I'd expect the gdb output to be present in the task logs, as well as core dumps, unit test binaries, and debug symbols to be uploaded to S3. Note that latter three are present for sigaltstack_location_test, but that wasn't the C++ test running at the time of the timeout.

Some example cases:

• https://evergreen.mongodb.com/task/mongodb_mongo_master_suse12_run_unittests_1ff00ec66697eb16b6ae089681d9f3414f950fb1_21_04_29_01_28_45/0
• https://evergreen.mongodb.com/task/mongodb_mongo_master_enterprise_suse12_64_run_unittests_1ff00ec66697eb16b6ae089681d9f3414f950fb1_21_04_29_01_28_45/0
• https://evergreen.mongodb.com/task/mongodb_mongo_master_enterprise_ubuntu_sharding_task_executor_pool_rsm_matchPrimary_1804_64_bit_run_unittests_0cd377ed919b5a1ef95cbf9bbab22bc145cd4db4_21_04_19_06_01_27/3
• https://evergreen.mongodb.com/task/6054aa93d6d80a6e9e1fb91a_enterprise_rhel_80_64_bit_suggested_run_unittests_abf157fbf7f42b5d982d3d341f29883dae3f8c12_21_04_27_17_30_39/0