Expose ModuleMetadata off of IModuleSymbols.

src/Compilers/CSharp/Portable/Symbols/Metadata/PE/PEModuleSymbol.cs

@@ -682,5 +682,7 @@ internal IEnumerable<NamedTypeSymbol> GetForwardedTypes()
                 yield return assemblySymbol.LookupTopLevelMetadataType(ref name, digThroughForwardedTypes: true);
             }
         }
+
+        public override ModuleMetadata GetMetadata() => _module.GetMetadataCopy();
     }
 }

src/Compilers/CSharp/Portable/Symbols/MissingModuleSymbol.cs

@@ -183,6 +183,8 @@ internal override bool HasAssemblyRuntimeCompatibilityAttribute
         {
             get { return null; }
         }
+
+        public override ModuleMetadata GetMetadata() => null;
     }
 
     internal class MissingModuleSymbolWithName : MissingModuleSymbol

src/Compilers/CSharp/Portable/Symbols/ModuleSymbol.cs

@@ -377,6 +377,8 @@ public override TResult Accept<TResult>(SymbolVisitor<TResult> visitor)
             return visitor.VisitModule(this);
         }
 
+        public abstract ModuleMetadata GetMetadata();
+
         #endregion
     }
 }

src/Compilers/CSharp/Portable/Symbols/Retargeting/RetargetingModuleSymbol.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Collections.Immutable;
@@ -282,5 +283,7 @@ internal override bool HasAssemblyRuntimeCompatibilityAttribute
         {
             get { return null; }
         }
+
+        public override ModuleMetadata GetMetadata() => _underlyingModule.GetMetadata();
     }
-}
+}
\ No newline at end of file

src/Compilers/CSharp/Portable/Symbols/Source/SourceModuleSymbol.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
@@ -555,5 +556,7 @@ internal override bool HasAssemblyRuntimeCompatibilityAttribute
                 return data != null && data.HasDefaultCharSetAttribute ? data.DefaultCharacterSet : (CharSet?)null;
             }
         }
+
+        public override ModuleMetadata GetMetadata() => null;
     }
 }

src/Compilers/Core/Portable/MetadataReader/PEModule.cs

@@ -24,6 +24,9 @@ namespace Microsoft.CodeAnalysis
     /// </summary>
     internal sealed class PEModule : IDisposable
     {
+        // We need to store reference for to keep the metadata alive while symbols have reference to PEModule.
+        private readonly ModuleMetadata _owner;
+
         // Either we have PEReader or we have pointer and size of the metadata blob:
         private readonly PEReader _peReaderOpt;
         private readonly IntPtr _metadataPointerOpt;
@@ -76,13 +79,14 @@ internal sealed class PEModule : IDisposable
         private static readonly AttributeValueExtractor<ObsoleteAttributeData> s_attributeObsoleteDataExtractor = CrackObsoleteAttributeData;
         private static readonly AttributeValueExtractor<ObsoleteAttributeData> s_attributeDeprecatedDataExtractor = CrackDeprecatedAttributeData;
 
-        internal PEModule(PEReader peReader, IntPtr metadataOpt, int metadataSizeOpt, bool includeEmbeddedInteropTypes = false)
+        internal PEModule(ModuleMetadata owner, PEReader peReader, IntPtr metadataOpt, int metadataSizeOpt, bool includeEmbeddedInteropTypes = false)
         {
             // shall not throw
 
             Debug.Assert((peReader == null) ^ (metadataOpt == IntPtr.Zero && metadataSizeOpt == 0));
             Debug.Assert(metadataOpt == IntPtr.Zero || metadataSizeOpt > 0);
 
+            _owner = owner;
             _peReaderOpt = peReader;
             _metadataPointerOpt = metadataOpt;
             _metadataSizeOpt = metadataSizeOpt;
@@ -2966,5 +2970,7 @@ public unsafe override string GetString(byte* bytes, int byteCount)
                 return StringTable.AddSharedUTF8(bytes, byteCount);
             }
         }
+
+        public ModuleMetadata GetMetadataCopy() => _owner.Copy();
     }
 }

src/Compilers/Core/Portable/MetadataReference/ModuleMetadata.cs

@@ -24,13 +24,13 @@ public sealed partial class ModuleMetadata : Metadata
         private ModuleMetadata(PEReader peReader)
             : base(isImageOwner: true, id: new MetadataId())
         {
-            _module = new PEModule(peReader: peReader, metadataOpt: IntPtr.Zero, metadataSizeOpt: 0);
+            _module = new PEModule(this, peReader: peReader, metadataOpt: IntPtr.Zero, metadataSizeOpt: 0);
         }
 
         private ModuleMetadata(IntPtr metadata, int size, bool includeEmbeddedInteropTypes)
             : base(isImageOwner: true, id: new MetadataId())
         {
-            _module = new PEModule(peReader: null, metadataOpt: metadata, metadataSizeOpt: size, includeEmbeddedInteropTypes: includeEmbeddedInteropTypes);
+            _module = new PEModule(this, peReader: null, metadataOpt: metadata, metadataSizeOpt: size, includeEmbeddedInteropTypes: includeEmbeddedInteropTypes);
         }
 
         // creates a copy

src/Compilers/Core/Portable/PublicAPI.Unshipped.txt

@@ -87,6 +87,7 @@ Microsoft.CodeAnalysis.Emit.DebugInformationFormat.PortablePdb = 2 -> Microsoft.
 Microsoft.CodeAnalysis.IAssemblySymbol.GetMetadata() -> Microsoft.CodeAnalysis.AssemblyMetadata
 Microsoft.CodeAnalysis.ICompilationUnitSyntax
 Microsoft.CodeAnalysis.ICompilationUnitSyntax.EndOfFileToken.get -> Microsoft.CodeAnalysis.SyntaxToken
+Microsoft.CodeAnalysis.IModuleSymbol.GetMetadata() -> Microsoft.CodeAnalysis.ModuleMetadata
 Microsoft.CodeAnalysis.Metadata.Id.get -> Microsoft.CodeAnalysis.MetadataId
 Microsoft.CodeAnalysis.MetadataId
 Microsoft.CodeAnalysis.MetadataReference.MetadataReference(Microsoft.CodeAnalysis.MetadataReferenceProperties properties) -> void

src/Compilers/Core/Portable/Symbols/IModuleSymbol.cs

@@ -38,5 +38,13 @@ public interface IModuleSymbol : ISymbol
         /// from ReferencedAssemblySymbols correspond to each other.
         /// </summary>
         ImmutableArray<IAssemblySymbol> ReferencedAssemblySymbols { get; }
+
+        /// <summary>
+        /// If this is an <see cref="IModuleSymbol"/> for an <see cref="ModuleMetadata"/>,
+        /// this returns that <see cref="ModuleMetadata"/>.
+        /// 
+        /// Otherwise, this returns <code>null</code>.
+        /// </summary>
+        ModuleMetadata GetMetadata();
     }
 }

src/Compilers/Test/Utilities/VisualBasic/MockSymbols.vb

@@ -706,6 +706,10 @@ Friend Class MockModuleSymbol
             Return Nothing
         End Get
     End Property
+
+    Public Overrides Function GetMetadata() As ModuleMetadata
+        Return Nothing
+    End Function
 End Class
 
 Friend Class MockAssemblySymbol

src/Compilers/VisualBasic/Portable/Symbols/Metadata/PE/PEModuleSymbol.vb

@@ -457,5 +457,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols.Metadata.PE
             Next
         End Function
 
+        Public Overrides Function GetMetadata() As ModuleMetadata
+            Return _module.GetMetadataCopy()
+        End Function
     End Class
 End Namespace

src/Compilers/VisualBasic/Portable/Symbols/MissingModuleSymbol.vb

@@ -165,6 +165,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
                 Return Nothing
             End Get
         End Property
+
+        Public Overrides Function GetMetadata() As ModuleMetadata
+            Return Nothing
+        End Function
     End Class
 
     Friend Class MissingModuleSymbolWithName
@@ -200,5 +204,4 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
             Return other IsNot Nothing AndAlso m_Assembly.Equals(other.m_Assembly) AndAlso String.Equals(_name, other._name, StringComparison.OrdinalIgnoreCase)
         End Function
     End Class
-
-End Namespace
+End Namespace
\ No newline at end of file

src/Compilers/VisualBasic/Portable/Symbols/ModuleSymbol.vb

@@ -123,6 +123,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
             End Get
         End Property
 
+        Public MustOverride Function GetMetadata() As ModuleMetadata Implements IModuleSymbol.GetMetadata
+
         ''' <summary>
         ''' Returns an array of assembly identities for assemblies referenced by this module.
         ''' Items at the same position from GetReferencedAssemblies and from GetReferencedAssemblySymbols 

src/Compilers/VisualBasic/Portable/Symbols/Retargeting/RetargetingModuleSymbol.vb

@@ -273,5 +273,9 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols.Retargeting
         Public Overrides Function GetDocumentationCommentXml(Optional preferredCulture As CultureInfo = Nothing, Optional expandIncludes As Boolean = False, Optional cancellationToken As CancellationToken = Nothing) As String
             Return _underlyingModule.GetDocumentationCommentXml(preferredCulture, expandIncludes, cancellationToken)
         End Function
+
+        Public Overrides Function GetMetadata() As ModuleMetadata
+            Return _underlyingModule.GetMetadata()
+        End Function
     End Class
 End Namespace

src/Compilers/VisualBasic/Portable/Symbols/Source/SourceModuleSymbol.vb

@@ -1163,5 +1163,9 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
                 End Select
             Next
         End Sub
+
+        Public Overrides Function GetMetadata() As ModuleMetadata
+            Return Nothing
+        End Function
     End Class
 End Namespace

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

@@ -249,8 +249,9 @@ private static ImmutableArray<ImmutableArray<string>> GetGroupedImportStrings(Co
                     compilation.Emit(exebits, pdbbits);
 
                     exebits.Position = 0;
-                    using (var module = new PEModule(new PEReader(exebits, PEStreamOptions.LeaveOpen), metadataOpt: IntPtr.Zero, metadataSizeOpt: 0))
+                    using (var metadata = ModuleMetadata.CreateFromStream(exebits, leaveOpen: true))
                     {
+                        var module = metadata.Module;
                         var metadataReader = module.MetadataReader;
                         MethodDefinitionHandle methodHandle = metadataReader.MethodDefinitions.Single(mh => metadataReader.GetString(metadataReader.GetMethodDefinition(mh).Name) == methodName);
                         int methodToken = metadataReader.GetToken(methodHandle);

src/ExpressionEvaluator/Core/Test/ExpressionCompiler/ExpressionCompilerTestHelpers.cs

@@ -376,8 +376,9 @@ internal static ImmutableArray<string> GetLocalNames(this ISymUnmanagedReader sy
                 throw new NotImplementedException();
             }
 
-            using (var module = new PEModule(new PEReader(assembly), metadataOpt: IntPtr.Zero, metadataSizeOpt: 0))
+            using (var metadata = ModuleMetadata.CreateFromImage(assembly))
             {
+                var module = metadata.Module;
                 var reader = module.MetadataReader;
                 var typeDef = reader.GetTypeDef(parts[0]);
                 var methodName = parts[1];

src/ExpressionEvaluator/Core/Test/ExpressionCompiler/ModuleInstance.cs

@@ -97,10 +97,10 @@ internal int GetLocalSignatureToken(MethodDefinitionHandle methodHandle)
                 return 0;
             }
 
-            using (var module = new PEModule(new PEReader(ImmutableArray.CreateRange(this.FullImage)), metadataOpt: IntPtr.Zero, metadataSizeOpt: 0))
+            using (var metadata = ModuleMetadata.CreateFromImage(this.FullImage))
             {
-                var reader = module.MetadataReader;
-                var methodIL = module.GetMethodBodyOrThrow(methodHandle);
+                var reader = metadata.MetadataReader;
+                var methodIL = metadata.Module.GetMethodBodyOrThrow(methodHandle);
                 var localSignatureHandle = methodIL.LocalSignature;
                 return reader.GetToken(localSignatureHandle);
             }

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

@@ -124,7 +124,8 @@ End Namespace
                     compilation.Emit(exebits, pdbbits)
 
                     exebits.Position = 0
-                    Using [module] As New PEModule(New PEReader(exebits, PEStreamOptions.LeaveOpen), metadataOpt:=Nothing, metadataSizeOpt:=0)
+                    Using metadata = modulemetadata.CreateFromStream(exebits, leaveOpen:=True)
+                        Dim [module] = metadata.module
                         Dim metadataReader = [module].MetadataReader
                         Dim methodHandle = metadataReader.MethodDefinitions.Single(Function(mh) metadataReader.GetString(metadataReader.GetMethodDefinition(mh).Name) = methodName)
                         Dim methodToken = metadataReader.GetToken(methodHandle)