Remove reflection from FrameworkDescription (dotnet#102164)

* Remove reflection from FrameworkDescription

* Switch to source gen

* Address CR feedback

* Update src/libraries/System.Private.CoreLib/gen/ProductVersionInfoGenerator.cs

Co-authored-by: Jan Kotas <jkotas@microsoft.com>

---------

Co-authored-by: Jan Kotas <jkotas@microsoft.com>

src/libraries/System.Private.CoreLib/gen/ProductVersionInfoGenerator.cs

@@ -0,0 +1,54 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Reflection;
+using Microsoft.CodeAnalysis;
+
+namespace Generators
+{
+    [Generator]
+    public partial class ProductVersionInfoGenerator : IIncrementalGenerator
+    {
+        public void Initialize(IncrementalGeneratorInitializationContext context)
+        {
+            context.RegisterPostInitializationOutput(ctx =>
+            {
+                string? informationalVersion = typeof(ProductVersionInfoGenerator).Assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>()?.InformationalVersion;
+
+                // strip semver metadata (git hash) followed by + sign
+                string? productVersion = informationalVersion?.Split('+')?[0];
+
+                if (string.IsNullOrEmpty(productVersion))
+                    throw new InvalidOperationException($"Unable to obtain product version at build-time.");
+
+                // strip semver prerelease label followed by - sign for Environment.Version
+                Version versionObject = Version.Parse(productVersion.Split('-')[0]);
+
+                ctx.AddSource("ProductVersionInfo.g.cs", $@"// <auto-generated/>
+
+namespace System
+{{
+    public static partial class Environment
+    {{
+        /// <summary>
+        /// Gets a version consisting of the major, minor, build, and revision numbers of the common language runtime.
+        /// </summary>
+        public static Version Version => new Version({versionObject.ToString().Replace(".", ", ")});
+    }}
+}}
+
+namespace System.Runtime.InteropServices
+{{
+    public static partial class RuntimeInformation
+    {{
+        /// <summary>
+        /// Gets the name of the .NET installation on which an app is running.
+        /// </summary>
+        public static string FrameworkDescription => "".NET {productVersion}"";
+    }}
+}}");
+            });
+        }
+    }
+}

src/libraries/System.Private.CoreLib/gen/System.Private.CoreLib.Generators.csproj

@@ -5,6 +5,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <Compile Include="ProductVersionInfoGenerator.cs" />
     <Compile Include="EventSourceGenerator.cs" />
     <Compile Include="EventSourceGenerator.Emitter.cs" />
     <Compile Include="EventSourceGenerator.Parser.cs" />
@@ -20,4 +21,5 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" PrivateAssets="all" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" />
   </ItemGroup>
+
 </Project>

src/libraries/System.Private.CoreLib/src/System/Environment.cs

@@ -3,7 +3,6 @@
 
 using System.Collections;
 using System.Diagnostics;
-using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Threading;
 
@@ -201,24 +200,6 @@ public static OperatingSystem OSVersion
             }
         }
 
-        public static Version Version
-        {
-            get
-            {
-                string? versionString = typeof(object).Assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>()?.InformationalVersion;
-
-                ReadOnlySpan<char> versionSpan = versionString.AsSpan();
-
-                // Strip optional suffixes
-                int separatorIndex = versionSpan.IndexOfAny('-', '+', ' ');
-                if (separatorIndex >= 0)
-                    versionSpan = versionSpan.Slice(0, separatorIndex);
-
-                // Return zeros rather then failing if the version string fails to parse
-                return Version.TryParse(versionSpan, out Version? version) ? version : new Version();
-            }
-        }
-
         public static string StackTrace
         {
             [MethodImpl(MethodImplOptions.NoInlining)] // Prevent inlining from affecting where the stacktrace starts

src/libraries/System.Private.CoreLib/src/System/Runtime/InteropServices/RuntimeInformation.cs

@@ -1,38 +1,12 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.Reflection;
-
 namespace System.Runtime.InteropServices
 {
     public static partial class RuntimeInformation
     {
-        private const string FrameworkName = ".NET";
-        private static string? s_frameworkDescription;
         private static string? s_runtimeIdentifier;
 
-        public static string FrameworkDescription
-        {
-            get
-            {
-                if (s_frameworkDescription == null)
-                {
-                    ReadOnlySpan<char> versionString = typeof(object).Assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>()?.InformationalVersion;
-
-                    // Strip the git hash if there is one
-                    int plusIndex = versionString.IndexOf('+');
-                    if (plusIndex >= 0)
-                    {
-                        versionString = versionString.Slice(0, plusIndex);
-                    }
-
-                    s_frameworkDescription = !versionString.Trim().IsEmpty ? $"{FrameworkName} {versionString}" : FrameworkName;
-                }
-
-                return s_frameworkDescription;
-            }
-        }
-
         /// <summary>
         /// Returns an opaque string that identifies the platform on which an app is running.
         /// </summary>