Custom Debug Info: VB Imports

Three more kinds:
1) # - don't produce it, but silently discard it as in dev12.
2) $ - don't produce it, but silently discard it as in dev12.
3) & - produce it for each linked assembly, but silently discard it (not needed in roslyn).

CR: ChuckS, AnGocke (changeset 1368608)

Src/Compilers/Core/Portable/PEWriter/NamespaceScope.cs

@@ -6,7 +6,7 @@
 namespace Microsoft.Cci
 {
     /// <summary>
-    /// This is a list of the using directives (including aliases) in a lexial scope.
+    /// This is a list of the using directives (including aliases) in a lexical scope.
     /// </summary>
     /// <remarks>
     /// This scope is tied to a particular method body, so that partial types can be accommodated.

Src/Compilers/Core/Portable/PEWriter/UsedNamespaceOrType.cs

@@ -94,6 +94,12 @@ internal static UsedNamespaceOrType CreateVisualBasicDefaultNamespace(string nam
             return new UsedNamespaceOrType(UsedNamespaceOrTypeKind.VBDefaultNamespace, name, null, externAlias: null, projectLevel: true);
         }
 
+        internal static UsedNamespaceOrType CreateVisualBasicEmbeddedPia(string name)
+        {
+            Debug.Assert(name != null);
+            return new UsedNamespaceOrType(UsedNamespaceOrTypeKind.VBEmbeddedPia, name, null, externAlias: null);
+        }
+
         private UsedNamespaceOrType(UsedNamespaceOrTypeKind kind, string name, string alias, string externAlias, bool projectLevel = false)
         {
             this.kind = kind;
@@ -171,9 +177,12 @@ public string Encode()
                     return this.name;
 
                 case UsedNamespaceOrTypeKind.VBDefaultNamespace:
-                    // VB marks the default/root namespace with an asteriks
+                    // VB marks the default/root namespace with an asterisk
                     return "*" + this.name;
 
+                case UsedNamespaceOrTypeKind.VBEmbeddedPia:
+                    return "&" + this.name;
+
                 default:
                     throw ExceptionUtilities.UnexpectedValue(this.kind);
             }

Src/Compilers/Core/Portable/PEWriter/UsedNamespaceOrTypeKind.cs

@@ -14,5 +14,6 @@ internal enum UsedNamespaceOrTypeKind
         VBXmlNamespace, // e.g. Imports <xmlns:ns="http://NewNamespace"> (VB only)
         VBCurrentNamespace, // the current namespace of the method's container
         VBDefaultNamespace, // the default namespace of the project
+        VBEmbeddedPia, // indicates that a type has been embedded from a given PIA
     }
 }

Src/Compilers/VisualBasic/Portable/Compilation/NamespaceScopeBuilder.vb

@@ -3,12 +3,7 @@
 Imports System.Collections.Concurrent
 Imports System.Collections.Immutable
 Imports System.Threading
-Imports Microsoft.CodeAnalysis
-Imports Microsoft.CodeAnalysis.CodeGen
-Imports Microsoft.CodeAnalysis.Text
-Imports Microsoft.CodeAnalysis.VisualBasic
 Imports Microsoft.CodeAnalysis.VisualBasic.Symbols
-Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.VisualBasic
 
@@ -19,6 +14,9 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
     ''' </summary>
     Friend Class NamespaceScopeBuilder
 
+        ' lazy embedded PIA imports
+        Private m_lazyEmbeddedPIAImports As Cci.NamespaceScope
+
         ' lazy project level imports
         Private m_lazyProjectLevelImports As Cci.NamespaceScope
 
@@ -52,6 +50,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
             Dim sourceModule = DirectCast(method.ContainingModule, SourceModuleSymbol)
 
+            If m_lazyEmbeddedPIAImports Is Nothing Then
+                Interlocked.CompareExchange(m_lazyEmbeddedPIAImports, BuildEmbeddedPiaImports(sourceModule), Nothing)
+            End If
+
             If m_lazyProjectLevelImports Is Nothing Then
                 Interlocked.CompareExchange(m_lazyProjectLevelImports, BuildProjectLevelImports(sourceModule), Nothing)
             End If
@@ -61,7 +63,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             End If
 
             ' Dev11 outputs them in LIFO order, which we can't do this exactly the same way because we store parts of the 
-            ' needed information in tree's.
+            ' needed information in trees.
             ' The order should be irrelevant because at the end it's a flat list, however we still output file level imports 
             ' before project level imports the same way as Dev11 did.
 
@@ -71,10 +73,33 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
             Return ImmutableArray.Create(sourceLevelImports,
                                          m_lazyDefaultNamespaceImport,
+                                         m_lazyEmbeddedPIAImports,
                                          m_lazyProjectLevelImports,
                                          BuildCurrentNamespace(method))
         End Function
 
+        ''' <remarks>
+        ''' Roslyn does not consume this information - it is only emitted for the benefit of legacy EEs.
+        ''' See Builder::WriteNoPiaPdbList.
+        ''' </remarks>
+        Private Function BuildEmbeddedPiaImports([module] As SourceModuleSymbol) As Cci.NamespaceScope
+            Dim embeddedPiasBuilder As ArrayBuilder(Of Cci.UsedNamespaceOrType) = Nothing
+
+            For Each referencedAssembly In [module].ReferencedAssemblySymbols
+                If referencedAssembly.IsLinked Then
+                    If embeddedPiasBuilder Is Nothing Then
+                        embeddedPiasBuilder = ArrayBuilder(Of Cci.UsedNamespaceOrType).GetInstance()
+                    End If
+
+                    ' NOTE: Dev12 does not seem to emit anything but the name (i.e. no version, token, etc).
+                    embeddedPiasBuilder.Add(Cci.UsedNamespaceOrType.CreateVisualBasicEmbeddedPia(referencedAssembly.Name))
+                End If
+            Next
+
+            Dim embeddedPias = If(embeddedPiasBuilder Is Nothing, ImmutableArray(Of Cci.UsedNamespaceOrType).Empty, embeddedPiasBuilder.ToImmutableAndFree())
+            Return New Cci.NamespaceScope(embeddedPias)
+        End Function
+
         Private Function BuildProjectLevelImports([module] As SourceModuleSymbol) As Cci.NamespaceScope
             Return BuildNamespaceScope([module].XmlNamespaces,
                                        [module].AliasImports,

Src/Compilers/VisualBasic/Test/Emit/PDB/PDBUsingTests.vb

 ' Copyright (c) Microsoft Open Technologies, Inc.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+Imports Microsoft.CodeAnalysis.Test.Utilities
+
 Namespace Microsoft.CodeAnalysis.VisualBasic.UnitTests.PDB
     Public Class PDBUsingTests
         Inherits BasicTestBase
@@ -288,5 +290,83 @@ End Class
 
             AssertXmlEqual(expected, GetSequencePoints(GetPdbXml(source, TestOptions.DebugDll, "C1.Main")))
         End Sub
+
+        <Fact>
+        Public Sub NoPia()
+            Dim piaSource = "
+Imports System.Runtime.InteropServices
+
+<assembly: PrimaryInteropAssembly(0, 0)>
+<assembly: Guid(""863D5BC0-46A1-49AC-97AA-A5F0D441A9DA"")>
+
+<ComImport>
+<Guid(""863D5BC0-46A1-49AD-97AA-A5F0D441A9D9"")>
+Public Interface I
+    Function F() As Object
+End Interface
+"
+            Dim piaComp = CreateCompilationWithMscorlib({piaSource}, compOptions:=TestOptions.DebugDll, assemblyName:="PIA")
+            AssertNoErrors(piaComp)
+            Dim piaRef = piaComp.EmitToImageReference(embedInteropTypes:=True)
+
+            Dim source = "
+Namespace N1
+    Class C
+        Shared Sub M()
+            Dim o As I = Nothing
+        End Sub
+    End Class
+End Namespace
+
+Namespace N2
+    Class D
+        Shared Sub M()
+        End Sub
+    End Class
+End Namespace
+"
+
+            Dim comp = CreateCompilationWithMscorlib({source}, {piaRef}, TestOptions.DebugDll)
+            AssertNoErrors(comp)
+
+            Dim expected =
+                <symbols>
+                    <methods>
+                        <method containingType="N1.C" name="M" parameterNames="">
+                            <customDebugInfo version="4" count="1">
+                                <encLocalSlotMap version="4" kind="EditAndContinueLocalSlotMap" size="12">
+                                    <slot kind="0" offset="4"/>
+                                </encLocalSlotMap>
+                            </customDebugInfo>
+                            <sequencepoints total="3">
+                                <entry il_offset="0x0" start_row="4" start_column="9" end_row="4" end_column="23" file_ref="0"/>
+                                <entry il_offset="0x1" start_row="5" start_column="17" end_row="5" end_column="33" file_ref="0"/>
+                                <entry il_offset="0x3" start_row="6" start_column="9" end_row="6" end_column="16" file_ref="0"/>
+                            </sequencepoints>
+                            <locals>
+                                <local name="o" il_index="0" il_start="0x0" il_end="0x4" attributes="0"/>
+                            </locals>
+                            <scope startOffset="0x0" endOffset="0x4">
+                                <defunct name="&amp;PIA"/>
+                                <currentnamespace name="N1"/>
+                                <local name="o" il_index="0" il_start="0x0" il_end="0x4" attributes="0"/>
+                            </scope>
+                        </method>
+                        <method containingType="N2.D" name="M" parameterNames="">
+                            <sequencepoints total="2">
+                                <entry il_offset="0x0" start_row="12" start_column="9" end_row="12" end_column="23" file_ref="0"/>
+                                <entry il_offset="0x1" start_row="13" start_column="9" end_row="13" end_column="16" file_ref="0"/>
+                            </sequencepoints>
+                            <locals/>
+                            <scope startOffset="0x0" endOffset="0x2">
+                                <defunct name="&amp;PIA"/>
+                                <currentnamespace name="N2"/>
+                            </scope>
+                        </method>
+                    </methods>
+                </symbols>
+            Dim actual = GetPdbXml(comp)
+            AssertXmlEqual(expected, actual)
+        End Sub
     End Class
 End Namespace

Src/Test/PdbUtilities/Pdb/PdbToXml.cs

@@ -775,6 +775,13 @@ private void WriteNamespace(ISymUnmanagedNamespace @namespace)
                         writer.WriteEndElement(); // </externinfo>
                     }
                     break;
+                case ImportTargetKind.Defunct:
+                    Debug.Assert(alias == null);
+                    Debug.Assert(scope == ImportScope.Unspecified);
+                    writer.WriteStartElement("defunct");
+                    writer.WriteAttributeString("name", rawName);
+                    writer.WriteEndElement(); // </defunct>
+                    break;
                 default:
                     Debug.Assert(false, "Unexpected import kind '" + kind + "'");
                     writer.WriteStartElement("unknown");

Src/Test/PdbUtilities/Shared/CustomDebugInfoReader.cs

@@ -519,7 +519,8 @@ private static void CheckVersion(byte globalVersion, int methodToken)
         /// </summary>
         /// <remarks>
         /// Doesn't consider forwarding.
-        /// TODO (acasey): VB doesn't just check the root scope - it digs around to find the best
+        /// 
+        /// CONSIDER: Dev12 doesn't just check the root scope - it digs around to find the best
         /// match based on the IL offset and then walks up to the root scope (see PdbUtil::GetScopeFromOffset).
         /// However, it's not clear that this matters, since imports can't be scoped in VB.  This is probably
         /// just based on the way they were extracting locals and constants based on a specific scope.
@@ -706,12 +707,20 @@ public static bool TryParseVisualBasicImportString(string import, out string ali
                 return true;
             }
 
-            // TODO (acasey): looks like we missed some cases (e.g. '$', '#', '&')
-            // See ProcedureContext::LoadImportsAndDefaultNamespaceNormal.
-
             int pos = 0;
             switch (import[pos])
             {
+                case '&':
+                    // Indicates the presence of embedded PIA types from a given assembly.  No longer required (as of Roslyn).
+                case '$':
+                case '#':
+                    // From ProcedureContext::LoadImportsAndDefaultNamespaceNormal:
+                    //   "Module Imports and extension types are no longer needed since we are not doing custom name lookup"
+                    alias = null;
+                    target = import;
+                    kind = ImportTargetKind.Defunct;
+                    scope = ImportScope.Unspecified;
+                    return true;
                 case '*': // VB default namespace
                     // see PEBuilder.cpp in vb\language\CodeGen
                     pos++;
@@ -890,6 +899,11 @@ internal enum ImportTargetKind
         /// VB root namespace (not an import).
         /// </summary>
         DefaultNamespace,
+
+        /// <summary>
+        /// A kind that is no longer used.
+        /// </summary>
+        Defunct,
     }
 
     internal enum ImportScope