Say that division by zero for primitive types panics

[mattheww]

Closes #1375

Explicitly say that division by zero for primitive types panics (for both / and %).

[ehuss]

Thanks!

Just a random thought is that const-eval works differently (it is a compile-time error, though I'm not sure if that is always the case), so that would need to be documented differently, though I'm not sure how.

[mattheww]

Treat that as part of #579?

[ehuss]

I was roughly thinking that it could go into const-eval chapter, though I guess it already discusses this ("Behaviors such as out of bounds array indexing or overflow are compiler errors"). There's probably more rigor that could be applied to the const-eval chapter to exhaustively cover its specific behavior, but I think for now it is probably sufficient.

[JanBeh]

Not all primitive type panic on division by zero.

fn main() {
    println!("{}", 1.0 / 0.0);
}

This gives infinity. (Playground)