Preserve invalid friend assembly error

src/coreclr/vm/assembly.cpp

@@ -2590,12 +2590,22 @@ ReleaseHolder<FriendAssemblyDescriptor> FriendAssemblyDescriptor::CreateFriendAs
             // Create an AssemblyNameObject from the string.
             FriendAssemblyNameHolder pFriendAssemblyName;
             pFriendAssemblyName = new FriendAssemblyName_t;
-            hr = pFriendAssemblyName->InitNoThrow(displayName);
-
-            if (SUCCEEDED(hr))
+            EX_TRY
+            {
+                pFriendAssemblyName->Init(displayName);
+            }
+            EX_HOOK
             {
-                hr = pFriendAssemblyName->CheckFriendAssemblyName();
+                // Preserve the underlying reason the friend assembly name could not be
+                // parsed (e.g. a malformed identity string) as the inner exception, while
+                // reporting the assembly that declared the invalid friend.
+                Exception *pInnerException = GET_EXCEPTION();
+                if (!pInnerException->IsTransient())
+                    EEFileLoadException::Throw(pAssembly, pInnerException->GetHR(), pInnerException);
             }
+            EX_END_HOOK
+
+            hr = pFriendAssemblyName->CheckFriendAssemblyName();
 
             if (FAILED(hr))
             {

src/tests/Loader/classloader/regressions/InvalidFriendAssemblyName/InvalidFriendAssemblyName.cs

@@ -0,0 +1,34 @@
+// 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.IO;
+using System.Runtime.CompilerServices;
+using Xunit;
+
+[assembly: InternalsVisibleTo(InvalidFriendAssemblyName.InvalidAssemblyName)]
+
+public class InvalidFriendAssemblyName
+{
+    internal const string InvalidAssemblyName = "Broken,PublicKey=00240000048000009400000006020000002400005253413100040000010001002d07581667cbf8caf9786ac8d5257eb2c77eb2643a1af1bb89d4286e27a3ff5d805408c9f1a0a392d2f478ca2b9c68e43cdcdcea2d7cf0618dd8ba48858bf5fc74c7fc2af7a29f936398c0f61a2165d08ac4fcc8e8ad04e24633b7ca31a7c13f750ae75e53cea55ced97d3289fd100dbe2661a802bf8bd2acb0b6893ef3fb79c,PublicKeyToken=282361b99ded7e8e";
+
+    // Only CoreCLR surfaces the invalid friend name as a FileLoadException.
+    [ConditionalFact(typeof(TestLibrary.Utilities), nameof(TestLibrary.Utilities.IsNotMonoRuntime), nameof(TestLibrary.Utilities.IsNotNativeAot))]
+    public static void TestEntryPoint()
+    {
+        // Calling the protected Object.MemberwiseClone (defined in a different assembly) forces the
+        // runtime to run an accessibility check against this assembly, which parses its InternalsVisibleTo
+        // metadata. Because that metadata is invalid, parsing throws and surfaces the FileLoadException.
+        FileLoadException exception = Assert.Throws<FileLoadException>(() => new InvalidFriendAssemblyName().GetCopy());
+
+        // The outer exception identifies the assembly that declared the invalid friend reference.
+        Assert.Contains(nameof(InvalidFriendAssemblyName), exception.FileName, StringComparison.Ordinal);
+
+        // The inner exception preserves the real cause: the invalid friend assembly name.
+        FileLoadException inner = Assert.IsType<FileLoadException>(exception.InnerException);
+        Assert.Equal(InvalidAssemblyName, inner.FileName);
+        Assert.Contains("assembly name was invalid", inner.Message, StringComparison.OrdinalIgnoreCase);
+    }
+
+    public object GetCopy() => MemberwiseClone();
+}

src/tests/Loader/classloader/regressions/InvalidFriendAssemblyName/InvalidFriendAssemblyName.csproj

@@ -0,0 +1,6 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <ItemGroup>
+    <Compile Include="InvalidFriendAssemblyName.cs" />
+    <ProjectReference Include="$(TestLibraryProjectPath)" />
+  </ItemGroup>
+</Project>