Separate CUB's catch2 test binaries by default for CI. (#1482)

* Build/run all catch2 tests separated to debug timeouts.

* Trivial change to common catch2 header to trigger uncached rebuild.

* Move the Catch2 main TUs into an object library for separated test builds.

CMakePresets.json

@@ -164,6 +164,7 @@
         "CCCL_ENABLE_CUB": true,
         "CUB_ENABLE_TESTING": true,
         "CUB_ENABLE_EXAMPLES": true,
+        "CUB_SEPARATE_CATCH2": true,
         "CUB_ENABLE_DIALECT_CPP11": false,
         "CUB_ENABLE_DIALECT_CPP14": false,
         "CUB_ENABLE_DIALECT_CPP17": false,

cub/test/CMakeLists.txt

@@ -200,8 +200,14 @@ function(cub_add_test target_name_var test_name test_src cub_target launcher_id)
     endif() # config_c2h_target
 
     if (CUB_SEPARATE_CATCH2)
+      set(catch2_main_objects ${config_prefix}.catch2_main_objects)
+      if (NOT TARGET ${catch2_main_objects})
+        add_library(${catch2_main_objects} OBJECT catch2_runner.cpp catch2_runner_helper.cu)
+        target_link_libraries(${catch2_main_objects} PUBLIC Catch2::Catch2)
+      endif()
+
       add_executable(${test_target} "${test_src}")
-      target_compile_definitions(${test_target} PRIVATE "CUB_CONFIG_MAIN")
+      target_link_libraries(${test_target} PRIVATE ${catch2_main_objects})
       add_dependencies(${config_meta_target} ${test_target})
 
       add_test(NAME ${test_target} COMMAND "$<TARGET_FILE:${test_target}>")

cub/test/catch2_test_helper.h

@@ -90,8 +90,8 @@ namespace detail
   template <class T>
   std::vector<T> to_vec(c2h::device_vector<T> const& vec)
   {
-    c2h::host_vector<T> tmp = vec;
-    return std::vector<T>{tmp.begin(), tmp.end()};
+    c2h::host_vector<T> temp = vec;
+    return std::vector<T>{temp.begin(), temp.end()};
   }
 
   template <class T>