Clarify that the rule applies to both local variables and instance pr…

…operties, simplify examples

README.md

@@ -340,6 +340,13 @@ _You can enable the following settings in Xcode by running [this script](resourc
   let sun = Star(mass: 1.989e30)
   let earth = Planet.earth
 
+  // NOT RECOMMENDED. However, since the linter doesn't have full type information, this is not enforced automatically.
+  let moon: Moon = earth.moon // returns `Moon`
+
+  // RIGHT
+  let moon = earth.moon
+  let moon: PlanetaryBody? = earth.moon
+
   // WRONG: Most literals provide a default type that can be inferred.
   let enableGravity: Bool = true
   let numberOfPlanets: Int = 8
@@ -369,70 +376,79 @@ _You can enable the following settings in Xcode by running [this script](resourc
 
   </details>
 
-* <a id='infer-property-types'></a>(<a href='#infer-property-types'>link</a>) **Prefer letting the type of a property be inferred from the right-hand-side value rather than writing the type explicitly on the left-hand side.** [![SwiftFormat: preferInferredTypes](https://img.shields.io/badge/SwiftFormat-preferInferredTypes-7B0051.svg)](https://github.com/nicklockwood/SwiftFormat/blob/master/Rules.md#preferInferredTypes)
+* <a id='infer-property-types'></a>(<a href='#infer-property-types'>link</a>) **Prefer letting the type of a variable or property be inferred from the right-hand-side value rather than writing the type explicitly on the left-hand side.** [![SwiftFormat: preferInferredTypes](https://img.shields.io/badge/SwiftFormat-preferInferredTypes-7B0051.svg)](https://github.com/nicklockwood/SwiftFormat/blob/master/Rules.md#preferInferredTypes)
 
   <details>
 
+  Prefer using inferred types when the right-hand-side value is a static member with a leading dot (e.g. an `init`, a `static` property / function, or an enum case). This applies to both local variables and property declarations:
+
   ```swift
   // WRONG
-  let sun: Star = .init(mass: 1.989e30)
-  let earth: Planet = .earth
+  struct SolarSystemBuilder {
+    let sun: Star = .init(mass: 1.989e30)
+    let earth: Planet = .earth
 
+    func setUp() {
+      let galaxy: Galaxy = .andromeda
+      let system: SolarSystem = .init(sun, earth)
+      galaxy.add(system)
+    }
+  }
+
   // RIGHT
-  let sun = Star(mass: 1.989e30)
-  let earth = Planet.earth
+  struct SolarSystemBuilder {
+    let sun = Star(mass: 1.989e30)
+    let earth = Planet.earth
 
-  // ALSO RIGHT: Explicit types are required when there is no right-hand-side value.
-  let sun: Star
-  let earth: Planet
-
-  // ALSO RIGHT: Explicit types can be necessary when the right-hand side has
-  // a different type from the one written explicitly on the left-hand side.
-  let naturalSatellite: PlanetaryBody? = Moon(mass: 7.347e22)
-  let moon: PlanetaryBody? = nil // nil literals are typeless
-  let numberOfPlanets: UInt = 8 // integer literals default to `Int`
-  let sunMass: CGFloat = 1.989e30 // floating-point literals default to `Double`
-  let planets: [Planet] = [] // empty collection literals are typeless
-
-  // ALSO RIGHT: Some of the examples above can also be written idiomatically without an explicit type on
-  // the left-hand-side, by instead giving the right-hand side value an explicit type. Either style is fine.
-  let numberOfPlanets = UInt(8)
-  let sunMass = CGFloat(1.989e30)
-  let planets = [Planet]()
+    func setUp() {
+      let galaxy = Galaxy.andromeda
+      let system = SolarSystem(sun, earth)
+      galaxy.add(system)
+    }
+  }
   ```
-  
-  There are some rarer cases where the inferred type syntax has a different meaning than the explicit type syntax. In these cases, the explicit type syntax is still permitted:
-  
+
+  Explicit types are still permitted in other cases:
+
   ```swift
-  extension String {
-    static let earth = "Earth"
-  }
+  // RIGHT: There is no right-hand-side value, so an explicit type is required.
+  let sun: Star
 
-  // RIGHT: If the property's type is optional, moving the optional type 
-  // to the right-hand side may result in invalid code.  
-  let planetName: String? = .earth
-
+  // RIGHT: The right-hand-side is not a static member of the left-hand type.
+  let moon: PlantaryBody = earth.moon
+  let sunMass: Float = 1.989e30
+  let planets: [Planet] = []
+  let venusMoon: Moon? = nil
+  ```
+
+  There are some rare cases where the inferred type syntax has a different meaning than the explicit type syntax. In these cases, the explicit type syntax is still permitted:
+
+  ```swift
   // WRONG: fails with "error: type 'String?' has no member 'foo'"
+  // if `earth` is defined in an extension on `String` rather than `Optional<String>`.
   let planetName = String?.earth
+
+  // RIGHT
+  let planetName: String? = .earth
   ```
-  
+
   ```swift
   struct SaturnOutline: ShapeStyle { ... }
-  
+
   extension ShapeStyle where Self == SaturnOutline {
     static var saturnOutline: SaturnOutline { 
       SaturnOutline() 
     }
   }
-
+
+  // WRONG: fails with "error: static member 'saturnOutline' cannot be used on protocol metatype '(any ShapeStyle).Type'"
+  let myShape2 = (any ShapeStyle).myShape
+
   // RIGHT: If the property's type is an existential / protocol type, moving the type
   // to the right-hand side will result in invalid code if the value is defined in an
   // extension like `extension ShapeStyle where Self == SaturnOutline`.
   // SwiftFormat autocorrect detects this case by checking for the existential `any` keyword.
   let myShape1: any ShapeStyle = .saturnOutline
-
-  // WRONG: fails with "error: static member 'saturnOutline' cannot be used on protocol metatype '(any ShapeStyle).Type'"
-  let myShape2 = (any ShapeStyle).myShape
   ```
 
   </details>