[renonce]

So the participant was in fact allowed to change the compiler command so `gcc` isn't even used...? I had wondered how gcc would compile an empty file.

[junon]

It was probably an oversight in the rules, as the entry's readme alludes to. They knew that by submitting this, the rules would be amended to be much more strict. Whether that includes requiring a compiler of some sort, I'm not sure. I doubt it - I would imagine the file just has to be 1 or more bytes now.

[ncmncm]

Gcc is perfectly happy to compile an empty file. But the linker does not find a "main" symbol in its output, so complains.