Function attribute to disallow unwrap of returned value

What it does

Sometimes you have a function where, if the caller unconditionally unwraps the returned value, there exists a better way to write that.

Advantage

• Encourages consistency.
• Encourages better panic error messages since you can write it once and re-use rather than re-writing `expect("shouldn't happen") N times.

Drawbacks

• People may be tempted to use the attribute for the wrong reason. It should not be used for "this is dangerous to unwrap" because that's rather subjective and that should be a decision left for the caller. Maybe there is a better attribute name?

Example

#[clippy::no_unwrap(reason = "use `get_foo` instead")]
fn try_get_foo() -> Option<Foo> {
  ...
}

fn get_foo() -> Option<Foo> {
  try_get_foo().expect("really nice error message")
}

fn example() {
  let x = try_get_foo().unwrap(); // LINT
}

Could be written as:

fn example() {
  let x = get_foo();
}

Comparison with existing lints

No response

Additional Context

One tricky question: should it also lint on usages of .expect("...")? I think this would usually be good, but I'm afraid it may cause some false positives where the caller intentionally uses a different error message. So I think I would not want it to lint expect.

Clippy should error/warn on using the attribute for a function that does not return Option or Result.

No source files, tests, or entry points are named in the issue. Start by resolving the attribute name, whether expect should be linted, and how invalid return types are diagnosed. Done means the attribute can warn on unwrap for Option or Result, recommend the alternate function, and reject unsupported return types.