problem in adding libraries during linking process in Makefile - c++

Question

I am new to Makefiles. I am using opencv and lpthread libraries in a project. The following makefile code dont seems to work. It seems the linking process is failing. Please point out the mistake I made here.
OS: Ubuntu 18.04
CC=g++
LIBS=`pkg-config --cflags --libs opencv`
CXXFLAGS= -c -Wall -std=c++17 -lpthread -march=native -mtune=native -O2
CXXFLAGS2= -Wall -std=c++17 -lpthread -march=native -mtune=native -O2
all: a.out
a.out: main.o brain_starter.o brain_class.o segment_class.o \
logic_core.o data_package_class.o core_class.o
$(CC) $(CXXFLAGS2) $(LIBS) -o a.out main.o brain_starter.o brain_class.o \
segment_class.o logic_core.o data_package_class.o core_class.o
main.o: main.cpp dependency_functions.h
$(CC) $(CXXFLAGS) main.cpp
brain_starter.o: brain_starter.cpp
$(CC) $(CXXFLAGS) brain_starter.cpp
brain_class.o: brain_class.cpp
$(CC) $(CXXFLAGS) brain_class.cpp
segment_class.o: segment_class.cpp
$(CC) $(CXXFLAGS) segment_class.cpp
logic_class.o: logic_class.cpp
$(CC) $(CXXFLAGS) logic_class.cpp
data_package_class.o: data_package_class.cpp
$(CC) $(CXXFLAGS) $(LIBS) data_package_class.cpp
core_class.o: core_class.cpp
$(CC) $(CXXFLAGS) core_class.cpp
clean:
rm -rf *o a.out

Answer 1

I rearranged libs in the linking code and the makefile worked. Here is the working code.
CC=g++
OPENCVLIBS=`pkg-config --cflags --libs opencv`
LIBS= -lpthread
CXXFLAGS= -c -Wall -std=c++17 -march=native -mtune=native -O2
CXXFLAGS2= -Wall -std=c++17 -lpthread -march=native -mtune=native -O2
all: a.out
a.out: main.o brain_starter.o brain_class.o segment_class.o \
logic_core.o data_package_class.o core_class.o
$(CC) $(CXXFLAGS2) -o a.out main.o brain_starter.o brain_class.o segment_class.o logic_core.o data_package_class.o core_class.o $(LIBS) $(OPENCVLIBS)
main.o: main.cpp dependency_functions.h
$(CC) $(CXXFLAGS) $(LIBS) main.cpp
brain_starter.o: brain_starter.cpp
$(CC) $(CXXFLAGS) $(LIBS) brain_starter.cpp
brain_class.o: brain_class.cpp
$(CC) $(CXXFLAGS) $(LIBS) brain_class.cpp
segment_class.o: segment_class.cpp
$(CC) $(CXXFLAGS) $(LIBS) segment_class.cpp
logic_class.o: logic_class.cpp
$(CC) $(CXXFLAGS) $(LIBS) logic_class.cpp
data_package_class.o: data_package_class.cpp
$(CC) $(CXXFLAGS) $(LIBS) $(OPENCVLIBS) data_package_class.cpp
core_class.o: core_class.cpp
$(CC) $(CXXFLAGS) core_class.cpp
clean:
rm -rf *o a.out