Comment every line of a multi-line copyright, and refuse a multi-line region name [patch]

CodeBlocker.Test/CodeBlockerExtensionsTests.cs

@@ -35,6 +35,36 @@ public void AutoGeneratedHeaderPutsTheCopyrightAboveTheMarker()
 			codeBlocker.ToString());
 	}
 
+	[TestMethod]
+	[DataRow("\n", DisplayName = "LF")]
+	[DataRow("\r\n", DisplayName = "CRLF")]
+	[DataRow("\r", DisplayName = "CR")]
+	[DataRow("\u0085", DisplayName = "NEL")]
+	[DataRow("\u2028", DisplayName = "LINE SEPARATOR")]
+	[DataRow("\u2029", DisplayName = "PARAGRAPH SEPARATOR")]
+	public void AutoGeneratedHeaderCommentsEveryLineOfAMultiLineCopyright(string terminator)
+	{
+		using CodeBlocker codeBlocker = Create();
+
+		codeBlocker.WriteAutoGeneratedHeader($"Copyright (c) 2026 Acme Corp.{terminator}All rights reserved.");
+
+		Assert.AreEqual(
+			"// Copyright (c) 2026 Acme Corp.\n// All rights reserved.\n// <auto-generated />\n\n",
+			codeBlocker.ToString());
+	}
+
+	[TestMethod]
+	public void AutoGeneratedHeaderWritesABlankCopyrightLineAsABareComment()
+	{
+		using CodeBlocker codeBlocker = Create();
+
+		codeBlocker.WriteAutoGeneratedHeader("SPDX-License-Identifier: MIT\n\nCopyright (c) 2026 Acme Corp.");
+
+		Assert.AreEqual(
+			"// SPDX-License-Identifier: MIT\n//\n// Copyright (c) 2026 Acme Corp.\n// <auto-generated />\n\n",
+			codeBlocker.ToString());
+	}
+
 	[TestMethod]
 	public void NullableDirectivesAreWrittenVerbatim()
 	{

CodeBlocker.Test/ScopesTests.cs

@@ -90,6 +90,22 @@ public void RegionScopeWithoutANameOmitsTheTrailingSpace()
 		Assert.AreEqual("#region\nint x;\n#endregion\n", codeBlocker.ToString());
 	}
 
+	[TestMethod]
+	[DataRow("\n", DisplayName = "LF")]
+	[DataRow("\r\n", DisplayName = "CRLF")]
+	[DataRow("\r", DisplayName = "CR")]
+	[DataRow("\u0085", DisplayName = "NEL")]
+	[DataRow("\u2028", DisplayName = "LINE SEPARATOR")]
+	[DataRow("\u2029", DisplayName = "PARAGRAPH SEPARATOR")]
+	public void RegionScopeRejectsANameThatSpansLinesBeforeWriting(string terminator)
+	{
+		using CodeBlocker codeBlocker = Create();
+
+		Assert.ThrowsExactly<ArgumentException>(() => new RegionScope(codeBlocker, $"a{terminator}b"));
+
+		Assert.AreEqual(string.Empty, codeBlocker.ToString());
+	}
+
 	[TestMethod]
 	public void DirectiveScopeWrapsTheBodyInAConditional()
 	{

CodeBlocker/CodeBlockerExtensions.cs

@@ -19,18 +19,23 @@ public static class CodeBlockerExtensions
 	/// </summary>
 	/// <param name="codeBlocker">The <see cref="CodeBlocker"/> to write to.</param>
 	/// <param name="copyright">
-	/// An optional copyright line written above the marker, without its <c>//</c> prefix. Pass the
-	/// same text the consuming repository's file header template uses.
+	/// An optional copyright notice written above the marker, without its <c>//</c> prefix. Pass the
+	/// same text the consuming repository's file header template uses. A notice of several lines is
+	/// written as one comment line each, split at every terminator the C# compiler recognises, and an
+	/// empty line becomes a bare <c>//</c>.
 	/// </param>
 	/// <returns>The same <see cref="CodeBlocker"/>, for chaining.</returns>
 	/// <exception cref="ArgumentNullException"><paramref name="codeBlocker"/> is <see langword="null"/>.</exception>
 	public static CodeBlocker WriteAutoGeneratedHeader(this CodeBlocker codeBlocker, string? copyright = null)
 	{
 		Ensure.NotNull(codeBlocker);
 
-		if (!string.IsNullOrEmpty(copyright))
+		if (copyright is { Length: > 0 })
 		{
-			codeBlocker.WriteLine($"// {copyright}");
+			foreach (string line in LineTerminators.Split(copyright))
+			{
+				codeBlocker.WriteLine(line.Length == 0 ? "//" : $"// {line}");
+			}
 		}
 
 		codeBlocker.WriteLine("// <auto-generated />");

CodeBlocker/LineTerminators.cs

@@ -0,0 +1,36 @@
+// Copyright (c) 2023-2026 ktsu-dev contributors
+
+namespace ktsu.CodeBlocker;
+
+/// <summary>
+/// The characters the C# compiler ends a line at, for text that has to stay inside a single-line
+/// comment or directive.
+/// </summary>
+internal static class LineTerminators
+{
+	/// <summary>
+	/// Every line terminator the C# compiler recognises: LF, CR, NEL (U+0085), LINE SEPARATOR
+	/// (U+2028) and PARAGRAPH SEPARATOR (U+2029). CRLF is a pair of these.
+	/// </summary>
+	private static readonly char[] Characters = ['\n', '\r', '\u0085', '\u2028', '\u2029'];
+
+	/// <summary>
+	/// Splits text into lines at every terminator the C# compiler recognises: either platform's
+	/// line ending, so that a caller's verbatim or raw string literal lays out the same way
+	/// whichever platform the source file was written on, and also NEL (U+0085), LINE SEPARATOR
+	/// (U+2028) and PARAGRAPH SEPARATOR (U+2029). The compiler ends a <c>//</c> or <c>///</c>
+	/// comment at any of those, so left inside a line they would push the rest of the text out of
+	/// the comment and into the code.
+	/// </summary>
+	/// <param name="text">The text to split.</param>
+	/// <returns>The lines, without their terminators. Text with no terminator is a single line.</returns>
+	internal static string[] Split(string text) =>
+		text.Replace("\r\n", "\n").Split(Characters);
+
+	/// <summary>
+	/// Reports whether text contains any line terminator the C# compiler recognises.
+	/// </summary>
+	/// <param name="text">The text to check.</param>
+	/// <returns><see langword="true"/> if <paramref name="text"/> would span more than one line.</returns>
+	internal static bool Contains(string text) => text.IndexOfAny(Characters) >= 0;
+}

CodeBlocker/Scopes.cs

@@ -105,12 +105,21 @@ private static void End(CodeBlocker codeBlocker)
 /// </remarks>
 /// <param name="codeBlocker">The parent <see cref="CodeBlocker"/>.</param>
 /// <param name="name">The region name.</param>
+/// <exception cref="ArgumentException">
+/// <paramref name="name"/> contains a line terminator, which would leave the rest of the name outside
+/// the directive. Nothing is written.
+/// </exception>
 public class RegionScope(CodeBlocker codeBlocker, string name)
 	: ScopedAction(onOpen: () => Begin(codeBlocker, name), onClose: () => End(codeBlocker))
 {
 	private static void Begin(CodeBlocker codeBlocker, string name)
 	{
 		Ensure.NotNull(codeBlocker);
+		if (name is not null && LineTerminators.Contains(name))
+		{
+			throw new ArgumentException("A region name must fit on the #region line.", nameof(name));
+		}
+
 		codeBlocker.WriteLine(string.IsNullOrEmpty(name) ? "#region" : $"#region {name}");
 	}
 

CodeBlocker/Templates/DocComment.cs

@@ -202,7 +202,7 @@ private void WriteElement(CodeBlocker codeBlocker, string tagName, string? attri
 	/// <param name="text">The element's content.</param>
 	private void WriteNamedElement(CodeBlocker codeBlocker, string tagName, string? attributes, string? text)
 	{
-		string[] lines = SplitLines(text ?? string.Empty);
+		string[] lines = LineTerminators.Split(text ?? string.Empty);
 		if (lines.Length == 1)
 		{
 			codeBlocker.WriteLine($"/// <{tagName}{attributes}>{Escape(lines[0])}</{tagName}>");
@@ -220,19 +220,6 @@ private void WriteNamedElement(CodeBlocker codeBlocker, string tagName, string?
 
 	private string Escape(string text) => EscapeText ? EscapeContent(text) : text;
 
-	/// <summary>
-	/// Splits text into lines at every terminator the C# compiler recognises: either platform's
-	/// line ending, so that a caller's verbatim or raw string literal lays out the same way
-	/// whichever platform the source file was written on, and also NEL (U+0085), LINE SEPARATOR
-	/// (U+2028) and PARAGRAPH SEPARATOR (U+2029). The compiler ends a <c>///</c> comment at any of
-	/// those, so left inside a line they would push the rest of the text out of the comment and
-	/// into the code.
-	/// </summary>
-	/// <param name="text">The text to split.</param>
-	/// <returns>The text's lines.</returns>
-	private static string[] SplitLines(string text) =>
-		text.Replace("\r\n", "\n").Split('\n', '\r', '\u0085', '\u2028', '\u2029');
-
 	/// <summary>
 	/// Escapes the characters that would otherwise be read as markup in element content.
 	/// </summary>