ERROR “swiftc failed with exit code 1” when converting to latest syntax

Question

I was trying to convert syntax of old Swift project to new one as per few suggestion on Stack Overflow I tried converting it through Edit > Convert > To latest Synta

Answer 1

Cleaning the project wasn't working for me, this is because I didn't pay attention to the message right above (Xcode highlights only the final command).

In my case it was

:0: error: filename "FileDuplicated.swift" used twice: '/../filepath/FileDuplicated.swift' and '/../filepath/FileDuplicated.swift'
:0: note: filenames are used to distinguish private declarations with the same name
Command /../bin/swiftc failed with exit code 1

I had to change the name of one of the two files and it was solved.

Hope this can help someone, cheers