How to reuse cmake install for package() method

It is possible that your project’s CMakeLists.txt has already defined some functionality that extracts the artifacts (headers, libraries, binaries) from the build and source folder to a predetermined place and does the post-processing (e.g., strips rpaths). For example, one common practice is to use CMake install directive to that end.

When using Conan, the install phase of CMake is wrapped in the package() method.

The following excerpt shows how to build and package with CMake within Conan. Mind that you need to configure CMake both in build() and in package() since these methods are called independently.

def configure_cmake(self):
    cmake = CMake(self)
    cmake.definitions["SOME_DEFINITION"] = True

    return cmake

def build(self):
    cmake = self.configure_cmake()

def package(self):
    cmake = self.configure_cmake()

def package_info(self):
    self.cpp_info.libs = ["libname"]

The package_info() method specifies the list of the necessary libraries, defines and flags for different build configurations for the consumers of the package. This is necessary as there is no possible way to extract this information from the CMake install automatically.


Please mind that if you use cmake.install() in package(), it will be called twice if you are using no_copy_source attribute in your conanfile.

CMake usually uses install directive to package both the artifacts and source code (i.e. header files) into the package folder. Hence calling package() twice, while having no side effects, is wasting a couple of cycles, since source code is already copied in the first invocation of package() and the install step will be done twice. Files will be simply overwritten, but install steps are sometimes time-expensive and this doubles the “packaging” time.

This might be unintuitive if you only use CMake, but mind that Conan needs to cater to many different build systems and scenarios (e.g. where you don’t control the CMake configuration directly) and hence this workflow is indispensable.