I can't compile google test which telling linker input unused (macOS)

Question

I have downloaded the google test with below command.

wget https://github.com/google/googletest/archive/release-1.8.0.zip

and I run the following command to install the libraries to my macOS 10.13.5

unzip release-1.8.0.zip cd googletest-release-1.8.0 mkdir build cd build cmake .. make sudo make install

and i try to compile the test as below code with command g++ -c -std=c++11 -stdlib=libc++ -lgtest -lgtest_main -pthread -o cpptest test.cpp.

#include <iostream>
#include <gtest/gtest.h>

TEST(firstTest, abs)
{
   EXPECT_EQ(1, abs( -1 ));
   EXPECT_EQ(1, abs( 1 ));
}

int main(int argc, char **argv) {
     std::cout << "Running main() from testmain.cc\n";

     testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
 }

but i get below warnings

clang: warning: -lgtest: 'linker' input unused [-Wunused-command-lin-argument]
clang: warning: -lgtest_main: 'linker' input unused [-Wunused-command-line-argument]

Does anyone can fix this problems?

Answer 1

g++ -c is used to compile a source file to an object file. This stage does not link an executable, i.e. it does not use linker, thus linker flags -lgtest -lgtest_main are not used. If you want to compile an executable the proper compand will be without -c:

g++ -std=c++11 -lgtest -lgtest_main -pthread -o cpptest test.cpp

Note, I have removed not required use of -stdlib.