I am unable to figure out what is causing this error that I keep getting upon making my project:
i686-apple-darwin11-llvm-g++-4.2: -lncurses: linker input file unused because linking not done
And my make file looks like this:
CC = g++
LIB_FLAGS = -l ncurses
FLAGS = $(LIB_FLAGS)
DEPENDENCIES = window.o element.o
# FINAL OUTPUTS
main: main.cpp $(DEPENDENCIES)
$(CC) $(FLAGS) -o main.out main.cpp $(DEPENDENCIES)
# MODULES
window.o: main.h classes/window.cpp
$(CC) $(FLAGS) -c classes/window.cpp
element.o: main.h classes/element.cpp
$(CC) $(FLAGS) -c classes/element.cpp
# CLEAN
clean:
rm -rf *.o
rm main.out
Everything compiles okay, but I'm just curious what is causing this error message and what it means..
You are passing linker options to a compiler invocation together with -c, which means that linking is not performed and thereby -l options are unused. In your case, your LIB_FLAGS should not be in FLAGS, but instead specified in the the main: ... rule:
main: main.cpp
$(CC) $(FLAGS) $(LIB_FLAGS) ...
Do not give link flags when you compile (-c flag) your source files. Take a look for this example makefile (very similar as in makefile docs)
CPP = g++
CPPFLAGS =-Wall -g
OBJECTS = main.o net.o
PREFIX = /usr/local
.SUFFIXES: .cpp .o
.cpp.o:
$(CPP) $(CPPFLAGS) -c $<
.o:
$(CPP) $(CPPFLAGS) $^ -o $#
main: $(OBJECTS)
main.o: main.cpp
net.o: net.cpp net.h
.PHONY:
install: main
mkdir -p $(PREFIX)/bin
rm -f $(PREFIX)/bin/main
cp main $(PREFIX)/bin/main
clean:
rm -f *.o main
As has been mentioned already you're passing linker-related flags at the compile stage. Usually you want different flags for compiling and linking, e.g.
CC = g++
CPPFLAGS = -Wall -g -c -o $#
LDFLAGS = -l ncurses -o $#
DEPENDENCIES = main.o window.o element.o
# FINAL OUTPUTS
main: $(DEPENDENCIES)
$(CC) $(LDFLAGS) $(DEPENDENCIES)
# MODULES
main.o: main.h main.cpp
$(CC) $(CPPFLAGS) main.cpp
window.o: main.h classes/window.cpp
$(CC) $(CPPFLAGS) classes/window.cpp
element.o: main.h classes/element.cpp
$(CC) $(CPPFLAGS) classes/element.cpp
# CLEAN
clean:
-rm main $(DEPENDENCIES)
Related
Note: Unlike other Questions, this one is missing an obj file instead of a cpp file
I have a Directory called /Profiler
that got the following files:
Main.cpp
Draw.cpp
Draw.h (used in both cpp files)
Makefile
I created the following Makefile:
CC := g++
CCOPTS=-Wall -Wextra -O3 -std=c++17
Main_DEP_OBJ := Main.o Draw.o
Header:=Draw.h
all: main
%.o: %.C DEPS $(Header)
$(CC) ${CCOPTS} -c -o $# $<
Main: $(Main_DEP_OBJ)
${CC} ${CCOPTS} -o main $^
clean:
rm -f Main *.o
using the make command in Ubuntu gives me this error:
no rule to make target 'Main.o', needed by 'Main' . Stop.
You dont have a target rule for Main, or building .o file from the .cpp file.
CC := g++
CCOPTS=-Wall -Wextra -O3 -std=c++17
Main_DEP_OBJ := Main.o Draw.o
Header:=Draw.h
all: Main
%.o: %.cpp $(Header)
$(CC) ${CCOPTS} -c -o $# $<
Main: $(Main_DEP_OBJ)
${CC} ${CCOPTS} -o Main $^
clean:
rm -f Main *.o
I would like to make main-c to build main-c from main.c.
And make main-cpp to build main-cpp from main.cpp.
I have, all in the same folder:
main.c:
#include <stdio.h>
int main(int argc, char const *argv[]) {
printf("This ic C\n");
}
main.cpp:
#include <iostream>
int main(int argc, char const *argv[]) {
std::cout << "This is C++" << std::endl;
}
Makefile:
CFLAGS = -std=gnu11
CXXFLAGS = -std=gnu++11
CPPFLAGS = -g -Wall -O3
LDFLAGS =
LDLIBS =
OBJS = main.o
APP-C = main-c
APP-CPP = main-cpp
default:
echo "Check README.txt"
main-c: $(OBJS)
$(CC) $^ $(LDLIBS) -o $#
main-cpp: $(OBJS)
$(CXX) $^ $(LDLIBS) -o $#
clean:
-rm -Rf *.o
distclean: clean
-rm -Rf $(APP-C) $(APP-CPP)
So:
$ make main-c
cc -std=gnu11 -g -Wall -O3 -c -o main.o main.c
cc main.o -o main-c
But (also builds from .c):
$ make main-cpp
cc -std=gnu11 -g -Wall -O3 -c -o main.o main.c
c++ main.o -o main-cpp
I was expecting make main-cpp to use $(CXX) $^ $(LDLIBS) -o $# and build from .cpp. What am I missing?
I was expecting make main-cpp to use $(CXX) $^ $(LDLIBS) -o $# and build from .cpp.
It is. make main-cpp --debug will help you see what is going on.
The problem is you are relying on the default rule for making the main.o needed by both main-cpp and main-c target, but you want a different build when make-cpp target is invoked. In this case you'll need to define different non default rules to build the .o files. It's easiest if you just make make-cpp and main-c depend on a .o with a different name. Since they are different builds they should have different names anyway:
CFLAGS = -std=gnu11
CXXFLAGS = -std=gnu++11
CPPFLAGS = -g -Wall -O3
LDFLAGS =
LDLIBS =
APP-C = main-c
APP-CPP = main-cpp
default:
echo "Check README.txt"
main-c: %:%.o
$(CC) $^ $(LDLIBS) -o $#
main-cpp: %:%.o
$(CXX) $^ $(LDLIBS) -o $#
main-cpp.o: main.cpp
$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c $? -o $#
main-c.o: main.c
$(CC) $(CPPFLAGS) $(CFLAGS) -c $? -o $#
clean:
-rm -Rf *.o
distclean: clean
-rm -Rf $(APP-C) $(APP-CPP)
Both rules, main-c and main-cpp, require main.o to be created to complete, but you don't have a rule for creating main.o.
You're using make's implicit object file creation which is a built-in rule for creating a '.o' file from a source file. It can use either a '.c' or '.cpp/cc/C' file and will build using the appropriate variables. However, since you have both main.c and main.cpp, it looks like it defaults to using the C version.
You'd probably need to create explicit rules (and probably use different names) for each one.
I have a makefile for my program but I got everything recompiled every time I run it, even if I modify nothing.
Every time I run make it recompiles simHwIntf.cpp showHelp.cpp and sendFromFile.cpp
This is my make file:
IDIR = inc
LDIR = -L/usr/lib/x86_64-linux-gnu/
SDIR = src
ODIR = obj
BINDIR = bin
LDLIBS = -luhd
OBJ = $(patsubst %,$(ODIR)/%,$(O_FILES))
CC = g++
CFLAGS = -Wall -std=c++11 -I $(IDIR) #-Werror
BINARIES= main
C_FILES = simHwIntf.cpp showHelp.cpp sendFromFile.cpp
H_FILES = simHwIntf.h
O_FILES = $(C_FILES:.cpp=.o)
all: $(BINARIES)
#echo "Make file executed"
$(BINARIES): $(O_FILES)
$(CC) $(CFLAGS) -o $(BINDIR)/$# $(OBJ) $(LDIR) $(LDLIBS)
fileCreator: fileCreator.o
$(CC) $(CFLAGS) -o $(BINDIR)/$# $(ODIR)/fileCreator.o
fileHandler: fileHandler.o
$(CC) $(CFLAGS) -o $(BINDIR)/$# $(ODIR)/fileHandler.o
backYard: backYard.o
$(CC) $(CFLAGS) -o $(BINDIR)/$# $(ODIR)/backYard.o
%.o: $(SDIR)/%.cpp $(IDIR)/$(H_FILES)
$(CC) $(CFLAGS) -c -o $(ODIR)/$# $<
clean:
-rm -rf $(ODIR)/*.o *~
distclean: clean
-rm -rf $(BINDIR)/*
Each time the output in the shell is:
g++ -Wall -std=c++11 -I inc -c -o obj/simHwIntf.o src/simHwIntf.cpp
g++ -Wall -std=c++11 -I inc -c -o obj/showHelp.o src/showHelp.cpp
g++ -Wall -std=c++11 -I inc -c -o obj/sendFromFile.o src/sendFromFile.cpp
g++ -Wall -std=c++11 -I inc -o bin/main obj/simHwIntf.o obj/showHelp.o obj/sendFromFile.o -L/usr/lib/x86_64-linux-gnu/ -luhd
Make file executed
I've already search and read this: (How do I make Makefile to recompile only changed files?) but didn't help much.
Anybody that could give me a hand with this ?
I have a doubt with the directories, maybe one or several directories are re-created each time I run make and this causes everything inside to look like new to the compiler.
Thanks
You can see what triggered the build by echoing the dependencies that changed. Add this to your %.o target :
#echo [triggered by changes in $?]
You should also use the VPATH special variable instead of specifying the sources path in your %.o target. See GNU make VPATH documentation
Please try replacing
%.o: $(SDIR)/%.cpp $(IDIR)/$(H_FILES)
$(CC) $(CFLAGS) -c -o $(ODIR)/$# $<
with
$(ODIR)/%.o: $(SDIR)/%.cpp $(IDIR)/$(H_FILES)
$(CC) $(CFLAGS) -c -o $(ODIR)/$# $<
Directories matter when you define targets.
If a define a rule
myexec: objdir/myexec.o
$(CC) $(CFLAGS) -o bindir/myexec objdir/myexec.o $(LDFLAGS)
Make believes that that this would create the file myexec in the working directory. When you rerun make the target myexec wasn't found, so it will be created again. Add the paths in the targets and it should work.
Try replacing
BINARIES= main
with
BINARIES= $(BINDIR)/main
and the rule
$(CC) $(CFLAGS) -o $(BINDIR)/$# $(OBJ) $(LDIR) $(LDLIBS)
with
$(CC) $(CFLAGS) -o $# $^ $(LDIR) $(LDLIBS)
And change the other rules similarly.
Note, in general it is a bad idea to use $# in combination with a path when creating the target in some rule (as in $(BINDIR)/$#), because this will never create the actual target file. A bare $# should be sufficient.
I want my object files to be created in a subdirectory and not where Makefile lives. So, I saw this answer, which I couldn't apply to my case, so I tried this:
OBJS = main.o IO.o alloc.o communication.o
OBJSDIR = obj
SOURCE = main.cpp src/IO.cpp src/alloc.cpp src/communication.cpp
HEADER = headers/IO.h headers/alloc.h headers/communication.h
OUT = test
CXX = ../../mpich-install/bin/mpic++
CXXFLAGS = -I../../intel/mkl/include -Wl,--start-group -Wl,--end-group -lpthread -lm -ldl -Wall
LDFLAGS = ../../intel/mkl/lib/intel64/libmkl_scalapack_lp64.a -Wl,--start-group ../../intel/mkl/lib/intel64/libmkl_intel_lp64.a ../../intel/mkl/lib/intel64/libmkl_core.a ../../intel/mkl/lib/intel64/libmkl_sequential.a -Wl,--end-group ../../intel/mkl/lib/intel64/libmkl_blacs_intelmpi_lp64.a -lpthread -lm -ldl
all: $(OBJSDIR) $(OUT)
$(OBJSDIR):
mkdir $(OBJSDIR)
$(OUT): $(OBJS)
$(CXX) $(OBJS) -o $(OUT) $(CXXFLAGS) $(LDFLAGS)
# make -f Makefile clean
# create/compile the individual files >>separately<<
$(OBJSDIR)/main.o: main.cpp
$(CXX) -c main.cpp $(CXXFLAGS)
$(OBJSDIR)/IO.o: src/IO.cpp
$(CXX) -c src/IO.cpp $(CXXFLAGS)
$(OBJSDIR)/alloc.o: src/alloc.cpp
$(CXX) -c src/alloc.cpp $(CXXFLAGS)
$(OBJSDIR)/communication.o: src/communication.cpp
$(CXX) -c src/communication.cpp $(CXXFLAGS)
.PHONY: clean
clean:
rm -rf *.o
and I am getting:
gsamaras#pythagoras:~/konstantis/cholesky$ make
../../mpich-install/bin/mpic++ -I../../intel/mkl/include -Wl,--start-group -Wl,--end-group -lpthread -lm -ldl -Wall -c -o main.o main.cpp
make: *** No rule to make target 'IO.o', needed by 'test'. Stop.
I have a src folder, where all the .cpp files live (except from main.cpp, that lives in the same directory as the Makefile) and a headers directory, where all the header files live.
EDIT
I modified the first two lines, as such:
OBJSDIR = obj
OBJS = $(OBJSDIR)/main.o $(OBJSDIR)/IO.o $(OBJSDIR)/alloc.o $(OBJSDIR)/communication.o
and I am getting:
g++: error: obj/main.o: No such file or directory
...
The problem lies into the fact that the object files are still generated in the main directory!
You want to change the lines that invoke your compiler from:
$(OBJSDIR)/IO.o: src/IO.cpp
$(CXX) -c src/IO.cpp $(CXXFLAGS)
to:
$(OBJSDIR)/IO.o: src/IO.cpp
$(CXX) -c src/IO.cpp $(CXXFLAGS) -o $#
Note that $# is the automatic variable that corresponds to the target file being created. So in the above case it will be obj/IO.o. -o specifies the output filename.
Furthermore while it is unrelated to your question one of the nice things about placing all the build artifacts into a separate directory is cleaning is much easier:
clean:
rm -rf $(OBJSDIR) $(OUT)
Also, as a final note if you ever wish to do a parallel build you will have an issue as your object files rely on the build directory. There are a couple solutions to this including calling mkdir -p objs before every compiler invocation or setting up the directory as a dependency that is only built if it does not exist.
I have seen questions like these on SO but everyone has different answers and directory structures that aren't working for me.
My makefile:
CC = g++
DEBUG = -g -std=c++11
TARGET = main
OBJECT_FILES = BingResultSet.o main.o
INC_PATH = -I HTTPClientLib/include
LIB_PATH = -L HTTPClientLib/lib/
start: clean BingResultSet.o main.o
$(CC) $(DEBUG) $(INC_PATH) $(LIB_PATH) $(OBJECT_FILES) -o $(TARGET)
rm -f *.o
BingResultSet.o: BingResultSet.cpp BingResultSet.h
$(CC) $(DEBUG) $(INC_PATH) $(LIB_PATH) -c BingResultSet.cpp
main.o: main.cpp
$(CC) $(DEBUG) $(INC_PATH) $(LIB_PATH) -c main.cpp
clean:
rm -f $(OBJECT_FILES) $(TARGET)
My file structure:
/Desktop/DataMiner/.cpp, .h, and makefile
/Desktop/DataMiner/HTTPClientLib/include/HTTPClient.h
/Desktop/DataMiner/HTTPClientLib/lib/HTTPClient.a
What's the correct way to link my static lib in my makefile?
Here's my $0.02:
there was no static library involved. Assuming you meant the .o files
you mix dependencies and build rules, instead, avoid repeating build rules:
$(TARGET): $(OBJECT_FILES)
$(CXX) $(DEBUG) $(INC_PATH) $^ -o $# $(LIB_PATH)
%.o: %.cpp
$(CXX) $(DEBUG) $(INC_PATH) -c $< -o $#
You used CC for a C++ compiler. That's strange. Use CXX
You used LDFLAGS when you were just compiling
You hardcoded the source and destination paths. Instead use the automatic variables ($^, $< for source; $# for destination)
You tried to hardcode header dependencies. That's error-prone and messes up source specification (you don't want $^ to list .h files in your command line...). Instead, use gcc -MM¹ to generate the dependencies for you!
Next, do a conditional include of those dependencies:
.depends:
$(CXX) -MM $(CXXFLAGS) -c *.cpp > $#
-include .depends
It's usually handy to keep the .o files so you can speed up builds. Of course, this was not a good plan until you generated the header dependencies automatically. If you insist, you can comment the .PRECIOUS target. Intermediate targets are automatically deleted by GNU Make
Here's the integrated offering I ended up with:
CXX = g++
TARGET = main
OBJECT_FILES = BingResultSet.o main.o
INC_PATH = -I HTTPClientLib/include
LIB_PATH = -L HTTPClientLib/lib/
CPPFLAGS = -g -std=c++11
CPPFLAGS+= $(INC_PATH)
# standard derived flags:
CXXFLAGS+=$(CPPFLAGS)
LDFLAGS+=$(LIB_PATH)
start: .depends $(TARGET)
$(TARGET): $(OBJECT_FILES)
$(CXX) $(CXXFLAGS) $^ -o $# $(LDFLAGS)
%.o: %.cpp
$(CXX) $(CXXFLAGS) -c $< -o $#
clean:
rm -f .depends $(OBJECT_FILES) $(TARGET)
# to keep the .o files:
.PRECIOUS: $(OBJECT_FILES)
.depends:
$(CXX) -MM $(CXXFLAGS) -c *.cpp > $#
-include .depends
On a very simple sample set of files you get:
$ make clean
rm -f .depends BingResultSet.o main.o main
$ make
g++ -MM -g -std=c++11 -I HTTPClientLib/include -c *.cpp > .depends
g++ -I HTTPClientLib/include -c BingResultSet.cpp -o BingResultSet.o
g++ -I HTTPClientLib/include -c main.cpp -o main.o
g++ -I HTTPClientLib/include BingResultSet.o main.o -o main -L HTTPClientLib/lib/
$ cat .depends
BingResultSet.o: BingResultSet.cpp BingResultSet.h
main.o: main.cpp BingResultSet.h
test.o: test.cpp
¹ (or similar, see man-page)