Annotate Serilog.Settings.Configuration as not trim-compatible

Unfortunately I don't have any good news for this library. It looks like the fundamental
concept, loading arbitrary types by name from arbitrary assemblies, configured by the user
at run-time, is fundamentally incompatible with trimming and AOT.

This at least marks it as such. Supporting a feature set like the one provided
here would likely require a source generator, or build-time code generation phase.

src/Serilog.Settings.Configuration/ConfigurationLoggerConfigurationExtensions.cs

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyModel;
@@ -43,6 +44,8 @@ public static class ConfigurationLoggerConfigurationExtensions
         /// <param name="dependencyContext">The dependency context from which sink/enricher packages can be located. If not supplied, the platform
         /// default will be used.</param>
         /// <returns>An object allowing configuration to continue.</returns>
+        [RequiresUnreferencedCode(TrimWarningMessages.NotSupportedWhenTrimming)]
+        [RequiresDynamicCode(TrimWarningMessages.NotSupportedInAot)]
         public static LoggerConfiguration Configuration(
             this LoggerSettingsConfiguration settingConfiguration,
             IConfiguration configuration,
@@ -74,6 +77,8 @@ public static LoggerConfiguration Configuration(
         /// <param name="dependencyContext">The dependency context from which sink/enricher packages can be located. If not supplied, the platform
         /// default will be used.</param>
         /// <returns>An object allowing configuration to continue.</returns>
+        [RequiresUnreferencedCode(TrimWarningMessages.NotSupportedWhenTrimming)]
+        [RequiresDynamicCode(TrimWarningMessages.NotSupportedInAot)]
         public static LoggerConfiguration Configuration(
             this LoggerSettingsConfiguration settingConfiguration,
             IConfiguration configuration,
@@ -90,6 +95,8 @@ public static LoggerConfiguration Configuration(
         /// default will be used.</param>
         /// <returns>An object allowing configuration to continue.</returns>
         [Obsolete("Use ReadFrom.Configuration(IConfiguration configuration, string sectionName, DependencyContext dependencyContext) instead.")]
+        [RequiresUnreferencedCode(TrimWarningMessages.NotSupportedWhenTrimming)]
+        [RequiresDynamicCode(TrimWarningMessages.NotSupportedInAot)]
         public static LoggerConfiguration ConfigurationSection(
             this LoggerSettingsConfiguration settingConfiguration,
             IConfigurationSection configSection,
@@ -119,6 +126,8 @@ public static LoggerConfiguration ConfigurationSection(
         /// <param name="sectionName">A section name for section which contains a Serilog section.</param>
         /// <param name="configurationAssemblySource">Defines how the package identifies assemblies to scan for sinks and other types.</param>
         /// <returns>An object allowing configuration to continue.</returns>
+        [RequiresUnreferencedCode(TrimWarningMessages.NotSupportedWhenTrimming)]
+        [RequiresDynamicCode(TrimWarningMessages.NotSupportedInAot)]
         public static LoggerConfiguration Configuration(
             this LoggerSettingsConfiguration settingConfiguration,
             IConfiguration configuration,
@@ -143,6 +152,8 @@ public static LoggerConfiguration Configuration(
         /// <param name="configuration">A configuration object which contains a Serilog section.</param>
         /// <param name="configurationAssemblySource">Defines how the package identifies assemblies to scan for sinks and other types.</param>
         /// <returns>An object allowing configuration to continue.</returns>
+        [RequiresUnreferencedCode(TrimWarningMessages.NotSupportedWhenTrimming)]
+        [RequiresDynamicCode(TrimWarningMessages.NotSupportedInAot)]
         public static LoggerConfiguration Configuration(
             this LoggerSettingsConfiguration settingConfiguration,
             IConfiguration configuration,
@@ -158,6 +169,8 @@ public static LoggerConfiguration Configuration(
         /// <param name="configurationAssemblySource">Defines how the package identifies assemblies to scan for sinks and other types.</param>
         /// <returns>An object allowing configuration to continue.</returns>
         [Obsolete("Use ReadFrom.Configuration(IConfiguration configuration, string sectionName, ConfigurationAssemblySource configurationAssemblySource) instead.")]
+        [RequiresUnreferencedCode(TrimWarningMessages.NotSupportedWhenTrimming)]
+        [RequiresDynamicCode(TrimWarningMessages.NotSupportedInAot)]
         public static LoggerConfiguration ConfigurationSection(
             this LoggerSettingsConfiguration settingConfiguration,
             IConfigurationSection configSection,
@@ -179,6 +192,8 @@ public static LoggerConfiguration ConfigurationSection(
         /// <param name="sectionName">A section name for section which contains a Serilog section.</param>
         /// <param name="assemblies">A collection of assemblies that contains sinks and other types.</param>
         /// <returns>An object allowing configuration to continue.</returns>
+        [RequiresUnreferencedCode(TrimWarningMessages.NotSupportedWhenTrimming)]
+        [RequiresDynamicCode(TrimWarningMessages.NotSupportedInAot)]
         public static LoggerConfiguration Configuration(
             this LoggerSettingsConfiguration settingConfiguration,
             IConfiguration configuration,
@@ -199,6 +214,8 @@ public static LoggerConfiguration Configuration(
         /// <param name="configuration">A configuration object which contains a Serilog section.</param>
         /// <param name="assemblies">A collection of assemblies that contains sinks and other types.</param>
         /// <returns>An object allowing configuration to continue.</returns>
+        [RequiresUnreferencedCode(TrimWarningMessages.NotSupportedWhenTrimming)]
+        [RequiresDynamicCode(TrimWarningMessages.NotSupportedInAot)]
         public static LoggerConfiguration Configuration(
             this LoggerSettingsConfiguration settingConfiguration,
             IConfiguration configuration,

src/Serilog.Settings.Configuration/Serilog.Settings.Configuration.csproj

@@ -5,7 +5,7 @@
     <VersionPrefix>3.3.1</VersionPrefix>
     <LangVersion>latest</LangVersion>
     <Authors>Serilog Contributors</Authors>
-    <TargetFrameworks>netstandard2.0;net451;net461</TargetFrameworks>
+    <TargetFrameworks>net7.0;netstandard2.0;net451;net461</TargetFrameworks>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <AssemblyName>Serilog.Settings.Configuration</AssemblyName>
@@ -22,6 +22,8 @@
     <EmbedUntrackedSources>true</EmbedUntrackedSources>
     <IncludeSymbols>true</IncludeSymbols>
     <SymbolPackageFormat>snupkg</SymbolPackageFormat>
+    <IsTrimmable>true</IsTrimmable>
+    <EnableAotAnalyzer>true</EnableAotAnalyzer>
   </PropertyGroup>
 
   <ItemGroup>

src/Serilog.Settings.Configuration/Settings/Configuration/ConfigurationReader.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Reflection;
 using System.Text.RegularExpressions;
@@ -15,6 +16,8 @@
 
 namespace Serilog.Settings.Configuration
 {
+    [RequiresUnreferencedCode(TrimWarningMessages.UnboundedReflection)]
+    [RequiresDynamicCode(TrimWarningMessages.CreatesArraysOfArbitraryTypes)]
     class ConfigurationReader : IConfigurationReader
     {
         const string LevelSwitchNameRegex = @"^\${0,1}[A-Za-z]+[A-Za-z0-9]*$";
@@ -268,6 +271,8 @@ void ApplyEnrichment(LoggerConfiguration loggerConfiguration)
             }
         }
 
+        [RequiresUnreferencedCode(TrimWarningMessages.UnboundedReflection)]
+        [RequiresDynamicCode(TrimWarningMessages.CreatesArraysOfArbitraryTypes)]
         internal ILookup<string, Dictionary<string, IConfigurationArgumentValue>> GetMethodCalls(IConfigurationSection directive)
         {
             var children = directive.GetChildren().ToList();
@@ -301,6 +306,8 @@ static string GetSectionName(IConfigurationSection s)
             }
         }
 
+        [RequiresUnreferencedCode(TrimWarningMessages.UnboundedReflection)]
+        [RequiresDynamicCode(TrimWarningMessages.CreatesArraysOfArbitraryTypes)]
         internal static IConfigurationArgumentValue GetArgumentValue(IConfigurationSection argumentSection, IReadOnlyCollection<Assembly> configurationAssemblies)
         {
             IConfigurationArgumentValue argumentValue;

src/Serilog.Settings.Configuration/Settings/Configuration/ObjectArgumentValue.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
@@ -10,6 +11,8 @@
 
 namespace Serilog.Settings.Configuration
 {
+    [RequiresUnreferencedCode(TrimWarningMessages.UnboundedReflection)]
+    [RequiresDynamicCode(TrimWarningMessages.CreatesArraysOfArbitraryTypes)]
     class ObjectArgumentValue : IConfigurationArgumentValue
     {
         readonly IConfigurationSection _section;
@@ -59,6 +62,7 @@ public object ConvertTo(Type toType, ResolutionContext resolutionContext)
             // MS Config binding can work with a limited set of primitive types and collections
             return _section.Get(toType);
 
+            [RequiresDynamicCode(TrimWarningMessages.CreatesArraysOfArbitraryTypes)]
             object CreateArray()
             {
                 var arrayElementType = toType.GetElementType()!;

src/Serilog.Settings.Configuration/Settings/Configuration/RequiresDynamicCode.cs

@@ -0,0 +1,16 @@
+#if !NET6_0_OR_GREATER
+
+namespace System.Diagnostics.CodeAnalysis
+{
+    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Constructor | AttributeTargets.Method, Inherited = false)]
+    internal sealed class RequiresDynamicCodeAttribute : Attribute
+    {
+        public RequiresDynamicCodeAttribute(string message)
+        {
+            Message = message;
+        }
+
+        public string Message { get; }
+    }
+}
+#endif

src/Serilog.Settings.Configuration/Settings/Configuration/RequiresUnreferencedCodeAttribute.cs

@@ -0,0 +1,16 @@
+
+#if !NET5_0_OR_GREATER
+namespace System.Diagnostics.CodeAnalysis
+{
+    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Constructor | AttributeTargets.Method, Inherited = false)]
+    internal sealed class RequiresUnreferencedCodeAttribute : Attribute
+    {
+        public RequiresUnreferencedCodeAttribute(string message)
+        {
+            Message = message;
+        }
+
+        public string Message { get; }
+    }
+}
+#endif

src/Serilog.Settings.Configuration/Settings/Configuration/StringArgumentValue.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Reflection;
 using System.Text.RegularExpressions;
@@ -8,6 +9,7 @@
 
 namespace Serilog.Settings.Configuration
 {
+    [RequiresUnreferencedCode(TrimWarningMessages.UnboundedReflection)]
     class StringArgumentValue : IConfigurationArgumentValue
     {
         readonly string _providedValue;

src/Serilog.Settings.Configuration/TrimWarningMessages.cs

@@ -0,0 +1,13 @@
+
+using System.Data;
+
+namespace Serilog
+{
+    internal static class TrimWarningMessages
+    {
+        public const string NotSupportedWhenTrimming = "Automatic configuration is not supported when trimming.";
+        public const string NotSupportedInAot = "Automatic configuration is not supported when AOT compiling.";
+        public const string UnboundedReflection = "Uses unbounded reflection to load types";
+        public const string CreatesArraysOfArbitraryTypes = "Creates arrays of arbitrary types";
+    }
+}