Directly expose AssemblyMetadata off of an IAssemblySymbol.

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

@@ -973,7 +973,7 @@ IEnumerable<IModuleSymbol> IAssemblySymbol.Modules
             }
         }
 
-        public abstract MetadataId MetadataId { get; }
+        public abstract AssemblyMetadata GetMetadata();
 
         INamedTypeSymbol IAssemblySymbol.ResolveForwardedType(string fullyQualifiedMetadataName)
         {

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

@@ -250,6 +250,6 @@ internal PEModuleSymbol PrimaryModule
             get { return null; }
         }
 
-        public override MetadataId MetadataId => _assembly.MetadataId;
+        public override AssemblyMetadata GetMetadata() => _assembly.GetMetadataCopy();
     }
 }

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

@@ -185,6 +185,6 @@ public override bool MightContainExtensionMethods
             }
         }
 
-        public override MetadataId MetadataId => null;
+        public override AssemblyMetadata GetMetadata() => null;
     }
 }

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

@@ -285,6 +285,6 @@ internal override NamedTypeSymbol TryLookupForwardedMetadataTypeWithCycleDetecti
             return this.RetargetingTranslator.Retarget(underlying, RetargetOptions.RetargetPrimitiveTypesByName);
         }
 
-        public override MetadataId MetadataId => _underlyingAssembly.MetadataId;
+        public override AssemblyMetadata GetMetadata() => _underlyingAssembly.GetMetadata();
     }
 }
\ No newline at end of file

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

@@ -2558,6 +2558,6 @@ internal override NamedTypeSymbol TryLookupForwardedMetadataTypeWithCycleDetecti
             return null;
         }
 
-        public override MetadataId MetadataId => null;
+        public override AssemblyMetadata GetMetadata() => null;
     }
-}
+}
\ No newline at end of file

src/Compilers/CSharp/Test/Symbol/Symbols/MockAssemblySymbol.cs

@@ -105,6 +105,6 @@ internal override NamedTypeSymbol TryLookupForwardedMetadataTypeWithCycleDetecti
             return null;
         }
 
-        public override MetadataId MetadataId => null;
+        public override AssemblyMetadata GetMetadata() => null;
     }
 }

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

@@ -175,6 +175,6 @@ internal bool DeclaresTheObjectClass
             }
         }
 
-        public MetadataId MetadataId => _owner.Id;
+        public AssemblyMetadata GetMetadataCopy() => _owner.Copy();
     }
 }

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

@@ -84,7 +84,7 @@ Microsoft.CodeAnalysis.Diagnostics.Telemetry.AnalyzerTelemetryInfo.SyntaxNodeAct
 Microsoft.CodeAnalysis.Diagnostics.Telemetry.AnalyzerTelemetryInfo.SyntaxTreeActionsCount.get -> int
 Microsoft.CodeAnalysis.Emit.DebugInformationFormat.Embedded = 3 -> Microsoft.CodeAnalysis.Emit.DebugInformationFormat
 Microsoft.CodeAnalysis.Emit.DebugInformationFormat.PortablePdb = 2 -> Microsoft.CodeAnalysis.Emit.DebugInformationFormat
-Microsoft.CodeAnalysis.IAssemblySymbol.MetadataId.get -> Microsoft.CodeAnalysis.MetadataId
+Microsoft.CodeAnalysis.IAssemblySymbol.GetMetadata() -> Microsoft.CodeAnalysis.AssemblyMetadata
 Microsoft.CodeAnalysis.ICompilationUnitSyntax
 Microsoft.CodeAnalysis.ICompilationUnitSyntax.EndOfFileToken.get -> Microsoft.CodeAnalysis.SyntaxToken
 Microsoft.CodeAnalysis.Metadata.Id.get -> Microsoft.CodeAnalysis.MetadataId

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

@@ -74,13 +74,10 @@ public interface IAssemblySymbol : ISymbol
 
         /// <summary>
         /// If this is an <see cref="IAssemblySymbol"/> for an <see cref="AssemblyMetadata"/>,
-        /// this returns the <see cref="Metadata.Id"/> for that <see cref="AssemblyMetadata"/>.
+        /// this returns that <see cref="AssemblyMetadata"/>.
         /// 
         /// Otherwise, this returns <code>null</code>.
-        /// 
-        /// If two assembly symbols are created from the same underlying <see cref="AssemblyMetadata"/>
-        /// object, then they will have the same Id.
         /// </summary>
-        MetadataId MetadataId { get; }
+        AssemblyMetadata GetMetadata();
     }
 }

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

@@ -803,9 +803,7 @@ Friend Class MockAssemblySymbol
         Return Nothing
     End Function
 
-    Public Overrides ReadOnly Property MetadataId As MetadataId
-        Get
-            Return Nothing
-        End Get
-    End Property
+    Public Overrides Function GetMetadata() As AssemblyMetadata
+        Return Nothing
+    End Function
 End Class

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

@@ -78,7 +78,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
             End Get
         End Property
 
-        Public MustOverride ReadOnly Property MetadataId As MetadataId Implements IAssemblySymbol.MetadataId
+        Public MustOverride Function GetMetadata() As AssemblyMetadata Implements IAssemblySymbol.GetMetadata
 
         ''' <summary>
         ''' Get the name of this assembly.

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

@@ -228,10 +228,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols.Metadata.PE
             End Get
         End Property
 
-        Public Overrides ReadOnly Property MetadataId As MetadataId
-            Get
-                Return _assembly.MetadataId
-            End Get
-        End Property
+        Public Overrides Function GetMetadata() As AssemblyMetadata
+            Return _assembly.GetMetadataCopy()
+        End Function
     End Class
 End Namespace
\ No newline at end of file

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

@@ -144,11 +144,9 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
             End Get
         End Property
 
-        Public Overrides ReadOnly Property MetadataId As MetadataId
-            Get
-                Return Nothing
-            End Get
-        End Property
+        Public Overrides Function GetMetadata() As AssemblyMetadata
+            Return Nothing
+        End Function
     End Class
 
     ''' <summary>

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

@@ -247,10 +247,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols.Retargeting
             Return Me.RetargetingTranslator.Retarget(underlying, RetargetOptions.RetargetPrimitiveTypesByName)
         End Function
 
-        Public Overrides ReadOnly Property MetadataId As MetadataId
-            Get
-                Return _underlyingAssembly.MetadataId
-            End Get
-        End Property
+        Public Overrides Function GetMetadata() As AssemblyMetadata
+            Return _underlyingAssembly.GetMetadata()
+        End Function
     End Class
 End Namespace

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

@@ -1683,10 +1683,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
             Return Nothing
         End Function
 
-        Public Overrides ReadOnly Property MetadataId As MetadataId
-            Get
-                Return Nothing
-            End Get
-        End Property
+        Public Overrides Function GetMetadata() As AssemblyMetadata
+            Return Nothing
+        End Function
     End Class
 End Namespace
\ No newline at end of file

src/Workspaces/Core/Portable/FindSymbols/SymbolTree/SymbolTreeInfo.cs

@@ -194,7 +194,7 @@ public static async Task<SymbolTreeInfo> TryGetInfoForAssemblyAsync(Solution sol
         {
             using (await s_assemblyInfosGate.DisposableWaitAsync(cancellationToken).ConfigureAwait(false))
             {
-                var metadataId = assembly.MetadataId;
+                var metadataId = assembly.GetMetadata()?.Id;
                 if (metadataId == null)
                 {
                     return null;