Polyfill clean up and source package organization

src/Build/Microsoft.Build.csproj

@@ -38,14 +38,36 @@
 
     <PackageReference Include="Microsoft.IO.Redist" Condition="'$(FeatureMSIORedist)' == 'true'" />
 
-    <PackageReference Include="Microsoft.CodeAnalysis.Collections" PrivateAssets="all" />
-    <PackageReference Include="Microsoft.CodeAnalysis.PooledObjects" PrivateAssets="all" />
     <PackageReference Include="Microsoft.BuildXL.Processes" Condition="'$(FeatureReportFileAccesses)' == 'true'" PrivateAssets="all" />
     <!-- Remove the direct NETStandard.Library dependency when Microsoft.BuildXL.Processes stops bringing in netstandard1.x dependencies
          or when a .NET 10 SDK is used (NuGet Package Pruning eliminates netstandard1.x dependencies). -->
     <PackageReference Include="NETStandard.Library" VersionOverride="2.0.3" PrivateAssets="all" Condition="'$(FeatureReportFileAccesses)' == 'true'" />
   </ItemGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Microsoft.CodeAnalysis.Collections" PrivateAssets="all" />
+
+    <!-- Display files included by the Microsoft.CodeAnalysis.Collections source package in a 'SourcePackages\Collections' folder -->
+    <Content Update="@(Content)">
+      <Link Condition="'%(NuGetPackageId)' == 'Microsoft.CodeAnalysis.Collections'">SourcePackages\Collections\%(Link)</Link>
+    </Content>
+    <Compile Update="@(Compile)">
+      <Link Condition="'%(NuGetPackageId)' == 'Microsoft.CodeAnalysis.Collections'">SourcePackages\Collections\%(Link)</Link>
+    </Compile>
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.CodeAnalysis.PooledObjects" PrivateAssets="all" />
+
+    <!-- Display files included by the Microsoft.CodeAnalysis.PooledObjects source package in a 'SourcePackages\PooledObjects' folder -->
+    <Content Update="@(Content)">
+      <Link Condition="'%(NuGetPackageId)' == 'Microsoft.CodeAnalysis.PooledObjects'">SourcePackages\PooledObjects\%(Link)</Link>
+    </Content>
+    <Compile Update="@(Compile)">
+      <Link Condition="'%(NuGetPackageId)' == 'Microsoft.CodeAnalysis.PooledObjects'">SourcePackages\PooledObjects\%(Link)</Link>
+    </Compile>
+  </ItemGroup>
+
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework' and '$(DotNetBuildSourceOnly)' != 'true'">
     <PackageReference Include="Microsoft.VisualStudio.Setup.Configuration.Interop" PrivateAssets="all" />
   </ItemGroup>

src/Framework/BuildErrorEventArgs.cs

@@ -2,9 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using System.IO;
 using Microsoft.Build.Shared;
 

src/Framework/BuildMessageEventArgs.cs

@@ -2,9 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using System.IO;
 using System.Runtime.Serialization;
 using Microsoft.Build.Shared;

src/Framework/BuildWarningEventArgs.cs

@@ -2,9 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using System.IO;
 using Microsoft.Build.Shared;
 

src/Framework/CriticalBuildMessageEventArgs.cs

@@ -2,9 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 
 #nullable disable
 

src/Framework/CustomBuildEventArgs.cs

@@ -2,9 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 
 #nullable disable
 

src/Framework/ExtendedBuildErrorEventArgs.cs

@@ -3,9 +3,7 @@
 
 using System;
 using System.Collections.Generic;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using System.IO;
 using Microsoft.Build.Shared;
 

src/Framework/ExtendedBuildWarningEventArgs.cs

@@ -3,9 +3,7 @@
 
 using System;
 using System.Collections.Generic;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using System.IO;
 using Microsoft.Build.Shared;
 

src/Framework/LazyFormattedBuildEventArgs.cs

@@ -2,9 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using System.Globalization;
 using System.IO;
 

src/Framework/Microsoft.Build.Framework.csproj

@@ -16,6 +16,14 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.CodeAnalysis.Contracts" PrivateAssets="all" />
+
+    <!-- Display files included by the Microsoft.CodeAnalysis.Contracts source package in a 'SourcePackages\Contracts' folder -->
+    <Content Update="@(Content)">
+      <Link Condition="'%(NuGetPackageId)' == 'Microsoft.CodeAnalysis.Contracts'">SourcePackages\Contracts\%(Link)</Link>
+    </Content>
+    <Compile Update="@(Compile)">
+      <Link Condition="'%(NuGetPackageId)' == 'Microsoft.CodeAnalysis.Contracts'">SourcePackages\Contracts\%(Link)</Link>
+    </Compile>
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">

src/Framework/Polyfills/CallerArgumentExpressionAttribute.cs

@@ -1,9 +1,17 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+#if NETCOREAPP3_0_OR_GREATER
+
+using System.Runtime.CompilerServices;
+
+// This is a supporting forwarder for an internal polyfill API
+[assembly: TypeForwardedTo(typeof(CallerArgumentExpressionAttribute))]
+
+#else
+
 namespace System.Runtime.CompilerServices;
 
-#if !NET
 [AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = false)]
 internal sealed class CallerArgumentExpressionAttribute : Attribute
 {
@@ -14,4 +22,5 @@ public CallerArgumentExpressionAttribute(string parameterName)
 
     public string ParameterName { get; }
 }
+
 #endif

src/Framework/Polyfills/StringSyntaxAttribute.cs

@@ -1,9 +1,16 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#if !NET
+#if NET7_0_OR_GREATER
 
-using System;
+using System.Runtime.CompilerServices;
+
+// This is a supporting forwarder for an internal polyfill API
+[assembly: TypeForwardedTo(typeof(System.Diagnostics.CodeAnalysis.StringSyntaxAttribute))]
+
+#else
+
+namespace System.Diagnostics.CodeAnalysis;
 
 [AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = false, Inherited = false)]
 internal sealed class StringSyntaxAttribute : Attribute
@@ -67,4 +74,5 @@ public StringSyntaxAttribute(string syntax, params object?[] arguments)
     /// <summary>The syntax identifier for strings containing XML.</summary>
     public const string Xml = nameof(Xml);
 }
+
 #endif

src/Framework/ProjectImportedEventArgs.cs

@@ -2,9 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using System.IO;
 using Microsoft.Build.Shared;
 

src/Framework/TargetSkippedEventArgs.cs

@@ -2,9 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using System.IO;
 using Microsoft.Build.Shared;
 

src/Shared/TaskLoggingHelper.cs

@@ -4,9 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using System.Globalization;
 using System.IO;
 using System.Resources;

src/Tasks/Error.cs

@@ -3,9 +3,7 @@
 
 #nullable disable
 
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using Microsoft.Build.Framework;
 
 namespace Microsoft.Build.Tasks

src/Tasks/Exec.cs

@@ -3,9 +3,7 @@
 
 using System;
 using System.Collections.Generic;
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using System.IO;
 using System.Text;
 using System.Text.RegularExpressions;

src/Tasks/Warning.cs

@@ -3,9 +3,7 @@
 
 #nullable disable
 
-#if NET
 using System.Diagnostics.CodeAnalysis;
-#endif
 using Microsoft.Build.Framework;
 
 namespace Microsoft.Build.Tasks