c++ - 使用 Makefile 创建两个输出

Question

我想创建一个 makefile，它在 C++ 中运行一次程序，一次使用“CXXFLAGS = -std=c++11 -g -O3 -DTEST -fopenmp”，一次使用:“CXXFLAGS = -std=c++11 -g -O3 -fopenmp"最后输出两个不同的文件，如 P1-Test 和 P1。我该如何编辑这个文件？

CXX = g++
CXXFLAGS = -std=c++11 -g -O3 -fopenmp

ifdef code_coverage
    GCOV_FLAG :=  -DTEST
else
    GCOV_FLAG :=
endif

all: P1
        @echo The program has been compiled

# implicit rule: create x from x.cpp
.cpp:
        $(CXX) $(CXXFLAGS) $? -o $@
        $(CXX) $(CXXFLAGS) $(GCOV_FLAG) $? -o $@
.PHONY: clean
clean:
        $(RM) -r P1 *.dSYM

Answer 1

我的建议:

CXX = g++
CXXFLAGS = -std=c++11 -g -O3 -fopenmp

all: P1 P1-Test
    @echo The program has been compiled

# implicit rule: create x from x.cpp
.cpp:
    $(CXX) $(CXXFLAGS) $? -o $@

.PHONY: clean
clean:
    $(RM) -r P1 *.dSYM

P1: main.o second.o
    $(CXX) $(CXXFLAGS) $(LDFLAGS) -o "$@" $^

P1-Test: CXXFLAGS+=-DTEST
P1-Test: main.o second.o
    $(CXX) $(CXXFLAGS) $(LDFLAGS) -o "$@" $^

带有示例源:

• 文件 main.cpp

   extern void foo(); // should be in second.h or something
  
   int main() { foo(); }
  

• 文件 second.cpp

   #include <cstdio>
  
   void foo() {
   #ifdef TEST
       puts("TEST defined");
   #else
       puts("TEST not defined");
   #endif
   }
  

结果

$ make -B
g++ -std=c++11 -g -O3 -fopenmp -o "P1" main.cpp second.cpp 
g++ -std=c++11 -g -O3 -fopenmp -DTEST -o "P1-Test" main.cpp second.cpp 
The program has been compiled

当然还有输出:

./P1; ./P1-Test 
TEST not defined
TEST defined

备选

如果您的 .o 文件确实是 .PRECIOUS，您可能想要构建单独的拷贝。这里我拆分成release/main.o和test/main.o:

CXX = g++
CXXFLAGS = -std=c++11 -g -O3 -fopenmp

all: P1 P1-Test
    @echo The program has been compiled

test/%.o: CXXFLAGS+=-DTEST
test/%.o: %.cpp
    mkdir -pv $(@D)
    $(CXX) $(CXXFLAGS) $? -c -o $@

release/%.o: %.cpp
    mkdir -pv $(@D)
    $(CXX) $(CXXFLAGS) $? -c -o $@

.PHONY: clean
clean:
    $(RM) -rfv P1 P1-Test *.dSYM release/ test/

P1: release/main.o release/second.o
P1-Test: test/main.o test/second.o

P1 P1-Test:
    $(CXX) $(CXXFLAGS) -o "$@" $^ $(LDFLAGS)

给出:

mkdir -pv release
g++ -std=c++11 -g -O3 -fopenmp main.cpp -c -o release/main.o
mkdir -pv release
g++ -std=c++11 -g -O3 -fopenmp second.cpp -c -o release/second.o
g++ -std=c++11 -g -O3 -fopenmp -o "P1" release/main.o release/second.o 
mkdir -pv test
g++ -std=c++11 -g -O3 -fopenmp -DTEST main.cpp -c -o test/main.o
mkdir -pv test
g++ -std=c++11 -g -O3 -fopenmp -DTEST second.cpp -c -o test/second.o
g++ -std=c++11 -g -O3 -fopenmp -o "P1-Test" test/main.o test/second.o 
echo The program has been compiled