let-chain with missing `let` in the middle causes multiple errors

[estebank]

Edit: only remaining case is eliminating the first error in

fn main() {
    let x = Some(42);
    if Some(_) = x
        && let Some(x) = x
    {}
}

error: expected expression, found `let` statement
 --> src/main.rs:4:12
  |
4 |         && let Some(x) = x
  |            ^^^
  |
  = note: only supported directly in conditions of `if` and `while` expressions

error: let-chain with missing `let`
 --> src/main.rs:3:8
  |
3 |     if Some(_) = x
  |        ^^^^^^^----
  |        |
  |        expected `let` expression, found assignment
4 |         && let Some(x) = x
  |            --------------- let expression later in the condition
  |
help: add `let` before the expression
  |
3 |     if let Some(_) = x
  |        +++

---

Code

fn main() {
    let x = Some(42);
    if let Some(_) = x
        && Some(x) = x
    {}
}

Current output

Update:

error: expected expression, found `let` statement
 --> src/main.rs:3:8
  |
3 |     if let Some(_) = x
  |        ^^^^^^^^^^^^^^^
  |
  = note: only supported directly in conditions of `if` and `while` expressions
help: you might have meant to continue the let-chain
  |
4 |         && let Some(x) = x
  |            +++
help: you might have meant to compare for equality
  |
4 |         && Some(x) == x
  |                     +

error[E0308]: mismatched types
 --> src/main.rs:4:12
  |
4 |         && Some(x) = x
  |            ^^^^^^^ expected `bool`, found `Option<Option<{integer}>>`
  |
  = note: expected type `bool`
             found enum `Option<Option<{integer}>>`
help: use `Option::is_some` to test if the `Option` has a value
  |
4 |         && Some(x).is_some() = x
  |                   ++++++++++

error[E0308]: mismatched types
 --> src/main.rs:3:8
  |
3 |       if let Some(_) = x
  |  ________^
4 | |         && Some(x) = x
  | |______________________^ expected `bool`, found `()`

Previously:

error: expected expression, found `let` statement
 --> src/main.rs:3:8
  |
3 |     if let Some(_) = x
  |        ^^^^^^^^^^^^^^^
  |
  = note: only supported directly in conditions of `if` and `while` expressions

error[E0308]: mismatched types
 --> src/main.rs:4:12
  |
4 |         && Some(x) = x
  |            ^^^^^^^ expected `bool`, found `Option<Option<{integer}>>`
  |
  = note: expected type `bool`
             found enum `Option<Option<{integer}>>`
help: use `Option::is_some` to test if the `Option` has a value
  |
4 |         && Some(x).is_some() = x
  |                   ++++++++++

error[E0308]: mismatched types
 --> src/main.rs:3:8
  |
3 |       if let Some(_) = x
  |  ________^
4 | |         && Some(x) = x
  | |______________________^ expected `bool`, found `()`

Desired output

Edit: we now provide appropriate suggestions in the first diagnostic, but we should notice that this should have been a let chain and silence the E0308 errors.

error: let-chain with missing `let`
 --> src/main.rs:3:8
  |
3 |     if let Some(_) = x
  |        --------------- let-chain starting here
4 |         && Some(x) = x
  |            ^^^^^^^^^^^ expected `let` expression, found assignment
  |
help: add `let` before the expression
  |
4 |         && let Some(x) = x
  |            +++

Rationale and extra context

No response

Other cases

No response

Anything else?

No response

[obeis]

Current output

error: expected expression, found `let` statement
 --> let-chain.rs:3:8
  |
3 |     if let Some(_) = x
  |        ^^^^^^^^^^^^^^^
  |
  = note: only supported directly in conditions of `if` and `while` expressions
help: you might have meant to continue the let-chain
  |
4 |         && let Some(x) = x
  |            +++
help: you might have meant to compare for equality
  |
4 |         && Some(x) == x
  |                     +

error[E0308]: mismatched types
 --> let-chain.rs:4:12
  |
4 |         && Some(x) = x
  |            ^^^^^^^ expected `bool`, found `Option<Option<{integer}>>`
  |
  = note: expected type `bool`
             found enum `Option<Option<{integer}>>`
help: use `Option::is_some` to test if the `Option` has a value
  |
4 |         && Some(x).is_some() = x
  |                   ++++++++++

error[E0308]: mismatched types
 --> let-chain.rs:3:8
  |
3 |       if let Some(_) = x
  |  ________^
4 | |         && Some(x) = x
  | |______________________^ expected `bool`, found `()`

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0308`.