CODEWITHSUNDEEP
makefile
Hyunan Kwon
Hyunan Kwon

Reputation: 575

Makefile compile twice

I run make with this makefile on main.cpp which does nothing.

CXX = g++
CXXFLAGS = -g -std=c++11 -stdlib=libc++ -Wall

SRCDIR = .
TARGET = tfm

SRCS = $(SRCDIR)/main.cpp
OBJS = $(SRCS:.cpp=.o)

all: $(TARGET)
$(TARGET): $(OBJS)
    $(CXX) $(CXXFLAGS) -o $@ $^

clean:
    $(RM) $(TARGET) $(OBJS)

And, compile was done twice.

g++ -g -std=c++11 -stdlib=libc++ -Wall   -c -o main.o main.cpp
g++ -g -std=c++11 -stdlib=libc++ -Wall -o tfm main.o

Why is this happening?

Upvotes: 0

Views: 378

Answers (2)

Jens
Jens

Reputation: 72756

And, compile was done twice.

No, it wasn't. The first line shows the compilation of main.cpp into main.o (which gets triggered by a built-in make rule for how to turn *.cpp into *.o). The second shows the link step, linking main.o with libraries to result in the executable tfm.

In other words, everything is swimmingly beautiful.

Upvotes: 2

ceving
ceving

Reputation: 23871

Running make on the source code does not make much sense. You have to tell make what you want to generate. And you do not want to generate the source.

Complation is not done twice. The first line compiles the the second line links.

Upvotes: 0

Related Questions