ifdef

src/libraries/Common/src/Roslyn/Hash.cs

@@ -18,6 +18,8 @@ internal static int Combine(int newKey, int currentKey)
             return unchecked((currentKey * (int)0xA5555529) + newKey);
         }
 
+#if false
+
         internal static int Combine(bool newKeyPart, int currentKey)
         {
             return Combine(currentKey, newKeyPart ? 1 : 0);
@@ -373,5 +375,7 @@ internal static int CombineFNVHash(int hashCode, char ch)
         {
             return unchecked((hashCode ^ ch) * Hash.FnvPrime);
         }
+
+#endif
     }
 }

src/libraries/Common/src/Roslyn/SyntaxValueProvider_ForAttributeWithMetadataName.cs

@@ -12,6 +12,7 @@
 using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.DotnetRuntime.Extensions;
+
 internal readonly struct GeneratorAttributeSyntaxContext
 {
     /// <summary>

src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.cs

@@ -16,6 +16,7 @@
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Text;
+using Microsoft.CodeAnalysis.DotnetRuntime.Extensions;
 
 [assembly: System.Resources.NeutralResourcesLanguage("en-us")]
 
@@ -51,7 +52,11 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
                 context.SyntaxProvider
 
                 // Find all MethodDeclarationSyntax nodes attributed with RegexGenerator and gather the required information.
-                .CreateSyntaxProvider(IsSyntaxTargetForGeneration, GetSemanticTargetForGeneration)
+                .ForAttributeWithMetadataName(
+                    context,
+                    RegexGeneratorAttributeName,
+                    (n, c) => n is MethodDeclarationSyntax,
+                    GetSemanticTargetForGeneration)
                 .Where(static m => m is not null)
 
                 // Generate the RunnerFactory for each regex, if possible.  This is where the bulk of the implementation occurs.