[irods#7398] add find_dependency calls to a wrapper around our CMake …

…targets file

CMakeLists.txt

@@ -293,6 +293,7 @@ write_basic_package_version_file(
 install(
   FILES
   "${CMAKE_IRODS_BINARY_DIR}/IRODSConfigVersion.cmake"
+  "${CMAKE_CURRENT_SOURCE_DIR}/cmake/IRODSTargetsWrapper.cmake"
   DESTINATION "${CMAKE_INSTALL_LIBDIR}/irods/cmake"
   COMPONENT ${IRODS_PACKAGE_COMPONENT_DEVELOPMENT_NAME}
 )

cmake/IRODSConfig.cmake.not_yet_installed.in

@@ -2,7 +2,8 @@
 
 list(INSERT CMAKE_MODULE_PATH 0 "${CMAKE_CURRENT_LIST_DIR}/Modules")
 
-set_and_check(IRODS_TARGETS_PATH "${CMAKE_CURRENT_LIST_DIR}/IRODSTargets.cmake")
+set_and_check(IRODS_TARGETS_PATH "${CMAKE_CURRENT_LIST_DIR}/IRODSTargetsWrapper.cmake")
+set_and_check(IRODS_TARGETS_PATH_UNWRAPPED "${CMAKE_CURRENT_LIST_DIR}/IRODSTargets.cmake")
 
 if(NOT DEFINED IRODS_BUILD_WITH_CLANG)
   set(IRODS_BUILD_WITH_CLANG "@IRODS_BUILD_WITH_CLANG@")

cmake/IRODSTargetsWrapper.cmake

@@ -0,0 +1,27 @@
+# We can't define targets in our config file because the variables it defines
+# and the modules it adds to the search path need to be available before any
+# languages are enabled.
+# This is because we bundle a module to set the compilers to the clang we
+# provide via externals, and downstream projects which use this module must
+# include it before languages are enabled.
+# Therefore, we do not include our targets file in our CMake configuration
+# file, we have a wrapper for our targets file that pulls in our dependencies,
+# and we define a variable to make including our targets file
+# easy for downstream projects.
+# Yes, this is icky. We plan to move away from this model eventually.
+
+include(CMakeFindDependencyMacro)
+
+if (NOT DEFINED THREADS_PREFER_PTHREAD_FLAG)
+  set(THREADS_PREFER_PTHREAD_FLAG TRUE)
+endif()
+find_dependency(Threads)
+
+find_dependency(nlohmann_json "3.6.1")
+find_dependency(OpenSSL COMPONENTS Crypto SSL)
+find_dependency(fmt "8.1.1"
+  HINTS "${IRODS_EXTERNALS_FULLPATH_FMT}")
+find_dependency(spdlog "1.9.2"
+  HINTS "${IRODS_EXTERNALS_FULLPATH_SPDLOG}")
+
+include("${IRODS_TARGETS_PATH_UNWRAPPED}")