How do I put conditionals in makefile pattern rules? - makefile

Question

I have an included file for a makefile that has these rules:
$(OUT_DIR)/%.0: %.c
$(CC) $(CFLAGS) -c -o $# $<
$(CC) $(CFLAGS) -E -P $< -o $(OUT_DIR)/$<.preproc
$(CC) $(CFLAGS) -E -dD $< -o $(OUT_DIR)/$<.macros
Works great. But, for some targets, I only want this:
$(OUT_DIR)/%.0: %.c
$(CC) $(CFLAGS) -c -o $# $<
can I do something like this using a predefined (or command line) variable:
$(OUT_DIR)/%.0: %.c
$(CC) $(CFLAGS) -c -o $# $<
ifeq ($(CIFLAG), 1)
$(CC) $(CFLAGS) -E -P $< -o $(OUT_DIR)/$<.preproc
$(CC) $(CFLAGS) -E -dD $< -o $(OUT_DIR)/$<.macros
endif
I'm sure I can include a different file based on the CIFLAG value, but was hoping I could do it by modifying the pattern rule.
Any ideas?
Thanks!
I did as MadScientist suggested (thanks for the education) but don't get what I want. My file now appears as:
$(OUT_DIR)/%.0: %.c
$(CC) $(CFLAGS) -c -o $# $<
[ $(CI_BUILD) -eq 0 ] \
|| {$(CC) $(CFLAGS) -E -P $< -o $(OUT_DIR)/$<.preproc \
&& $(CC) $(CFLAGS) -E -dD $< -o $(OUT_DIR)/$<.macros; }
But, when I execute, I get this (lots of irrelevant output trimmed):
cc -c -o test.o
[ 1 -eq 0 ] \
|| {cc -E -P test.c -o test.c.preproc \
&& cc -E -dD test.c -o test.c.macros; }
/bin/sh: -c: line 2: syntax error near unexpected token '}'
Is the ';' a problem?

Answer 1

You mustn't indent the Make conditional with tabs:
$(OUT_DIR)/%.0: %.c
$(CC) $(CFLAGS) -c -o $# $<
ifeq ($(CIFLAG), 1)
$(CC) $(CFLAGS) -E -P $< -o $(OUT_DIR)/$<.preproc
$(CC) $(CFLAGS) -E -dD $< -o $(OUT_DIR)/$<.macros
endif
See bullet 4: https://www.gnu.org/software/make/manual/html_node/Recipe-Syntax.html

Answer 2

You cannot use make conditionals like ifeq in the recipe passed to the shell, because the shell runs the recipe not make. You can use shell conditionals:
$(OUT_DIR)/%.0: %.c
$(CC) $(CFLAGS) -c -o $# $<
[ ($(CIFLAG) -ne 1 ] \
|| { $(CC) $(CFLAGS) -E -P $< -o $(OUT_DIR)/$<.preproc \
&& $(CC) $(CFLAGS) -E -dD $< -o $(OUT_DIR)/$<.macros; }
Of course, you haven't discussed how you plan to set the CIFLAG variable for some targets but not others...

Answer 3

I was able to make it work by changing the code to:
$(OUT_DIR)/%.0: %.c
$(CC) $(CFLAGS) -c -o $# $<
if [ ($(CIFLAG) -ne 1 ]; then \
$(CC) $(CFLAGS) -E -P $< -o $(OUT_DIR)/$<.preproc; \
$(CC) $(CFLAGS) -E -dD $< -o $(OUT_DIR)/$<.macros; fi