How can I configure my makefile for debug and release builds?

Question

I have the following makefile for my project, and I\'d like to configure it for release and debug builds. In my code, I have lots of #ifdef DEBUG macros in plac

Answer 1

This question has appeared often when searching for a similar problem, so I feel a fully implemented solution is warranted. Especially since I (and I would assume others) have struggled piecing all the various answers together.

Below is a sample Makefile which supports multiple build types in separate directories. The example illustrated shows debug and release builds.

Supports ...

• separate project directories for specific builds
• easy selection of a default target build
• silent prep target to create directories needed for building the project
• build-specific compiler configuration flags
• GNU Make's natural method of determining if project requires a rebuild
• pattern rules rather than the obsolete suffix rules

---

#
# Compiler flags
#
CC     = gcc
CFLAGS = -Wall -Werror -Wextra

#
# Project files
#
SRCS = file1.c file2.c file3.c file4.c
OBJS = $(SRCS:.c=.o)
EXE  = exefile

#
# Debug build settings
#
DBGDIR = debug
DBGEXE = $(DBGDIR)/$(EXE)
DBGOBJS = $(addprefix $(DBGDIR)/, $(OBJS))
DBGCFLAGS = -g -O0 -DDEBUG

#
# Release build settings
#
RELDIR = release
RELEXE = $(RELDIR)/$(EXE)
RELOBJS = $(addprefix $(RELDIR)/, $(OBJS))
RELCFLAGS = -O3 -DNDEBUG

.PHONY: all clean debug prep release remake

# Default build
all: prep release

#
# Debug rules
#
debug: $(DBGEXE)

$(DBGEXE): $(DBGOBJS)
    $(CC) $(CFLAGS) $(DBGCFLAGS) -o $(DBGEXE) $^

$(DBGDIR)/%.o: %.c
    $(CC) -c $(CFLAGS) $(DBGCFLAGS) -o $@ $<

#
# Release rules
#
release: $(RELEXE)

$(RELEXE): $(RELOBJS)
    $(CC) $(CFLAGS) $(RELCFLAGS) -o $(RELEXE) $^

$(RELDIR)/%.o: %.c
    $(CC) -c $(CFLAGS) $(RELCFLAGS) -o $@ $<

#
# Other rules
#
prep:
    @mkdir -p $(DBGDIR) $(RELDIR)

remake: clean all

clean:
    rm -f $(RELEXE) $(RELOBJS) $(DBGEXE) $(DBGOBJS)