CODEWITHSUNDEEP
makefile
Him
Him

Reputation: 5551

Conditional statements using Make

I'm having a problem with conditional statements in make. Existing questions on SO only work on the highest level in the Makefile.

Here's what I have:

.PHONY: all

all: bar/*.o

bar/%.o: foo/%.cc
ifeq (,$(wildcard $(@D)))
    @echo $(wildcard $(@D))
endif

There are two empty files under foo, a.cc and b.cc. The folder bar exists.

Here's the output:

PS C:\Users\cbrown2\Src> mingw32-make
bar
bar

It enters the ifeq statement, even though $(wildcard $(@D)) gives bar.

What gives?

Upvotes: 0

Views: 205

Answers (1)

Renaud Pacalet
Renaud Pacalet

Reputation: 28945

You cannot use conditionals this way. When make evaluates your conditional automatic variables don't have a value yet. So make will see:

bar/%.o: foo/%.cc
    @echo $(wildcard $(@D))

because $(@D) expands as the empty string. And when make will pass the recipe to the shell it will first expand $(@D) which, this time, has a value: bar.

One side note that has nothing to do with your problem: when bar does not contain all object files yet,

all: bar/*.o

will not do what you probably want. What you probably want is:

SRC := $(wildcard foo/*.cc)
OBJ := $(patsubst foo/%.cc,bar/%.o,$(SRC))

all: $(OBJ)

Upvotes: 1

Related Questions