PrettyPrinter reports wrong line LineNumbersTests

The reason for the wrong line number were multiline
comments.
In to accomodate for this, we now check the string
while writing for new lines and increment the line
count accordingly.

Issue: swiftlang#882

Sources/SwiftFormat/PrettyPrint/PrettyPrintBuffer.swift

@@ -118,7 +118,20 @@ struct PrettyPrintBuffer {
     writeRaw(text)
     consecutiveNewlineCount = 0
     pendingSpaces = 0
-    column += text.count
+
+    // In case of comments, we may get a multi-line string.
+    // To account for that case, we need to correct the lineNumber count.
+    // The new column is only the position within the last line.
+    let lines = text.split(separator: "\n")
+    lineNumber += lines.count - 1
+    if lines.count > 1 {
+      // in case we have inserted new lines, we need to reset the column
+      column = lines.last?.count ?? 0
+    } else {
+      // in case it is an end of line comment or a single line comment,
+      // we just add to the current column
+      column += lines.last?.count ?? 0
+    }
   }
 
   /// Request that the given number of spaces be printed out before the next text token.

Tests/SwiftFormatTests/PrettyPrint/LineNumbersTests.swift

@@ -0,0 +1,80 @@
+import SwiftFormat
+import _SwiftFormatTestSupport
+
+final class LineNumbersTests: PrettyPrintTestCase {
+  func testLineNumbers() {
+    let input =
+      """
+      final class A {
+        @Test func b() throws {
+          doSomethingInAFunctionWithAVeryLongName()  1️⃣// Here we have a very long comment that should not be here because it is far too long
+        }
+      }
+      """
+
+      let expected =
+      """
+      final class A {
+        @Test func b() throws {
+          doSomethingInAFunctionWithAVeryLongName()  // Here we have a very long comment that should not be here because it is far too long
+        }
+      }
+      
+      """
+
+      assertPrettyPrintEqual(input: input,
+                             expected: expected,
+                             linelength: 120,
+                             whitespaceOnly: true,
+                             findings: [
+                                FindingSpec("1️⃣", message: "move end-of-line comment that exceeds the line length")
+                             ])
+  }
+
+  func testLineNumbersWithComments() {
+    let input =
+    """
+    // Copyright (C) 2024 My Coorp. All rights reserved.
+    //
+    // This document is the property of My Coorp.
+    // It is considered confidential and proprietary.
+    //
+    // This document may not be reproduced or transmitted in any form,
+    // in whole or in part, without the express written permission of
+    // My Coorp.
+    
+    final class A {
+      @Test func b() throws {
+        doSomethingInAFunctionWithAVeryLongName()  1️⃣// Here we have a very long comment that should not be here because it is far too long
+      }
+    }
+    """
+
+    let expected =
+    """
+    // Copyright (C) 2024 My Coorp. All rights reserved.
+    //
+    // This document is the property of My Coorp.
+    // It is considered confidential and proprietary.
+    //
+    // This document may not be reproduced or transmitted in any form,
+    // in whole or in part, without the express written permission of
+    // My Coorp.
+    
+    final class A {
+      @Test func b() throws {
+        doSomethingInAFunctionWithAVeryLongName()  // Here we have a very long comment that should not be here because it is far too long
+      }
+    }
+    
+    """
+
+    assertPrettyPrintEqual(input: input,
+                           expected: expected,
+                           linelength: 120,
+                           whitespaceOnly: true,
+                           findings: [
+                              FindingSpec("1️⃣", message: "move end-of-line comment that exceeds the line length")
+                           ])
+  }
+}