string $(PROJECT_ROOT)build/%.bin.

If you were to add the new rule:

$(SPECIAL_TARGETS):
    @echo TODO I need to write some special linking instructions for $@

then this specific rule will override the generic pattern-matching rule.

Upvotes: 1

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