Invalid suggestion to introduce as_ref() for Option used in a place expression #99426
Description
Consider the following code
struct Foo {
val: i32
}
fn func1() {
let mut foo = Some(Foo{val: 0});
let ptr = &mut foo;
ptr.unwrap().val += 1;
}Here the diagnostic suggests to add as_ref as such:
note: this function takes ownership of the receiver `self`, which moves `*ptr`
help: consider calling `.as_ref()` to borrow the type's contents
|
8 | ptr.as_ref().unwrap().val += 1;
| +++++++++
This suggestion is incorrect – as_ref will never (AFAIK) produce a mutable reference necessary for the assignment. We should suggest as_mut where we know that a mutable reference will be required, instead.