Which command displays function names during debug flow?

The command that displays function names during the debug flow is indeed "diagnose debug flow show function-name enable." This command specifically instructs the FortiGate device to output additional information about the functions being executed during the flow debug process. By enabling function name visibility, administrators can gain deeper insights into the execution flow of packets, allowing for more granular troubleshooting and analysis of network behavior.

Understanding the functions called during packet processing is critical for diagnosing issues, as it reveals how the FortiGate firewall is interpreting and handling traffic. This information can help in identifying potential configuration errors or performance bottlenecks.

The other options do not provide the same level of detail regarding function names during the debug flow. For instance, "show debug functions" may display general debug settings but doesn't specifically enable function name visibility in the flow. Similarly, "debug flow detail" gives more comprehensive information about the packet flow but lacks the specific focus on function names. Lastly, "diagnose debug functions enabled" does not exist as a commonly recognized command to enable function name display in debug flow. Thus, the correct answer helps administrators utilize the FortiGate debugging tools effectively for troubleshooting purposes.