Generic Makefile for c/cxx/asm and nix

Makefile

TARGET := a.out

CXX := g++
CC := gcc
AS := as
LD := $(CXX)

DEBUGFLAGS ?= -DDEBUG -ggdb -O0 -U_FORTIFY_SOURCE
RELEASEFLAGS ?= -DNDEBUG -O2

COMMONFLAGS ?= -flto -Wall -Wextra -pedantic -Werror=vla
CXXFLAGS ?= -std=c++17
CFLAGS ?= -std=c17
ASFLAGS ?=
LDFLAGS ?= -flto=auto

SRC_DIR := ./src
BUILD_DIR := ./build
BIN_DIR := ./bin

all: release
########################## DONT EDIT BELOW THIS LINE ##########################

.PHONY: all debug release clean compiledb run

SRCS := $(shell find $(SRC_DIR) -name *.c -or -name *.cpp -or -name *.s)
OBJS := $(SRCS:%=$(BUILD_DIR)/%.o)
DEPS := $(OBJS:.o=.d)

INC_DIRS := $(shell find $(SRC_DIR) -type d)
INC_DIRS_FLAGS := $(addprefix -I,$(INC_DIRS))

BUILD_SRC_DIRS := $(addprefix $(BUILD_DIR)/,$(SRC_DIR))

debug: CXXFLAGS += $(DEBUGFLAGS)
debug: CFLAGS   += $(DEBUGFLAGS)
debug: $(BIN_DIR)/$(TARGET)

release: CXXFLAGS += $(RELEASEFLAGS)
release: CFLAGS   += $(RELEASEFLAGS)
release: LDFLAGS  += -s
release: $(BIN_DIR)/$(TARGET)

# Target executable
$(BIN_DIR)/$(TARGET): $(OBJS) | $(BIN_DIR)
	$(LD) $(OBJS) -o $@ $(LDFLAGS)

# C object files
$(BUILD_DIR)/%.c.o: %.c | $(BUILD_SRC_DIRS)
	$(CC) $(CFLAGS) $(COMMONFLAGS) $(INC_DIRS_FLAGS) -c $< -o $@

# C++ object files
$(BUILD_DIR)/%.cpp.o: %.cpp | $(BUILD_SRC_DIRS)
	$(CXX) $(CXXFLAGS) $(COMMONFLAGS) $(INC_DIRS_FLAGS) -c $< -o $@

# Assembly object files
$(BUILD_DIR)/%.s.o: %.s | $(BUILD_SRC_DIRS)
	$(AS) $(ASFLAGS) -c $< -o $@

# C header depdency files
$(BUILD_DIR)/%.c.d: %.c | $(BUILD_SRC_DIRS)
	@$(CC) $(CFLAGS) $(COMMONFLAGS) $(INC_DIRS_FLAGS) $< -MM -MT $(@:%.c.d=%.c.o) >$@

# C++ header depdency files
$(BUILD_DIR)/%.cpp.d: %.cpp | $(BUILD_SRC_DIRS)
	@$(CXX) $(CXXFLAGS) $(COMMONFLAGS) $(INC_DIRS_FLAGS) $< -MM -MT $(@:%.cpp.d=%.cpp.o) >$@

# Directories
$(BUILD_DIR) $(BUILD_SRC_DIRS) $(BIN_DIR):
	@$(MKDIR_P) $@

compiledb: compile_commands.json

compile_commands.json: Makefile flake.nix shell.nix default.nix flake.lock
	bear -- make -B

clean:
	$(RM_R) $(BUILD_DIR) $(BIN_DIR)

-include $(DEPS)

MKDIR_P ?= mkdir -p
RM_R ?= rm -r

run: $(BIN_DIR)/$(TARGET)
	$(BIN_DIR)/$(TARGET)