Fix some TryEnum reference assists

[A4-Tacks]

• Fix convert_to_guarded_return
• Fix replace_let_with_if_let
• Fix replace_if_let_with_match

Example

fn foo() -> &'static Option<i32> { &None } fn main() { let x$0 = foo(); }

Before this PR

Assist not applicable

After this PR

fn foo() -> &'static Option<i32> { &None } fn main() { let Some(x) = foo() else { return }; }

---

fn main(action: Action) { $0let x = compute(); } fn compute() -> &'static Option<i32> { &None }

Before this PR

fn main(action: Action) { if let x = compute() { } } fn compute() -> &'static Option<i32> { &None }

After this PR

fn main(action: Action) { if let Some(x) = compute() { } } fn compute() -> &'static Option<i32> { &None }

---

fn foo(x: &Option<i32>) { $0if let Some(x) = x { println!("{}", x) } else { println!("none") } }

Before this PR

fn foo(x: &Option<i32>) { match x { Some(x) => println!("{}", x), _ => println!("none"), } }

After this PR

fn foo(x: &Option<i32>) { match x { Some(x) => println!("{}", x), None => println!("none"), } }

[ChayimFriedman2]

This could maybe benefit from a more structured approach to match ergonomics in IDE, but this is good enough as is IMO.

Thanks!

[ChayimFriedman2]

Actually, I think I prefer to put the strip_references() in TryEnum::from_ty().

[A4-Tacks]

Actually, I think I prefer to put the strip_references() in TryEnum::from_ty().

I'm not sure if it will damage crates/ide-assists/src/handlers/desugar_try_expr.rs

Can I extract a method like from_ty_without_strip()?

[ChayimFriedman2]

I actually think it's good even there. True, ? is not valid with references, but it can make life easier for people and can't hurt.