[release/6.0] SyntaxValueProvider: avoid performance issue with syntax list containing many items

src/libraries/Common/src/Roslyn/SyntaxValueProvider_ForAttributeWithSimpleName.cs

@@ -334,7 +334,16 @@ void processMember(
                         // For any other node, just keep recursing deeper to see if we can find an attribute. Note: we cannot
                         // terminate the search anywhere as attributes may be found on things like local functions, and that
                         // means having to dive deep into statements and expressions.
-                        foreach (var child in node.ChildNodesAndTokens().Reverse())
+                        var childNodesAndTokens = node.ChildNodesAndTokens();
+
+                        // Avoid performance issue in ChildSyntaxList when iterating the child list in reverse
+                        // (see https://github.com/dotnet/roslyn/issues/66475) by iterating forward first to
+                        // ensure child nodes are realized.
+                        foreach (var childNode in childNodesAndTokens)
+                        {
+                        }
+
+                        foreach (var child in childNodesAndTokens.Reverse())
                         {
                             if (child.IsNode)
                                 nodeStack.Append(child.AsNode()!);

src/libraries/Microsoft.Extensions.Logging.Abstractions/src/Microsoft.Extensions.Logging.Abstractions.csproj

@@ -17,7 +17,8 @@ Microsoft.Extensions.Logging.LogLevel
 Microsoft.Extensions.Logging.Logger<T>
 Microsoft.Extensions.Logging.LoggerMessage
 Microsoft.Extensions.Logging.Abstractions.NullLogger</PackageDescription>
-    <ServicingVersion>3</ServicingVersion>
+    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
+    <ServicingVersion>4</ServicingVersion>
   </PropertyGroup>
 
   <ItemGroup>

src/libraries/Microsoft.Extensions.Logging.Abstractions/tests/Microsoft.Extensions.Logging.Generators.Tests/LoggerMessageGeneratorParserTests.cs

@@ -742,6 +742,40 @@ partial class C
             Assert.Equal(21, generatedSources[0].SourceText.Lines.Count);
         }
 
+        [Fact]
+        public static void SyntaxListWithManyItems()
+        {
+            const int nItems = 200000;
+            var builder = new System.Text.StringBuilder();
+            builder.AppendLine(
+                @"
+                using Microsoft.Extensions.Logging;
+                class Program
+                {
+                    [LoggerMessage(EventId = 1, Level = LogLevel.Debug, Message = ""M1"")]
+                    static partial void M1(ILogger logger)
+                    {
+                ");
+            builder.AppendLine("    int[] values = new[] { ");
+            for (int i = 0; i < nItems; i++)
+            {
+                builder.Append("0, ");
+            }
+            builder.AppendLine("};");
+            builder.AppendLine("}");
+            builder.AppendLine("}");
+
+            string source = builder.ToString();
+            Compilation compilation = CompilationHelper.CreateCompilation(source);
+            LoggerMessageGenerator generator = new LoggerMessageGenerator();
+
+            (ImmutableArray<Diagnostic> diagnostics, _) =
+                RoslynTestUtils.RunGenerator(compilation, generator);
+
+            Assert.Single(diagnostics);
+            Assert.Equal(DiagnosticDescriptors.LoggingMethodHasBody.Id, diagnostics[0].Id);
+        }
+
         private static async Task<IReadOnlyList<Diagnostic>> RunGenerator(
             string code,
             bool wrap = true,

src/libraries/System.Text.Json/src/System.Text.Json.csproj

@@ -9,7 +9,8 @@
     <Nullable>enable</Nullable>
     <IncludeInternalObsoleteAttribute>true</IncludeInternalObsoleteAttribute>
     <IsPackable>true</IsPackable>
-    <ServicingVersion>7</ServicingVersion>
+    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
+    <ServicingVersion>8</ServicingVersion>
     <PackageDescription>Provides high-performance and low-allocating types that serialize objects to JavaScript Object Notation (JSON) text and deserialize JSON text to objects, with UTF-8 support built-in. Also provides types to read and write JSON text encoded as UTF-8, and to create an in-memory document object model (DOM), that is read-only, for random access of the JSON elements within a structured view of the data.
 
 Commonly Used Types: