A drop-in makefile for lazy C++ programmers

makefile

# disable default implicit rules
MAKEFLAGS += --no-builtin-rules
.SUFFIXES:

# project name
PROJECT  = myproject

# common compiler/linker flags
CXX      = g++
CXXFLAGS = -std=c++11 -Wall -Wextra -Wpedantic
LDFLAGS  =
DEFINES  =

# build specific compiler/linker flags
BUILD ?= release
ifeq ($(BUILD), debug)
  CXXFLAGS += -Og -g
  DEFINES  += -DVERBOSE=1
else ifeq ($(BUILD), profile)
  CXXFLAGS += -march=native -O3 -g
  DEFINES  += -DNDEBUG
else ifeq ($(BUILD), release)
  CXXFLAGS += -march=native -O3 -flto
  LDFLAGS  += -fuse-linker-plugin -s
  DEFINES  += -DNDEBUG
else
  $(error unrecognized BUILD)
endif
BUILDDIR = bin.$(BUILD)

# find the hash of the git commit we are building from
GIT_HASH  = $(shell git rev-parse --short HEAD 2> /dev/null || echo *unknown*)
DEFINES  += -DGIT_HASH=\"$(GIT_HASH)\"

# generate lists of object files (all and existing only)
OBJECTS_ALL = $(addprefix $(BUILDDIR)/,$(patsubst %.cpp,%.o,$(wildcard *.cpp)))
OBJECTS_EXT = $(wildcard $(BUILDDIR)/*.o)

# define implicit rule to compile a cpp file
$(BUILDDIR)/%.o : %.cpp | $(BUILDDIR)
	$(CXX) $(CXXFLAGS) $(DEFINES) -c $< -o $@
	$(CXX) $(CXXFLAGS) $(DEFINES) -MM $< -MT $@ > $(BUILDDIR)/$*.dep

# main executable
$(BUILDDIR)/$(PROJECT) : $(OBJECTS_ALL) | $(BUILDDIR)
	$(CXX) $(CXXFLAGS) $^ $(LDFLAGS) -o $@

# build directory creation
$(BUILDDIR) :
	mkdir $(BUILDDIR)

# pull in dependency info for existing object files
-include $(OBJECTS_EXT:.o=.dep)

# obligatory clean target
clean :
	rm -rf bin.*/