AssemblyNameInfo.FullName should contain PublicKey, fixes #102051 (#105649)

Author: adamsitnik

src/libraries/Common/src/System/Reflection/AssemblyNameFormatter.cs

@@ -10,7 +10,7 @@ namespace System.Reflection
 {
     internal static class AssemblyNameFormatter
     {
-        public static string ComputeDisplayName(string name, Version? version, string? cultureName, byte[]? pkt, AssemblyNameFlags flags = 0, AssemblyContentType contentType = 0)
+        public static string ComputeDisplayName(string name, Version? version, string? cultureName, byte[]? pkt, AssemblyNameFlags flags = 0, AssemblyContentType contentType = 0, byte[]? pk = null)
         {
             const int PUBLIC_KEY_TOKEN_LEN = 8;
             Debug.Assert(name.Length != 0);
@@ -57,19 +57,28 @@ public static string ComputeDisplayName(string name, Version? version, string? c
                 vsb.AppendQuoted(cultureName);
             }
 
-            if (pkt != null)
+            byte[]? keyOrToken = pkt ?? pk;
+            if (keyOrToken != null)
             {
-                if (pkt.Length > PUBLIC_KEY_TOKEN_LEN)
-                    throw new ArgumentException();
+                if (pkt != null)
+                {
+                    if (pkt.Length > PUBLIC_KEY_TOKEN_LEN)
+                        throw new ArgumentException();
+
+                    vsb.Append(", PublicKeyToken=");
+                }
+                else
+                {
+                    vsb.Append(", PublicKey=");
+                }
 
-                vsb.Append(", PublicKeyToken=");
-                if (pkt.Length == 0)
+                if (keyOrToken.Length == 0)
                 {
                     vsb.Append("null");
                 }
                 else
                 {
-                    HexConverter.EncodeToUtf16(pkt, vsb.AppendSpan(pkt.Length * 2), HexConverter.Casing.Lower);
+                    HexConverter.EncodeToUtf16(keyOrToken, vsb.AppendSpan(keyOrToken.Length * 2), HexConverter.Casing.Lower);
                 }
             }
 

src/libraries/System.Reflection.Metadata/src/System/Reflection/Metadata/AssemblyNameInfo.cs

@@ -108,16 +108,20 @@ public string FullName
             {
                 if (_fullName is null)
                 {
-                    byte[]? publicKeyToken = ((Flags & AssemblyNameFlags.PublicKey) != 0) ? null :
+                    bool isPublicKey = (Flags & AssemblyNameFlags.PublicKey) != 0;
+
+                    byte[]? publicKeyOrToken =
 #if SYSTEM_PRIVATE_CORELIB
                     PublicKeyOrToken;
 #elif NET8_0_OR_GREATER
                     !PublicKeyOrToken.IsDefault ? Runtime.InteropServices.ImmutableCollectionsMarshal.AsArray(PublicKeyOrToken) : null;
 #else
                     !PublicKeyOrToken.IsDefault ? PublicKeyOrToken.ToArray() : null;
 #endif
-                    _fullName = AssemblyNameFormatter.ComputeDisplayName(Name, Version, CultureName, publicKeyToken,
-                        ExtractAssemblyNameFlags(_flags), ExtractAssemblyContentType(_flags));
+                    _fullName = AssemblyNameFormatter.ComputeDisplayName(Name, Version, CultureName,
+                        pkt: isPublicKey ? null : publicKeyOrToken,
+                        ExtractAssemblyNameFlags(_flags), ExtractAssemblyContentType(_flags),
+                        pk: isPublicKey ? publicKeyOrToken : null);
                 }
 
                 return _fullName;

src/libraries/System.Reflection.Metadata/tests/Metadata/AssemblyNameInfoTests.cs

@@ -21,6 +21,18 @@ public void WithPublicTokenKey(string fullName)
             Roundtrip(assemblyName);
         }
 
+        [Theory]
+        [InlineData("System.IO.Pipelines.Tests, PublicKey=00240000048000009400000006020000002400005253413100040000010001004b86c4cb78549b34bab61a3b1800e23bfeb5b3ec390074041536a7e3cbd97f5f04cf0f857155a8928eaa29ebfd11cfbbad3ba70efea7bda3226c6a8d370a4cd303f714486b6ebc225985a638471e6ef571cc92a4613c00b8fa65d61ccee0cbe5f36330c9a01f4183559f1bef24cc2917c6d913e3a541333a1d05d9bed22b38cb")]
+        [InlineData("System.IO.Pipelines.Tests, PublicKey=null")]
+        public void FullNameContainsPublicKey(string withPublicKey)
+        {
+            AssemblyNameInfo assemblyNameInfo = AssemblyNameInfo.Parse(withPublicKey.AsSpan());
+            Assert.Equal(withPublicKey, assemblyNameInfo.FullName);
+
+            AssemblyNameInfo roundTrip = AssemblyNameInfo.Parse(assemblyNameInfo.FullName.AsSpan());
+            Assert.Equal(withPublicKey, roundTrip.FullName);
+        }
+
         [Fact]
         public void NoPublicKeyOrToken()
         {