Change jsoncpp discovery from CMake to pkg-config.

CMake is deprecated by upstream.

CMakeLists.txt

@@ -41,7 +41,8 @@ else()
   add_link_options("$<$<CONFIG:Debug>:${DEBUG_LDFLAGS}>")
 endif()
 
-find_package(jsoncpp CONFIG REQUIRED)
+find_package(PkgConfig REQUIRED)
+pkg_check_modules(jsoncpp REQUIRED IMPORTED_TARGET jsoncpp)
 # Some distributions do not contain Poco*Config.cmake recipes.
 find_package(Poco COMPONENTS Foundation Net NetSSL CONFIG)
 

src/CMakeLists.txt

@@ -11,7 +11,7 @@ target_include_directories(${PROJECT_NAME}
   PRIVATE "$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>")
 
 target_link_libraries(${PROJECT_NAME}
-  PRIVATE jsoncpp_lib)
+  PRIVATE PkgConfig::jsoncpp)
 
 # If no Poco*Config.cmake recipes are found, look for headers in standard dirs.
 if(PocoNetSSL_FOUND)

tests/CMakeLists.txt

@@ -9,7 +9,7 @@ target_include_directories(${PROJECT_NAME}_testlib
   "$<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/src>")
 
 target_link_libraries(${PROJECT_NAME}_testlib
-  PRIVATE Poco::Foundation Poco::Net Poco::NetSSL jsoncpp_lib)
+  PRIVATE Poco::Foundation Poco::Net Poco::NetSSL PkgConfig::jsoncpp)
 
 file(GLOB sources_tests test_*.cpp)