Resolve ILLink warnings in System.Diagnostics.DiagnosticSource (Round 1)

Contributes to #45623

Author: eerhardt

src/libraries/System.Diagnostics.DiagnosticSource/src/ILLink/ILLink.Suppressions.xml

@@ -7,11 +7,5 @@
       <property name="Scope">member</property>
       <property name="Target">M:System.Diagnostics.DiagnosticSourceEventSource.FilterAndTransform.MakeImplicitTransforms(System.Type)</property>
     </attribute>
-    <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
-      <argument>ILLink</argument>
-      <argument>IL2070</argument>
-      <property name="Scope">member</property>
-      <property name="Target">M:System.Diagnostics.DiagnosticSourceEventSource.TransformSpec.PropertySpec.PropertyFetch.FetcherForProperty(System.Type,System.String)</property>
-    </attribute>
   </assembly>
-</linker>
+</linker>

src/libraries/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <CLSCompliant>false</CLSCompliant>
@@ -29,8 +29,6 @@
     <None Include="DiagnosticSourceUsersGuide.md" />
   </ItemGroup>
   <ItemGroup Condition="$([MSBuild]::GetTargetFrameworkIdentifier('$(TargetFramework)')) != '.NETCoreApp'">
-    <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\DynamicDependencyAttribute.cs" />
-    <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\DynamicallyAccessedMemberTypes.cs" />
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\UnconditionalSuppressMessageAttribute.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)' != 'netstandard1.1'">

src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/DiagnosticSourceEventSource.cs

@@ -1331,9 +1331,6 @@ public PropertyFetch(Type? type)
                     /// <summary>
                     /// Create a property fetcher for a propertyName
                     /// </summary>
-                    [DynamicDependency("#ctor(System.Type)", typeof(EnumeratePropertyFetch<>))]
-                    [DynamicDependency("#ctor(System.Type,System.Reflection.PropertyInfo)", typeof(RefTypedFetchProperty<,>))]
-                    [DynamicDependency("#ctor(System.Type,System.Reflection.PropertyInfo)", typeof(ValueTypedFetchProperty<,>))]
                     public static PropertyFetch FetcherForProperty(Type? type, string propertyName)
                     {
                         if (propertyName == null)
@@ -1382,10 +1379,14 @@ public static PropertyFetch FetcherForProperty(Type? type, string propertyName)
                         }
                         else
                         {
-                            PropertyInfo? propertyInfo = typeInfo.GetDeclaredProperty(propertyName);
+                            [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2070:RequiresUnreferencedCode",
+                                Justification = "If the property is trimmed, a message gets logged to inform the user.")]
+                            static PropertyInfo? GetProperty(TypeInfo type, string name) => type.GetDeclaredProperty(name);
+
+                            PropertyInfo? propertyInfo = GetProperty(typeInfo, propertyName);
                             if (propertyInfo == null)
                             {
-                                Logger.Message($"Property {propertyName} not found on {type}");
+                                Logger.Message($"Property {propertyName} not found on {type}. Ensure the name is spelled correctly. If you published the application with PublishTrimmed=true, ensure the property was not trimmed away.");
                                 return new PropertyFetch(type);
                             }
                             // Delegate creation below is incompatible with static properties.