Follow up to this example: let's say that I don't know the answer, what do I search for if I want to find out?
The only thing that keeps this from being as big an issue as it ought to be is that rustc’s error output is really, really good. Usually it tells you how to fix it.
The second part of your question is bad syntax however, I agree (but still, 90% of the unscrutability of rust is caused by its concepts imho).
That depends on what you want. Do you want the address to a mutable Option of a Thing, or do you want an Option of an address of a mutable Thing? The mental model you have of your code should make this rather clear.
It's a complex language with unique properties, and it's syntax was carefully crafted towards it's goals - high performance, close to hardware, no runtime, memory safety etc.
'?' doesn't mean anything like what it means in every other programming language, and it's everywhere. It is so frequently used that you get used to it pretty quick, but it is very not obvious to a beginner.
Obscure #[blah(blah)] attributes attached to nearly every line of code in some places. Do those have meaning? Are they just hints to the compiler? You'd better hit the docs to find out.
Do I need a &mut Option<Thing>, or an Option<&mut Thing>? And how do I get that out, as a `opt.as_ref().mut()`, `opt.as_ref_mut()`, or &mut *opt`? Are these valid? What's the difference? Idk, it's inscrutable.
Rust syntax really, really sucks my friend.