Add Generated Code comment and attribute (#215)

* Add autogenerated indicators

Adds autogenerated comment to the beginning of generated files
Adds GeneratedCodeAttribute before generated methods

Fixes #214

* Update Directory.Build.props

---------

Co-authored-by: Domn Werner <domn.werner@gmail.com>

src/Dunet.Generator/UnionExtensionsGeneration/UnionExtensionsSourceBuilder.cs

@@ -18,11 +18,13 @@ public static string GenerateExtensions(UnionDeclaration union)
  }
 
  return new StringBuilder()
+ .AppendAutoGeneratedComment()
  .AppendLine("#pragma warning disable 1591")
  .AppendUsingStatements(union)
  .AppendLine()
  .AppendLine($"namespace {union.Namespace};")
  .AppendLine()
+ .AppendGeneratedCodeAttribute()
  .AppendExtensionClassDeclaration(union)
  .AppendLine("{")
  .AppendMatchAsyncMethodForFuncs(union, task)

src/Dunet.Generator/UnionGeneration/StringBuilderExtensions.cs

@@ -1,4 +1,5 @@
-using System.Text;
+using System.Reflection;
+using System.Text;
 
 namespace Dunet.Generator.UnionGeneration;
 
@@ -41,4 +42,29 @@ public static void AppendFullUnionName(this StringBuilder builder, UnionDeclarat
 
  builder.Append(union.Name);
  }
+
+ public static StringBuilder AppendAutoGeneratedComment(this StringBuilder builder)
+ {
+ builder.AppendLine("// <auto-generated/>");
+ return builder;
+ }
+
+ /// <summary>
+ /// Appends the GeneratedCodeAttribute, to better enable the code to be detected as generated.
+ /// </summary>
+ /// <param name="builder">The string builder to append to.</param>
+ public static StringBuilder AppendGeneratedCodeAttribute(this StringBuilder builder)
+ {
+ builder.AppendLine($"[global::System.CodeDom.Compiler.GeneratedCodeAttribute(\"Dunet.Generator\", \"{GeneratorVersion}\")]");
+ return builder;
+ }
+
+ private static string? GeneratorVersion { get; } = GetGeneratorVersion();
+
+ private static string? GetGeneratorVersion()
+ {
+ var assembly = typeof(UnionGenerator).Assembly;
+ var attribute = assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>();
+ return attribute?.InformationalVersion;
+ }
 }

src/Dunet.Generator/UnionGeneration/UnionSourceBuilder.cs

@@ -8,6 +8,8 @@ public static string Build(UnionDeclaration union)
  {
  var builder = new StringBuilder();
 
+ builder.AppendAutoGeneratedComment();
+
  builder.AppendLine("#pragma warning disable 1591");
 
  foreach (var import in union.Imports)
@@ -28,6 +30,7 @@ public static string Build(UnionDeclaration union)
  builder.AppendLine("{");
  }
 
+ builder.AppendGeneratedCodeAttribute();
  builder.Append($"abstract partial record {union.Name}");
  builder.AppendTypeParams(union.TypeParameters);
  builder.AppendLine();