Once upon a time, Oracle used Intel C Compiler (ICC) to compile Oracle RDBMS on some platforms [1].
I don't know if Oracle is still using ICC for that or not. (If you download Oracle RDBMS, and check the binaries, you will be able to work it out. I can't be bothered.)
There can be various traces left in strings, the symbol table, etc
Many compilers statically link implementations of various built-in functions into the resulting executable, and that can result in different symbol table entries
I don't know if Oracle is still using ICC for that or not. (If you download Oracle RDBMS, and check the binaries, you will be able to work it out. I can't be bothered.)
[1] https://www.businesswire.com/news/home/20030507005238/en/Ora...