Who? When?

Writing bugs in Rust is trivial and happens all the time. "do_stuff(sysv[1], sysv[2])" is a bug if you reversed the sysv arguments by accident. You can easily create a more complex version of that with a few "if" conditionals and interaction with other flags.

There are many such silly things people can – and do – trivially get wrong all the time. Most bugs I've written are of the "I'm a bloody idiot"-type. The only way to have a fool-proof compiler is to know intent.

What people may say is something like "if it compiles, then it runs", which is generally true, but doesn't mean it does the right thing (i.e. is free of bugs).