New Issue Checklist

• Updated SwiftLint to the latest version
• I searched for existing GitHub issues

New rule request

1. Why should this rule be added?

This rule should flag conditions that are used multiple times in the same branching statement like if-else-if or switch statement.

2. Provide several examples of what would and wouldn't trigger violations.

Violating Examples

if x < 5 {
  foo()
} else if x < 2 {
  bar()
} else if x < 5 { // duplicated condition
  baz()
}

switch x {
case "a":
  foo()
case "a" // duplicated condition
  bar()
}

Non-Violating Examples

if x < 5 {
  foo()
  baz()
} else if x < 2 {
  bar()
}

switch x {
case "a":
  foo()
  bar()
}

3. Should the rule be configurable, if so what parameters should be configurable?

This rule doesn’t need to be configurable.

4. Should the rule be opt-in or enabled by default? Why?
   See README.md for guidelines on when to mark a rule as opt-in.

This would be a good candidate for a builtin rule as it points out bad structured code.