Question

Following makefile:

#Regular c++ rules
CXX=g++
CXXFLAGS=-Wall -march=native -ffast-math -O3
CXX_OBJECTS=AbsNode.o rle16.o rle8.o

# Link command:
test : $(CXX_OBJECTS)
    $(CXX) $(CXX_OBJECTS) -o test

# Compilation commands: 
$.o : %.cpp
    $(CXX) -c $< $(CXXFLAGS) -o $@

Outputs

g++ -Wall -march=native -ffast-math -O3 -c -o AbsNode.o AbsNode.cpp
g++ -Wall -march=native -ffast-math -O3 -c -o rle16.o rle16.cpp
g++ -Wall -march=native -ffast-math -O3 -c -o rle8.o rle8.cpp

while I expect

g++ -c AbsNode.cpp -Wall -march=native -ffast-math -O3  -o AbsNode.o 
g++ -c rle16.cpp -Wall -march=native -ffast-math -O3 -o rle16.o 
g++ -c rle8.cpp -Wall -march=native -ffast-math -O3 -o rle8.o 

Why is the order of arguments to g++ switched compared to the rule stated in makefile???

Answer 1

$.o : %.cpp

You typed $ instead of %, which turned is into a non-template rule. However make has a default rule for C++ file, which was taken instead of yours. The order of arguments match this internal rule.