Merge pull request #2194 from dabelknap/no-fallthrough-only

Add "No Fallthrough Only" Rule

CHANGELOG.md

@@ -13,6 +13,9 @@
 
 * Updates the `untyped_error_in_catch` rule to support autocorrection.  
   [Daniel Metzing](https://github.com/dirtydanee)
+* Add `no-fallthrough-only` rule to check that `case` statements do not contain
+  only a `fallthrough`.  
+  [Austin Belknap](https://github.com/dabelknap)
 
 * Add `indented_cases` support to `switch_case_alignment` rule.  
   [Shai Mishali](https://github.com/freak4pc)

Rules.md

@@ -74,6 +74,7 @@
 * [Nesting](#nesting)
 * [Nimble Operator](#nimble-operator)
 * [No Extension Access Modifier](#no-extension-access-modifier)
+* [No Fallthrough Only](#no-fallthrough-only)
 * [No Grouping Extension](#no-grouping-extension)
 * [Notification Center Detachment](#notification-center-detachment)
 * [Number Separator](#number-separator)
@@ -10298,6 +10299,184 @@ extension String {}
 
 
 
+## No Fallthrough Only
+
+Identifier | Enabled by default | Supports autocorrection | Kind | Minimum Swift Compiler Version
+--- | --- | --- | --- | ---
+`no_fallthrough_only` | Enabled | No | idiomatic | 3.0.0 
+
+Fallthroughs can only be used if the `case` contains at least one other statement.
+
+### Examples
+
+<details>
+<summary>Non Triggering Examples</summary>
+
+```swift
+switch myvar {
+case 1:
+    var a = 1
+    fallthrough
+case 2:
+    var a = 2
+}
+```
+
+```swift
+switch myvar {
+case "a":
+    var one = 1
+    var two = 2
+    fallthrough
+case "b": /* comment */
+    var three = 3
+}
+```
+
+```swift
+switch myvar {
+case 1:
+   let one = 1
+case 2:
+   // comment
+   var two = 2
+}
+```
+
+```swift
+switch myvar {
+case MyFunc(x: [1, 2, YourFunc(a: 23)], y: 2):
+    var three = 3
+    fallthrough
+default:
+    var three = 4
+}
+```
+
+```swift
+switch myvar {
+case .alpha:
+    var one = 1
+case .beta:
+    var three = 3
+    fallthrough
+default:
+    var four = 4
+}
+```
+
+```swift
+let aPoint = (1, -1)
+switch aPoint {
+case let (x, y) where x == y:
+    let A = "A"
+case let (x, y) where x == -y:
+    let B = "B"
+    fallthrough
+default:
+    let C = "C"
+}
+```
+
+```swift
+switch myvar {
+case MyFun(with: { $1 }):
+    let one = 1
+    fallthrough
+case "abc":
+    let two = 2
+}
+```
+
+</details>
+<details>
+<summary>Triggering Examples</summary>
+
+```swift
+switch myvar {
+case 1:
+    ↓fallthrough
+case 2:
+    var a = 1
+}
+```
+
+```swift
+switch myvar {
+case 1:
+    var a = 2
+case 2:
+    ↓fallthrough
+case 3:
+    var a = 3
+}
+```
+
+```swift
+switch myvar {
+case 1: // comment
+    ↓fallthrough
+}
+```
+
+```swift
+switch myvar {
+case 1: /* multi
+    line
+    comment */
+    ↓fallthrough
+case 2:
+    var a = 2
+}
+```
+
+```swift
+switch myvar {
+case MyFunc(x: [1, 2, YourFunc(a: 23)], y: 2):
+    ↓fallthrough
+default:
+    var three = 4
+}
+```
+
+```swift
+switch myvar {
+case .alpha:
+    var one = 1
+case .beta:
+    ↓fallthrough
+case .gamma:
+    var three = 3
+default:
+  var four = 4
+}
+```
+
+```swift
+let aPoint = (1, -1)
+switch aPoint {
+case let (x, y) where x == y:
+    let A = "A"
+case let (x, y) where x == -y:
+    ↓fallthrough
+default:
+    let B = "B"
+}
+```
+
+```swift
+switch myvar {
+case MyFun(with: { $1 }):
+    ↓fallthrough
+case "abc":
+    let two = 2
+}
+```
+
+</details>
+
+
+
 ## No Grouping Extension
 
 Identifier | Enabled by default | Supports autocorrection | Kind | Minimum Swift Compiler Version

Source/SwiftLintFramework/Models/MasterRuleList.swift

@@ -1,4 +1,4 @@
-// Generated using Sourcery 0.11.2 — https://github.com/krzysztofzablocki/Sourcery
+// Generated using Sourcery 0.13.1 — https://github.com/krzysztofzablocki/Sourcery
 // DO NOT EDIT
 
 public let masterRuleList = RuleList(rules: [
@@ -75,6 +75,7 @@ public let masterRuleList = RuleList(rules: [
     NestingRule.self,
     NimbleOperatorRule.self,
     NoExtensionAccessModifierRule.self,
+    NoFallthroughOnlyRule.self,
     NoGroupingExtensionRule.self,
     NotificationCenterDetachmentRule.self,
     NumberSeparatorRule.self,