CMake and Gcov

While trying to use Gcov for my project I noticed that it doesn’t work well together with CMake. The problem is that CMake generates files named file.cpp.gcno while gcov searches for file.gcno. Luckily, there is an easy solution.

First things first, in order to use Gcov in CMake you have to pass some flags to g++ so something similar to the following should be in your CMakeLists.txt

set(CMAKE_CXX_FLAGS "-g -O0 -Wall -fprofile-arcs -ftest-coverage")

This would cause the *.cpp.gcno files to be generated next to your object files. Assuming your cpp files were inside a src subdirectory, you will find these files in a folder like build/src/CMakeFiles/project_name.dir.

But we didn’t want this *.cpp.gcno extension, so the solution is to also add the following line in your CMakeLists.txt


That’s it! By adding that one line your files will just have the *.gcno extension.

Now we can run our tests. After running the tests you can run gcov in the folder where you want to create your *.gcov files. The code below is meant to be executed in a new empty subdirectory inside your build folder and assumes that your source files were in a src directory.

gcov ../../src/*.cpp --object-directory ../src/CMakeFiles/project_name.dir/