simpler makefile

Makefile

# MIT License
# 
# Copyright (c) 2023 Matthew Elmer
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# GNU Make notes:
# -MD: Generate dependency output file as side effect of compilation process
# -MMD: Same as MD but only mention user header files
# -MP: Makes make not freak out when you remove a header w/o updating makefile
# -MT: Change the target of the rule emitted by dependency generation
# $@: target
# $^: all prerequisites
# $<: first prerequisite
# vpath not used because it doesn't work with automatic source file discovery
# target: prerequisites | order-only prerequisites

# export MAKEFLAGS = -j1  # For single-threaded compilation

# Name directories
SRC_DIR := src
BUILD_DIR := build
OBJ_DIR := ${BUILD_DIR}/obj
DEP_DIR := ${BUILD_DIR}/dep
CPPCHECK_DIR := ${BUILD_DIR}/cppcheck
BUILD_DIRS := ${BUILD_DIR} ${OBJ_DIR} ${DEP_DIR} ${CPPCHECK_DIR}

# Name executable
BIN := ${BUILD_DIR}/executable_name

# List directories where header files are found
_INCLUDE := include
INCLUDE := ${_INCLUDE:%=-I%}

# Make obj and dep files per source file
SRC := $(wildcard ${SRC_DIR}/*.cc)  # Sneaky trick to get all .cc in a directory
OBJ := ${SRC:${SRC_DIR}/%.cc=${OBJ_DIR}/%.o}
DEP := ${OBJ:${OBJ_DIR}/%.o=${DEP_DIR}/%.d}

# Compiler, preprocessor, and linker setup
STD := c++11
CXX := g++
CXXFLAGS := -Wall -Wextra -Wshadow -std=${STD}
CPPFLAGS = -MP -MMD -MT $@ -MF ${DEP_DIR}/$*.d  # Note: uses = instead of :=
LDFLAGS :=

# Debug configuration
CXXFLAGS += -g

# Release configuration
# CXXFLAGS += -O3
# CPPFLAGS += -DRELEASE -DNDEBUG

# If "make" or "make all" is called, output info. Check and make the executable.
.PHONY: all
all: ${BIN}

.PHONY: memcheck
memcheck: all
	valgrind --leak-check=yes ${BIN} ${ARGS}

# If "make run" is called, make the executable and run it
.PHONY: run
run: all
	${BIN} ${ARGS}

# Delete all object files, all dep files, and the executable
.PHONY: clean
clean:
	rm -rf ${BUILD_DIR}

# Link the object files to build the executable
${BIN}: ${OBJ}  # Note: You can call this recipe directly!
	${CXX} ${LDFLAGS} $^ -o $@

# Compile the source files into object files
${OBJ}: ${OBJ_DIR}/%.o: ${SRC_DIR}/%.cc | ${BUILD_DIRS}
	cppcheck --enable=warning --cppcheck-build-dir=${CPPCHECK_DIR} --std=${STD} --quiet --error-exitcode=1 $<
	${CXX} ${CXXFLAGS} ${CPPFLAGS} ${INCLUDE} -c $< -o $@

# Create the required directories if they don't already exist
${BUILD_DIRS}:
	mkdir -p $@

# The dash makes make not fail if .d file not found
-include ${DEP}