* Refactoring `GeneratedKind.Generated` to `GeneratedKind.MarkedGenerated`,...

* Refactoring `GeneratedKind.Generated` to `GeneratedKind.MarkedGenerated`, giving us better future ability to add something like `InferredGenerated` if we want to expose a heuristic.
* Added documentation comments.

src/Compilers/CSharp/Portable/Syntax/CSharpSyntaxTree.cs

@@ -725,7 +725,7 @@ internal bool IsGeneratedCode(SyntaxTreeOptionsProvider? provider, CancellationT
             return provider?.IsGenerated(this, cancellationToken) switch
             {
                 null or GeneratedKind.Unknown => isGeneratedHeuristic(),
-                GeneratedKind kind => kind == GeneratedKind.Generated
+                GeneratedKind kind => kind == GeneratedKind.MarkedGenerated
             };
 
             bool isGeneratedHeuristic()
@@ -737,10 +737,10 @@ bool isGeneratedHeuristic()
                             this,
                             isComment: trivia => trivia.Kind() == SyntaxKind.SingleLineCommentTrivia || trivia.Kind() == SyntaxKind.MultiLineCommentTrivia,
                             cancellationToken: default);
-                    _lazyIsGeneratedCode = isGenerated ? GeneratedKind.Generated : GeneratedKind.NotGenerated;
+                    _lazyIsGeneratedCode = isGenerated ? GeneratedKind.MarkedGenerated : GeneratedKind.NotGenerated;
                 }
 
-                return _lazyIsGeneratedCode == GeneratedKind.Generated;
+                return _lazyIsGeneratedCode == GeneratedKind.MarkedGenerated;
             }
         }
 

src/Compilers/CSharp/Test/Semantic/Semantics/NullableReferenceTypesTests.cs

@@ -5711,10 +5711,10 @@ static void J(object x)
 #pragma warning restore CS0618
 
             var syntaxOptions = new TestSyntaxTreeOptionsProvider(
-                (source1, GeneratedKind.Generated),
+                (source1, GeneratedKind.MarkedGenerated),
                 (source2, GeneratedKind.NotGenerated),
                 (source3, GeneratedKind.Unknown),
-                (source4, GeneratedKind.Generated)
+                (source4, GeneratedKind.MarkedGenerated)
             );
 
             var comp = CreateCompilation(new[] { source1, source2, source3, source4 },

src/Compilers/Core/Portable/Compilation/GeneratedKind.cs

@@ -6,8 +6,17 @@ namespace Microsoft.CodeAnalysis
 {
     public enum GeneratedKind
     {
+        /// <summary>
+        /// Whether the <see cref="SyntaxTree"/> is automatically generated is unknown.
+        /// </summary>
         Unknown,
+        /// <summary>
+        /// The <see cref="SyntaxTree"/> is not automatically generated.
+        /// </summary>
         NotGenerated,
-        Generated
+        /// <summary>
+        /// The <see cref="SyntaxTree"/> is marked as automatically generated.
+        /// </summary>
+        MarkedGenerated
     }
 }

src/Compilers/Core/Portable/InternalUtilities/GeneratedCodeUtilities.cs

@@ -154,7 +154,7 @@ internal static GeneratedKind GetIsGeneratedCodeFromOptions(ImmutableDictionary<
             if (options.TryGetValue("generated_code", out string? optionValue) &&
                 bool.TryParse(optionValue, out var boolValue))
             {
-                return boolValue ? GeneratedKind.Generated : GeneratedKind.NotGenerated;
+                return boolValue ? GeneratedKind.MarkedGenerated : GeneratedKind.NotGenerated;
             }
 
             // Either no explicit user configuration or we don't recognize the option value.

src/Compilers/Core/Portable/PublicAPI.Unshipped.txt

@@ -16,7 +16,7 @@ Microsoft.CodeAnalysis.Diagnostics.CompilationWithAnalyzers.GetAnalysisResultAsy
 Microsoft.CodeAnalysis.Diagnostics.Telemetry.AnalyzerTelemetryInfo.AdditionalFileActionsCount.get -> int
 Microsoft.CodeAnalysis.Diagnostics.Telemetry.AnalyzerTelemetryInfo.AdditionalFileActionsCount.set -> void
 Microsoft.CodeAnalysis.GeneratedKind
-Microsoft.CodeAnalysis.GeneratedKind.Generated = 2 -> Microsoft.CodeAnalysis.GeneratedKind
+Microsoft.CodeAnalysis.GeneratedKind.MarkedGenerated = 2 -> Microsoft.CodeAnalysis.GeneratedKind
 Microsoft.CodeAnalysis.GeneratedKind.NotGenerated = 1 -> Microsoft.CodeAnalysis.GeneratedKind
 Microsoft.CodeAnalysis.GeneratedKind.Unknown = 0 -> Microsoft.CodeAnalysis.GeneratedKind
 Microsoft.CodeAnalysis.GeneratorDriver.RemoveAdditionalTexts(System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.AdditionalText> additionalTexts) -> Microsoft.CodeAnalysis.GeneratorDriver
@@ -84,4 +84,4 @@ Microsoft.CodeAnalysis.GeneratorRunResult.Generator.get -> Microsoft.CodeAnalysi
 *REMOVED*Microsoft.CodeAnalysis.SourceGeneratorContext.SyntaxReceiver.get -> Microsoft.CodeAnalysis.ISyntaxReceiver
 *REMOVED*Microsoft.CodeAnalysis.GeneratorDriver.RunFullGeneration(Microsoft.CodeAnalysis.Compilation compilation, out Microsoft.CodeAnalysis.Compilation outputCompilation, out System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.Diagnostic> diagnostics, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> Microsoft.CodeAnalysis.GeneratorDriver
 *REMOVED*Microsoft.CodeAnalysis.InitializationContext.InitializationContext() -> void
-*REMOVED*Microsoft.CodeAnalysis.SourceGeneratorContext.SourceGeneratorContext() -> void
\ No newline at end of file
+*REMOVED*Microsoft.CodeAnalysis.SourceGeneratorContext.SourceGeneratorContext() -> void