[SDK] Fix circular reference issue in TracerProvider buildup

src/OpenTelemetry/Internal/Builder/ProviderBuilderServiceCollectionExtensions.cs

@@ -41,6 +41,7 @@ public static IServiceCollection AddOpenTelemetryTracerProviderBuilderServices(t
         services.AddOpenTelemetryProviderBuilderServices();
 
         services.RegisterOptionsFactory(configuration => new ExportActivityProcessorOptions(configuration));
+        services.TryAddSingleton<TracerProviderBuilderState>();
 
         return services;
     }

src/OpenTelemetry/Trace/Builder/TracerProviderBuilderBase.cs

@@ -45,8 +45,9 @@ internal TracerProviderBuilderBase(TracerProviderBuilderState state)
             this.State = state;
         }
 
-        // This ctor is for AddOpenTelemetryTracing scenario where the builder
-        // is bound to an external service collection.
+        // This ctor is for ConfigureOpenTelemetryTracing +
+        // AddOpenTelemetryTracing scenarios where the builder is bound to an
+        // external service collection.
         internal TracerProviderBuilderBase(IServiceCollection services)
         {
             Guard.ThrowIfNull(services);
@@ -65,6 +66,8 @@ protected TracerProviderBuilderBase()
             var services = new ServiceCollection();
 
             services.AddOpenTelemetryTracerProviderBuilderServices();
+            services.AddSingleton<TracerProvider>(
+                sp => throw new NotSupportedException("External TracerProvider created through Sdk.CreateTracerProviderBuilder cannot be accessed using service provider."));
 
             this.services = services;
             this.ownsServices = true;

src/OpenTelemetry/Trace/Builder/TracerProviderBuilderState.cs

@@ -38,6 +38,7 @@ internal sealed class TracerProviderBuilderState
         internal Sampler? Sampler;
         internal bool SetErrorStatusOnException;
 
+        private bool hasEnteredBuildPhase;
         private TracerProviderBuilderSdk? builder;
 
         public TracerProviderBuilderState(IServiceProvider serviceProvider)
@@ -49,6 +50,16 @@ public TracerProviderBuilderState(IServiceProvider serviceProvider)
 
         public TracerProviderBuilderSdk Builder => this.builder ??= new TracerProviderBuilderSdk(this);
 
+        public void CheckForCircularBuild()
+        {
+            if (this.hasEnteredBuildPhase)
+            {
+                throw new NotSupportedException("TracerProvider cannot be accessed while build is executing.");
+            }
+
+            this.hasEnteredBuildPhase = true;
+        }
+
         public void AddInstrumentation(
             string instrumentationName,
             string instrumentationVersion,

src/OpenTelemetry/Trace/TracerProviderSdk.cs

@@ -22,6 +22,7 @@
 using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Text;
+using Microsoft.Extensions.DependencyInjection;
 using OpenTelemetry.Internal;
 using OpenTelemetry.Resources;
 
@@ -47,6 +48,9 @@ internal TracerProviderSdk(
         {
             Debug.Assert(serviceProvider != null, "serviceProvider was null");
 
+            var state = serviceProvider!.GetRequiredService<TracerProviderBuilderState>();
+            state.CheckForCircularBuild();
+
             this.ServiceProvider = serviceProvider!;
 
             if (ownsServiceProvider)
@@ -57,8 +61,6 @@ internal TracerProviderSdk(
 
             OpenTelemetrySdkEventSource.Log.TracerProviderSdkEvent("Building TracerProvider.");
 
-            var state = new TracerProviderBuilderState(serviceProvider!);
-
             TracerProviderBuilderServiceCollectionHelper.InvokeRegisteredConfigureStateCallbacks(
                 serviceProvider!,
                 state);

test/OpenTelemetry.Tests/Trace/TracerProviderBuilderExtensionsTest.cs

@@ -455,6 +455,56 @@ public void ConfigureBuilderIConfigurationModifiableTest()
             Assert.True(configureBuilderCalled);
         }
 
+        [Theory]
+        [InlineData(true)]
+        [InlineData(false)]
+        public void TracerProviderNestedResolutionUsingBuilderTest(bool callNestedConfigure)
+        {
+            bool innerTestExecuted = false;
+
+            using var provider = Sdk.CreateTracerProviderBuilder()
+                .ConfigureServices(services =>
+                {
+                    if (callNestedConfigure)
+                    {
+                        services.ConfigureOpenTelemetryTracing();
+                    }
+                })
+                .ConfigureBuilder((sp, builder) =>
+                {
+                    innerTestExecuted = true;
+                    Assert.Throws<NotSupportedException>(() => sp.GetService<TracerProvider>());
+                })
+                .Build();
+
+            Assert.True(innerTestExecuted);
+
+            Assert.Throws<NotSupportedException>(() => provider.GetServiceProvider()?.GetService<TracerProvider>());
+        }
+
+        [Fact]
+        public void TracerProviderNestedResolutionUsingConfigureTest()
+        {
+            bool innerTestExecuted = false;
+
+            var serviceCollection = new ServiceCollection();
+
+            serviceCollection.ConfigureOpenTelemetryTracing(builder =>
+            {
+                builder.ConfigureBuilder((sp, builder) =>
+                {
+                    innerTestExecuted = true;
+                    Assert.Throws<NotSupportedException>(() => sp.GetService<TracerProvider>());
+                });
+            });
+
+            using var serviceProvider = serviceCollection.BuildServiceProvider();
+
+            var resolvedProvider = serviceProvider.GetRequiredService<TracerProvider>();
+
+            Assert.True(innerTestExecuted);
+        }
+
         private static void RunBuilderServiceLifecycleTest(
             TracerProviderBuilder builder,
             Func<TracerProviderSdk> buildFunc,