linker input file unused because linking not done

Question

I have a problem when I compile my program, I have been trying some solutions on Questions but it doesnt work for me, so here is my problem

INCLUDE = include
LIB     = lib
OBJ     = obj
SRC     = src
BIN     = bin
CXX     = g++
CPPFLAGS = -Wall -g -c 

$(BIN)/pruebacronologia : $(OBJ)/pruebacronologia.o 
    $(CXX) -o $(BIN)/pruebacronologia $(OBJ)/EventoHistorico.o $(SRC)/EventoHistorico.cpp -I$(INCLUDE)
$(OBJ)/EventoHistorico.o : $(SRC)/EventoHistorico.cpp
    $(CXX) $(CPPFLAGS)  -o $(OBJ)/EventoHistorico.o $(SRC)/EventoHistorico.cpp -I$(INCLUDE)

$(OBJ)/cronologia.o : $(SRC)/cronologia.cpp $(OBJ)/EventoHistorico.o
    $(CXX) $(CPPFLAGS) -o $(OBJ)/cronologia.o $(SRC)/cronologia.cpp $(OBJ)/EventoHistorico.o -I$(INCLUDE)

$(OBJ)/pruebacronologia.o : $(SRC)/pruebacronologia.cpp $(OBJ)/cronologia.o 
    $(CXX) $(CPPFLAGS) -o $(OBJ)/pruebacronologia.o $(SRC)/pruebacronologia.cpp $(OBJ)/cronologia.o $(OBJ)/EventoHistorico.o -I$(INCLUDE)

Then i get this error on bash:

g++: warning: obj/cronologia.o: linker input file unused because linking not done
g++: warning: obj/EventoHistorico.o: linker input file unused because linking not done
g++ -o obj/EventoHistorico.o -Iinclude
g++: fatal error: no input files
compilation terminated.
make: *** [bin/pruebacronologia] Error 4

Stephen Kinger · Accepted Answer · 2016-10-29 11:53:39Z

1

Your makefile seems to be not well construct. For each target .o, just set a .o compiled from the corresponding .c file. To contruct the executable, just append all .o generated. I think something like this will work better :

INCLUDE = include
LIB     = lib
OBJ     = obj
SRC     = src
BIN     = bin
CXX     = g++
CPPFLAGS = -Wall -g -c 

$(BIN)/pruebacronologia : $(OBJ)/cronologia.o $(OBJ)/pruebacronologia.o $(OBJ)/EventoHistorico.o 
    $(CXX) -o $(BIN)/pruebacronologia $^ $(LDFLAGS)

$(OBJ)/EventoHistorico.o : $(SRC)/EventoHistorico.cpp
    $(CXX) $(CPPFLAGS)  -o $(OBJ)/EventoHistorico.o $(SRC)/EventoHistorico.cpp -I$(INCLUDE)

$(OBJ)/cronologia.o : $(SRC)/cronologia.cpp 
    $(CXX) $(CPPFLAGS) -o $(OBJ)/cronologia.o $(SRC)/cronologia.cpp -I$(INCLUDE)

$(OBJ)/pruebacronologia.o : $(SRC)/pruebacronologia.cpp  
    $(CXX) $(CPPFLAGS) -o $(OBJ)/pruebacronologia.o $(SRC)/pruebacronologia.cpp -I$(INCLUDE)

answered Oct 29, 2016 at 11:53

Stephen Kinger

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2 Comments

MadScientist Over a year ago

You have to add the -c option to the compiler when you want to generate object files. Otherwise it will try to link a program and fail.

Rusillo Over a year ago

Tanks, now Im getting some program errors, and still dont know why.

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