Add regression tests for #2441

After discussing the matter, @agocke, @tmat and I have concluded that the
implementation in EETypeNameDecoder will never be affected by the bug the
compiler was seeing.  However, we still felt it would be worthwhile to
make the implementations consistent.  There is, however, no test, since
the behavior is unchanged.

I added some using/import tests since they use the compiler implementation
(which has already been fixed).

Fixes #2441

src/ExpressionEvaluator/CSharp/Source/ExpressionCompiler/EETypeNameDecoder.cs

@@ -20,9 +20,8 @@ internal sealed class EETypeNameDecoder : TypeNameDecoder<PEModuleSymbol, TypeSy
 
         protected override int GetIndexOfReferencedAssembly(AssemblyIdentity identity)
         {
-            var assemblies = this.GetAssemblies();
             // Find assembly matching identity.
-            int index = assemblies.IndexOf((assembly, id) => id.Equals(assembly.Identity), identity);
+            int index = this.Module.GetReferencedAssemblies().IndexOf(identity);
             if (index >= 0)
             {
                 return index;
@@ -31,6 +30,7 @@ protected override int GetIndexOfReferencedAssembly(AssemblyIdentity identity)
             {
                 // Find placeholder Windows.winmd assembly (created
                 // in MetadataUtilities.MakeAssemblyReferences).
+                var assemblies = this.Module.GetReferencedAssemblySymbols();
                 index = assemblies.IndexOf((assembly, unused) => assembly.Identity.IsWindowsRuntime(), (object)null);
                 if (index >= 0)
                 {
@@ -58,7 +58,7 @@ protected override TypeSymbol LookupNestedTypeDefSymbol(TypeSymbol container, re
 
         protected override TypeSymbol LookupTopLevelTypeDefSymbol(int referencedAssemblyIndex, ref MetadataTypeName emittedName)
         {
-            var assembly = this.GetAssemblies()[referencedAssemblyIndex];
+            var assembly = this.Module.GetReferencedAssemblySymbols()[referencedAssemblyIndex];
             return assembly.LookupTopLevelMetadataType(ref emittedName, digThroughForwardedTypes: true);
         }
 
@@ -67,14 +67,11 @@ protected override TypeSymbol LookupTopLevelTypeDefSymbol(ref MetadataTypeName e
             return this.moduleSymbol.LookupTopLevelMetadataType(ref emittedName, out isNoPiaLocalType);
         }
 
-        private ImmutableArray<AssemblySymbol> GetAssemblies()
-        {
-            return _compilation.Assembly.Modules.Single().GetReferencedAssemblySymbols();
-        }
-
         private static AssemblyIdentity GetComponentAssemblyIdentity(ModuleSymbol module)
         {
             return ((PEModuleSymbol)module).Module.ReadAssemblyIdentityOrThrow();
         }
+
+        private ModuleSymbol Module => _compilation.Assembly.Modules.Single();
     }
 }

src/ExpressionEvaluator/CSharp/Test/ExpressionCompiler/UsingDebugInfoTests.cs

@@ -8,8 +8,11 @@
 using System.Reflection.Metadata;
 using System.Reflection.Metadata.Ecma335;
 using System.Reflection.PortableExecutable;
+using Microsoft.CodeAnalysis.CodeGen;
 using Microsoft.CodeAnalysis.CSharp.Symbols;
+using Microsoft.CodeAnalysis.CSharp.Test.Utilities;
 using Microsoft.CodeAnalysis.ExpressionEvaluator;
+using Microsoft.CodeAnalysis.Test.Utilities;
 using Microsoft.VisualStudio.Debugger.Evaluation.ClrCompilation;
 using Microsoft.DiaSymReader;
 using Roslyn.Test.PdbUtilities;
@@ -1051,6 +1054,67 @@ class B
                 includeSymbols: false);
             Assert.Null(error);
         }
+
+        [WorkItem(2441, "https://github.com/dotnet/roslyn/issues/2441")]
+        [Fact]
+        public void AssemblyQualifiedNameResolutionWithUnification()
+        {
+            var source1 = @"
+using SI = System.Int32;
+
+public class C1
+{
+    void M()
+    {
+    }
+}
+";
+
+            var source2 = @"
+public class C2 : C1
+{
+}
+";
+            ImmutableArray<MetadataReference> unused;
+
+            var comp1 = CreateCompilation(source1, new[] { MscorlibRef_v20}, TestOptions.DebugDll, assemblyName: "A");
+            byte[] dllBytes1;
+            byte[] pdbBytes1;
+            comp1.EmitAndGetReferences(out dllBytes1, out pdbBytes1, out unused);
+            var ref1 = AssemblyMetadata.CreateFromImage(dllBytes1).GetReference(display: "A");
+
+            var comp2 = CreateCompilation(source2, new[] { MscorlibRef_v4_0_30316_17626, ref1 }, TestOptions.DebugDll, assemblyName: "B");
+            byte[] dllBytes2;
+            byte[] pdbBytes2;
+            comp2.EmitAndGetReferences(out dllBytes2, out pdbBytes2, out unused);
+            var ref2 = AssemblyMetadata.CreateFromImage(dllBytes2).GetReference(display: "B");
+
+            var modulesBuilder = ArrayBuilder<ModuleInstance>.GetInstance();
+            modulesBuilder.Add(ref1.ToModuleInstance(dllBytes1, new SymReader(pdbBytes1, dllBytes1)));
+            modulesBuilder.Add(ref2.ToModuleInstance(dllBytes2, new SymReader(pdbBytes2, dllBytes2)));
+            modulesBuilder.Add(MscorlibRef_v4_0_30316_17626.ToModuleInstance(fullImage: null, symReader: null));
+            modulesBuilder.Add(ExpressionCompilerTestHelpers.IntrinsicAssemblyReference.ToModuleInstance(fullImage: null, symReader: null));
+
+            using (var runtime = new RuntimeInstance(modulesBuilder.ToImmutableAndFree()))
+            {
+                var context = CreateMethodContext(runtime, "C1.M");
+
+                string error;
+                var testData = new CompilationTestData();
+                context.CompileExpression("typeof(SI)", out error, testData);
+                Assert.Null(error);
+
+                testData.GetMethodData("<>x.<>m0").VerifyIL(@"
+{
+  // Code size       11 (0xb)
+  .maxstack  1
+  IL_0000:  ldtoken    ""int""
+  IL_0005:  call       ""System.Type System.Type.GetTypeFromHandle(System.RuntimeTypeHandle)""
+  IL_000a:  ret
+}
+");
+            }
+        }
     }
 
     internal static class ImportChainExtensions

src/ExpressionEvaluator/VisualBasic/Source/ExpressionCompiler/EETypeNameDecoder.vb

@@ -18,15 +18,16 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.ExpressionEvaluator
         End Sub
 
         Protected Overrides Function GetIndexOfReferencedAssembly(identity As AssemblyIdentity) As Integer
-            Dim assemblies = GetAssemblies()
+            Dim assemblyIdentities = Me.Module.GetReferencedAssemblies()
             ' Find assembly matching identity.
-            Dim index = assemblies.IndexOf(Function(assembly, id) id.Equals(assembly.Identity), identity)
+            Dim index = assemblyIdentities.IndexOf(identity)
             If index >= 0 Then
                 Return index
             End If
             If identity.IsWindowsComponent() Then
                 ' Find placeholder Windows.winmd assembly (created
                 ' in MetadataUtilities.MakeAssemblyReferences).
+                Dim assemblies = Me.Module.GetReferencedAssemblySymbols()
                 index = assemblies.IndexOf(Function(assembly, unused) assembly.Identity.IsWindowsRuntime(), DirectCast(Nothing, Object))
                 If index >= 0 Then
                     ' Find module in Windows.winmd matching identity.
@@ -49,7 +50,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.ExpressionEvaluator
         End Function
 
         Protected Overrides Function LookupTopLevelTypeDefSymbol(referencedAssemblyIndex As Integer, ByRef emittedName As MetadataTypeName) As TypeSymbol
-            Dim assembly = GetAssemblies()(referencedAssemblyIndex)
+            Dim assembly = Me.Module.GetReferencedAssemblySymbols()(referencedAssemblyIndex)
             Return assembly.LookupTopLevelMetadataType(emittedName, digThroughForwardedTypes:=True)
         End Function
 
@@ -57,14 +58,16 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.ExpressionEvaluator
             Return moduleSymbol.LookupTopLevelMetadataType(emittedName, isNoPiaLocalType)
         End Function
 
-        Private Function GetAssemblies() As ImmutableArray(Of AssemblySymbol)
-            Return _compilation.Assembly.Modules.Single().GetReferencedAssemblySymbols()
-        End Function
-
         Private Shared Function GetComponentAssemblyIdentity([module] As ModuleSymbol) As AssemblyIdentity
             Return DirectCast([module], PEModuleSymbol).Module.ReadAssemblyIdentityOrThrow()
         End Function
 
+        Private ReadOnly Property [Module] As ModuleSymbol
+            Get
+                Return _compilation.Assembly.Modules.Single()
+            End Get
+        End Property
+
     End Class
 
 End Namespace

src/ExpressionEvaluator/VisualBasic/Test/ExpressionCompiler/ImportDebugInfoTests.vb

@@ -7,7 +7,9 @@ Imports System.Reflection.Metadata
 Imports System.Reflection.Metadata.Ecma335
 Imports System.Reflection.PortableExecutable
 Imports System.Runtime.InteropServices
+Imports Microsoft.CodeAnalysis.CodeGen
 Imports Microsoft.CodeAnalysis.ExpressionEvaluator
+Imports Microsoft.CodeAnalysis.Test.Utilities
 Imports Microsoft.CodeAnalysis.VisualBasic.ExpressionEvaluator
 Imports Microsoft.CodeAnalysis.VisualBasic.Symbols
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
@@ -468,6 +470,61 @@ End Namespace
             Assert.Equal("http://xml1", xmlNamespaces("C").XmlNamespace)
         End Sub
 
+        <WorkItem(2441, "https://github.com/dotnet/roslyn/issues/2441")>
+        <Fact>
+        Public Sub AssemblyQualifiedNameResolutionWithUnification()
+            Const source1 = "
+Imports SI = System.Int32
+
+Public Class C1
+    Sub M()
+    End Sub
+End Class
+"
+
+            Const source2 = "
+Public Class C2 : Inherits C1
+End Class
+"
+
+            Dim comp1 = CreateCompilationWithReferences(VisualBasicSyntaxTree.ParseText(source1), {MscorlibRef_v20}, TestOptions.DebugDll, assemblyName:="A")
+            Dim dllBytes1 As Byte() = Nothing
+            Dim pdbBytes1 As Byte() = Nothing
+            comp1.EmitAndGetReferences(dllBytes1, pdbBytes1, Nothing)
+            Dim ref1 = AssemblyMetadata.CreateFromImage(dllBytes1).GetReference(display:="A")
+
+            Dim comp2 = CreateCompilationWithReferences(VisualBasicSyntaxTree.ParseText(source2), {MscorlibRef_v4_0_30316_17626, ref1}, TestOptions.DebugDll, assemblyName:="B")
+            Dim dllBytes2 As Byte() = Nothing
+            Dim pdbBytes2 As Byte() = Nothing
+            comp2.EmitAndGetReferences(dllBytes2, pdbBytes2, Nothing)
+            Dim ref2 = AssemblyMetadata.CreateFromImage(dllBytes2).GetReference(display:="B")
+
+            Dim modulesBuilder = ArrayBuilder(Of ModuleInstance).GetInstance()
+            modulesBuilder.Add(ref1.ToModuleInstance(dllBytes1, New SymReader(pdbBytes1, dllBytes1)))
+            modulesBuilder.Add(ref2.ToModuleInstance(dllBytes2, New SymReader(pdbBytes2, dllBytes2)))
+            modulesBuilder.Add(MscorlibRef_v4_0_30316_17626.ToModuleInstance(fullImage:=Nothing, symReader:=Nothing))
+            modulesBuilder.Add(ExpressionCompilerTestHelpers.IntrinsicAssemblyReference.ToModuleInstance(fullImage:=Nothing, symReader:=Nothing))
+
+            Using runtime As New RuntimeInstance(modulesBuilder.ToImmutableAndFree())
+                Dim context = CreateMethodContext(runtime, "C1.M")
+
+                Dim errorMessage As String = Nothing
+                Dim testData As New CompilationTestData()
+                context.CompileExpression("GetType(SI)", errorMessage, testData)
+                Assert.Null(errorMessage)
+
+                testData.GetMethodData("<>x.<>m0").VerifyIL("
+{
+  // Code size       11 (0xb)
+  .maxstack  1
+  IL_0000:  ldtoken    ""Integer""
+  IL_0005:  call       ""Function System.Type.GetTypeFromHandle(System.RuntimeTypeHandle) As System.Type""
+  IL_000a:  ret
+}
+")
+            End Using
+        End Sub
+
         Private Shared Function GetExpressionStatement(compilation As Compilation) As ExpressionStatementSyntax
             Return DirectCast(compilation.SyntaxTrees.Single().GetRoot().DescendantNodes().OfType(Of InvocationExpressionSyntax).Single().Parent, ExpressionStatementSyntax)
         End Function
@@ -511,7 +568,7 @@ End Namespace
             aliases = Nothing
             xmlNamespaces = Nothing
 
-            Const bindingFlags As BindingFlags = bindingFlags.NonPublic Or bindingFlags.Instance
+            Const bindingFlags As BindingFlags = BindingFlags.NonPublic Or BindingFlags.Instance
             Dim typesAndNamespacesField = GetType(ImportedTypesAndNamespacesMembersBinder).GetField("_importedSymbols", bindingFlags)
             Assert.NotNull(typesAndNamespacesField)
             Dim aliasesField = GetType(ImportAliasesBinder).GetField("_importedAliases", bindingFlags)