How do I add a library path in cmake?

c++, cmake

Solution

The simplest way of doing this would be to add

include_directories(${CMAKE_SOURCE_DIR}/inc)
link_directories(${CMAKE_SOURCE_DIR}/lib)

add_executable(foo ${FOO_SRCS})
target_link_libraries(foo bar) # libbar.so is found in ${CMAKE_SOURCE_DIR}/lib

The modern CMake version that doesn't add the `-I and -L` flags to every compiler invocation would be to use imported libraries:

add_library(bar SHARED IMPORTED) # or STATIC instead of SHARED
set_target_properties(bar PROPERTIES
  IMPORTED_LOCATION "${CMAKE_SOURCE_DIR}/lib/libbar.so"
  INTERFACE_INCLUDE_DIRECTORIES "${CMAKE_SOURCE_DIR}/include/libbar"
)

set(FOO_SRCS "foo.cpp")
add_executable(foo ${FOO_SRCS})
target_link_libraries(foo bar) # also adds the required include path

If setting the `INTERFACE_INCLUDE_DIRECTORIES` doesn't add the path, older versions of CMake also allow you to use `target_include_directories(bar PUBLIC /path/to/include)`. However, this no longer works with CMake 3.6 or newer.

Problem

I have 2 folders "inc" and "lib" in my project which have headers and static libs respectively. How do I tell cmake to use those 2 directories for include and linking respectively?

Original source