Make unneeded_break_in_switch auto correctable (#5188)

CHANGELOG.md

@@ -17,6 +17,9 @@
   [gibachan](https://github.com/gibachan)
   [#5233](https://github.com/realm/SwiftLint/pull/5233)
 
+* Make `unneeded_break_in_switch` auto correctable.  
+  [KS1019](https://github.com/KS1019/)
+
 #### Bug Fixes
 
 * Fix false positive in `unused_import` rule that triggered on 

Source/SwiftLintBuiltInRules/Rules/Idiomatic/UnneededBreakInSwitchRule.swift

@@ -12,7 +12,7 @@ private func embedInSwitch(
         """, file: file, line: line)
 }
 
-struct UnneededBreakInSwitchRule: SwiftSyntaxRule, ConfigurationProviderRule {
+struct UnneededBreakInSwitchRule: SwiftSyntaxCorrectableRule, ConfigurationProviderRule {
     var configuration = SeverityConfiguration<Self>(.warning)
 
     static let description = RuleDescription(
@@ -45,23 +45,121 @@ struct UnneededBreakInSwitchRule: SwiftSyntaxRule, ConfigurationProviderRule {
             embedInSwitch("something()\n    ↓break // comment"),
             embedInSwitch("something()\n    ↓break", case: "default"),
             embedInSwitch("something()\n    ↓break", case: "case .foo, .foo2 where condition")
+        ],
+        corrections: [
+            embedInSwitch("something()\n    ↓break")
+            : embedInSwitch("something()"),
+            embedInSwitch("something()\n    ↓break // line comment")
+            : embedInSwitch("something()\n     // line comment"),
+            embedInSwitch("""
+                something()
+                ↓break
+                /*
+                block comment
+                */
+                """)
+            : embedInSwitch("""
+                something()
+                /*
+                block comment
+                */
+                """),
+            embedInSwitch("something()\n    ↓break /// doc line comment")
+            : embedInSwitch("something()\n     /// doc line comment"),
+            embedInSwitch("""
+                something()
+                ↓break
+                ///
+                /// doc block comment
+                ///
+                """)
+            : embedInSwitch("""
+                something()
+                ///
+                /// doc block comment
+                ///
+                """),
+            embedInSwitch("something()\n    ↓break", case: "default")
+            : embedInSwitch("something()", case: "default"),
+            embedInSwitch("something()\n    ↓break", case: "case .foo, .foo2 where condition")
+            : embedInSwitch("something()", case: "case .foo, .foo2 where condition")
         ]
     )
 
     func makeVisitor(file: SwiftLintFile) -> ViolationsSyntaxVisitor {
         UnneededBreakInSwitchRuleVisitor(viewMode: .sourceAccurate)
     }
+
+    func makeRewriter(file: SwiftLintCore.SwiftLintFile) -> SwiftLintCore.ViolationsSyntaxRewriter? {
+        UnneededBreakInSwitchRewriter(
+            locationConverter: file.locationConverter,
+            disabledRegions: disabledRegions(file: file)
+        )
+    }
 }
 
 private final class UnneededBreakInSwitchRuleVisitor: ViolationsSyntaxVisitor {
     override func visitPost(_ node: SwitchCaseSyntax) {
-        guard node.statements.count > 1,
-              let statement = node.statements.last,
-              let breakStatement = statement.item.as(BreakStmtSyntax.self),
-              breakStatement.label == nil else {
+        guard let statement = node.unneededBreak else {
             return
         }
 
         violations.append(statement.item.positionAfterSkippingLeadingTrivia)
     }
 }
+
+private final class UnneededBreakInSwitchRewriter: SyntaxRewriter, ViolationsSyntaxRewriter {
+    private(set) var correctionPositions: [SwiftSyntax.AbsolutePosition] = []
+    let locationConverter: SourceLocationConverter
+    let disabledRegions: [SourceRange]
+
+    init(locationConverter: SourceLocationConverter, disabledRegions: [SourceRange]) {
+        self.locationConverter = locationConverter
+        self.disabledRegions = disabledRegions
+    }
+
+    override func visit(_ node: SwitchCaseSyntax) -> SwitchCaseSyntax {
+        let stmts = CodeBlockItemListSyntax(node.statements.dropLast())
+
+        guard let breakStatement = node.unneededBreak, let secondLast = stmts.last,
+              !node.isContainedIn(regions: disabledRegions, locationConverter: locationConverter) else {
+            return super.visit(node)
+        }
+
+        correctionPositions.append(breakStatement.item.positionAfterSkippingLeadingTrivia)
+
+        let trivia = breakStatement.item.leadingTrivia + breakStatement.item.trailingTrivia
+
+        let newNode = node
+            .with(\.statements, stmts)
+            .with(\.statements.trailingTrivia, secondLast.item.trailingTrivia + trivia)
+            .trimmed { !$0.isComment }
+            .formatted()
+            .as(SwitchCaseSyntax.self)!
+
+        return super.visit(newNode)
+    }
+}
+
+private extension SwitchCaseSyntax {
+    var unneededBreak: CodeBlockItemSyntax? {
+        guard statements.count > 1,
+              let breakStatement = statements.last?.item.as(BreakStmtSyntax.self),
+              breakStatement.label == nil else {
+            return nil
+        }
+
+        return statements.last
+    }
+}
+
+private extension TriviaPiece {
+    var isComment: Bool {
+        switch self {
+        case .lineComment, .blockComment, .docLineComment, .docBlockComment:
+            return true
+        default:
+            return false
+        }
+    }
+}