Handle indented block comments with ASCII art correctly.

Sources/SwiftFormat/Core/DocumentationCommentText.swift

@@ -67,24 +67,7 @@ public struct DocumentationCommentText {
     // comment. We have to copy it into an array since `Trivia` doesn't support bidirectional
     // indexing.
     let triviaArray = Array(trivia)
-    let commentStartIndex: Array<TriviaPiece>.Index
-    if
-      let lastNonDocCommentIndex = triviaArray.lastIndex(where: {
-        switch $0 {
-        case .docBlockComment, .docLineComment,
-            .newlines(1), .carriageReturns(1), .carriageReturnLineFeeds(1),
-            .spaces, .tabs:
-          return false
-        default:
-          return true
-        }
-      }),
-      lastNonDocCommentIndex != trivia.endIndex
-    {
-      commentStartIndex = triviaArray.index(after: lastNonDocCommentIndex)
-    } else {
-      commentStartIndex = triviaArray.startIndex
-    }
+    let commentStartIndex = findCommentStartIndex(triviaArray)
 
     // Determine the indentation level of the first line of the comment. This is used to adjust
     // block comments, whose text spans multiple lines.
@@ -216,3 +199,37 @@ private func asciiArtLength(of string: Substring, leadingSpaces: Int) -> Int {
   }
   return 0
 }
+
+/// Returns the start index of the earliest comment in the Trivia if we work backwards and
+/// skip through comments, newlines, and whitespace. Then we advance a bit forward to be sure
+/// the returned index is actually a comment and not whitespace.
+private func findCommentStartIndex(_ triviaArray: Array<TriviaPiece>) -> Array<TriviaPiece>.Index {
+  func firstCommentIndex(_ slice: ArraySlice<TriviaPiece>) -> Array<TriviaPiece>.Index {
+    return slice.firstIndex(where: {
+      switch $0 {
+      case .docLineComment, .docBlockComment:
+        return true
+      default:
+        return false
+      }
+    }) ?? slice.endIndex
+  }
+
+  if
+    let lastNonDocCommentIndex = triviaArray.lastIndex(where: {
+      switch $0 {
+      case .docBlockComment, .docLineComment,
+          .newlines(1), .carriageReturns(1), .carriageReturnLineFeeds(1),
+          .spaces, .tabs:
+        return false
+      default:
+        return true
+      }
+    })
+  {
+    let nextIndex = triviaArray.index(after: lastNonDocCommentIndex)
+    return firstCommentIndex(triviaArray[nextIndex...])
+  } else {
+    return firstCommentIndex(triviaArray[...])
+  }
+}

Tests/SwiftFormatTests/Core/DocumentationCommentTextTests.swift

@@ -54,7 +54,25 @@ final class DocumentationCommentTextTests: XCTestCase {
       """
     )
   }
-
+
+  func testIndentedDocBlockCommentWithASCIIArt() throws {
+    let decl: DeclSyntax = """
+        /**
+         * A simple doc comment.
+         */
+        func f() {}
+      """
+    let commentText = try XCTUnwrap(DocumentationCommentText(extractedFrom: decl.leadingTrivia))
+    XCTAssertEqual(commentText.introducer, .block)
+    XCTAssertEqual(
+      commentText.text,
+      """
+      A simple doc comment.
+
+      """
+    )
+  }
+
   func testDocBlockCommentWithoutASCIIArt() throws {
     let decl: DeclSyntax = """
       /**

Tests/SwiftFormatTests/Rules/BeginDocumentationCommentWithOneLineSummaryTests.swift

@@ -14,33 +14,33 @@ final class BeginDocumentationCommentWithOneLineSummaryTests: LintOrFormatRuleTe
     assertLint(
       BeginDocumentationCommentWithOneLineSummary.self,
       """
-      /// Returns a bottle of Dr Pepper from the vending machine.
-      public func drPepper(from vendingMachine: VendingMachine) -> Soda {}
+        /// Returns a bottle of Dr Pepper from the vending machine.
+        public func drPepper(from vendingMachine: VendingMachine) -> Soda {}
 
-      /// Contains a comment as description that needs a sentence
-      /// of two lines of code.
-      public var twoLinesForOneSentence = "test"
+        /// Contains a comment as description that needs a sentence
+        /// of two lines of code.
+        public var twoLinesForOneSentence = "test"
 
-      /// The background color of the view.
-      var backgroundColor: UIColor
+        /// The background color of the view.
+        var backgroundColor: UIColor
 
-      /// Returns the sum of the numbers.
-      ///
-      /// - Parameter numbers: The numbers to sum.
-      /// - Returns: The sum of the numbers.
-      func sum(_ numbers: [Int]) -> Int {
-      // ...
-      }
+        /// Returns the sum of the numbers.
+        ///
+        /// - Parameter numbers: The numbers to sum.
+        /// - Returns: The sum of the numbers.
+        func sum(_ numbers: [Int]) -> Int {
+        // ...
+        }
 
-      /// This docline should not succeed.
-      /// There are two sentences without a blank line between them.
-      1️⃣struct Test {}
+        /// This docline should not succeed.
+        /// There are two sentences without a blank line between them.
+        1️⃣struct Test {}
 
-      /// This docline should not succeed. There are two sentences.
-      2️⃣public enum Token { case comma, semicolon, identifier }
+        /// This docline should not succeed. There are two sentences.
+        2️⃣public enum Token { case comma, semicolon, identifier }
 
-      /// Should fail because it doesn't have a period
-      3️⃣public class testNoPeriod {}
+        /// Should fail because it doesn't have a period
+        3️⃣public class testNoPeriod {}
       """,
       findings: [
         FindingSpec("1️⃣", message: #"add a blank comment line after this sentence: "This docline should not succeed.""#),
@@ -54,36 +54,36 @@ final class BeginDocumentationCommentWithOneLineSummaryTests: LintOrFormatRuleTe
     assertLint(
       BeginDocumentationCommentWithOneLineSummary.self,
       """
-      /**
-       * Returns the numeric value.
-       *
-       * - Parameters:
-       *   - digit: The Unicode scalar whose numeric value should be returned.
-       *   - radix: The radix, between 2 and 36, used to compute the numeric value.
-       * - Returns: The numeric value of the scalar.*/
-      func numericValue(of digit: UnicodeScalar, radix: Int = 10) -> Int {}
-
-      /**
-       * This block comment contains a sentence summary
-       * of two lines of code.
-       */
-      public var twoLinesForOneSentence = "test"
-
-      /**
-       * This block comment should not succeed, struct.
-       * There are two sentences without a blank line between them.
-       */
-      1️⃣struct TestStruct {}
-
-      /**
-      This block comment should not succeed, class.
-      Add a blank comment after the first line.
-      */
-      2️⃣public class TestClass {}
-      /** This block comment should not succeed, enum. There are two sentences. */
-      3️⃣public enum testEnum {}
-      /** Should fail because it doesn't have a period */
-      4️⃣public class testNoPeriod {}
+        /**
+         * Returns the numeric value.
+         *
+         * - Parameters:
+         *   - digit: The Unicode scalar whose numeric value should be returned.
+         *   - radix: The radix, between 2 and 36, used to compute the numeric value.
+         * - Returns: The numeric value of the scalar.*/
+        func numericValue(of digit: UnicodeScalar, radix: Int = 10) -> Int {}
+
+        /**
+         * This block comment contains a sentence summary
+         * of two lines of code.
+         */
+        public var twoLinesForOneSentence = "test"
+
+        /**
+         * This block comment should not succeed, struct.
+         * There are two sentences without a blank line between them.
+         */
+        1️⃣struct TestStruct {}
+
+        /**
+        This block comment should not succeed, class.
+        Add a blank comment after the first line.
+        */
+        2️⃣public class TestClass {}
+        /** This block comment should not succeed, enum. There are two sentences. */
+        3️⃣public enum testEnum {}
+        /** Should fail because it doesn't have a period */
+        4️⃣public class testNoPeriod {}
       """,
       findings: [
         FindingSpec("1️⃣", message: #"add a blank comment line after this sentence: "This block comment should not succeed, struct.""#),