Rule suggestion: guard let instead of huge if let

[dbmrq]

Instead of something like:

if let aVariable = something, 
    anotherVariable = somethingElse {
        // A
        // huge
        // indented
        // body
        // of
        // code
}

I think it's generally better to do something like:

guard let aVariable = something, 
    anotherVariable = somethingElse else { return }

// A
// huge
// unindented
// body
// of
// code

There could be a limit to the number of lines inside the if let to trigger the rule.

[sfurlani]

I don't have any idea on how to contribute the logic towards this, but A simple pattern matching might look like this:

Triggering Examples

if let x {
  /* code using x goes here */
} else {
  /* parent context exit logic */
    // return
    // continue
    // break
    // throw 
}

/* parent context opens */
{
  /* any number of statements */
  if let x {
     /* code using x goes here */
  }
  /* no other statements before parent context closes */
}

Untriggering Example

guard let x else {
  /* context exit logic */
    // return
    // continue
    // break
    // throw 
}
/* code using x goes here */

/* parent context opens */
{
  /* any number of statements */
  guard let x else {
    /* context exit logic */
    // return
    // continue
    // break
    // throw
  }
  /* code using x goes here */
}

It won't catch all cases, but it'll find the simplest cases that can be defined as warnings or errors.

[Uncommon]

Note that it's also possible to have:

if x < 5,
   let a = something {