CMake: Attempted to add link library to target which is not built in this directory

Question

I'm having a an issue compiling some unit tests in my cmake project. The idea is to add these boost unit tests as executables, so that I can then run them. Anyway I'm getting this error that I don't quit understand, which is saying that I cannot link my cpp unit tests which must be linked to test the library I built. The two unit tests I'm trying to link and add as executables are, DownloadTickers.cpp and GetTickersForLetter.cpp.

My directory structure is as follows:

> Algo
  > build (this is where I do: cmake .. which gives me errors)
  -CMakeLists.txt (top level cmake)
  -algo.h.ini
  -run.cpp
  > NetworkModule
   > CrawlTickers
    -CMakeLists.txt
    -CrawlTickers.cpp
    -CrawlTickers.hpp
    > tests
     -CMakeLists.txt
     -DownloadTickers.cpp
     -GetTickersForLetter.cpp

The CMakeLists.txt for Algo is:

cmake_minimum_required (VERSION 2.8)
project (Algo)

set (Algo_VERSION_MAJOR 0)
set (Algo_VERSION_MINOR 1)
set (CMAKE_CXX_COMPILER g++-4.8)
set (CMAKE_BUILD_TYPE Release)

add_definitions(
  -std=c++11
)

configure_file(
  "${PROJECT_SOURCE_DIR}/algo.h.in"
  "${PROJECT_BINARY_DIR}/algo.h"
)

include_directories("${PROJECT_BINARY_DIR}")

add_subdirectory(NetworkModule/CrawlTickers)

add_executable(Run run.cpp)

The CMakeLists.txt for CrawlTickers is:

find_package(Boost COMPONENTS system filesystem unit_test_framework REQUIRED)

add_library(CrawlTickers SHARED CrawlTickers.cpp)

add_subdirectory(tests)

target_link_libraries(
  CrawlTickers
  cpprest
)

target_link_libraries(
  DownloadTickers
  CrawlTickers
  ${Boost_FILESYSTEM_LIBRARY}
  ${Boost_SYSTEM_LIBRARY}
  ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY}
)

target_link_libraries(
  GetTickersForLetter
  CrawlTickers
  ${Boost_FILESYSTEM_LIBRARY}
  ${Boost_SYSTEM_LIBRARY}
  ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY}
)

The CMakeLists.txt for tests is:

add_executable( DownloadTickers DownloadTickers.cpp )

add_executable( GetTickersForLetter GetTickersForLetter.cpp )

My thinking is that cmake would naturally register DownloadTickers and GetTickersForLetter as executables in the CrawlTickers CMakeLists.txt and then know how to link it to the target, but I have no idea why I'm getting this error. Any help is greatly appreciated. Thanks.

Answer 1

The target_link_libraries directive needs to be part of the same CMakeLists.txt as the add_executable directive. This also applies to libraries. Think of each directory and associated CMakeLists.txt as a subproject.

As pointed out in the comments, CMake 3.13 now allows the requested behavior.