Get Target Include Directories using CMake

When working with CMake, it's common to set include directories for a target using target_include_directories or the older include_directories. But sometimes you need to retrieve those include directories later - for example, for debugging, logging, or passing them to another command. This tutorial explains how to get target include directories using CMake.

Let's say we have the following CMakeLists.txt file:

cmake_minimum_required(VERSION 3.27)
project(myapp)

set(CMAKE_CXX_STANDARD 17)

add_executable(${PROJECT_NAME} main.cpp)

include_directories(lib/include)
target_include_directories(${PROJECT_NAME} PRIVATE include)

get_target_property(TARGET_INCLUDES ${PROJECT_NAME} INCLUDE_DIRECTORIES)
message(STATUS "${TARGET_INCLUDES}")

We use get_target_property to query the INCLUDE_DIRECTORIES property of the target. This retrieves all include directories associated with the target, combining both global directories set with include_directories and target-specific directories set with target_include_directories.

Run the following command to generate the build files:

cmake -S . -B build

The command will print messages to the console. One of these messages will display the target's include directories. Example output:

-- /home/ubuntu/myproject/lib/include;/home/ubuntu/myproject/include

CMake returns a semicolon-separated list of absolute include directories for the given target.