Extensions: update xml docs to new metadata design

src/Compilers/CSharp/Portable/Binder/Semantics/Operators/UnaryOperatorOverloadResolution.cs

@@ -262,9 +262,9 @@ public bool Equals(MethodSymbol? x, MethodSymbol? y)
                 }
 
                 var xExtension = x.OriginalDefinition.ContainingType;
-                var xGroupingKey = ((SourceNamedTypeSymbol)xExtension).GetExtensionGroupingMetadataName();
+                var xGroupingKey = ((SourceNamedTypeSymbol)xExtension).ExtensionGroupingName;
                 var yExtension = y.OriginalDefinition.ContainingType;
-                var yGroupingKey = ((SourceNamedTypeSymbol)yExtension).GetExtensionGroupingMetadataName();
+                var yGroupingKey = ((SourceNamedTypeSymbol)yExtension).ExtensionGroupingName;
 
                 if (!xGroupingKey.Equals(yGroupingKey))
                 {
@@ -293,7 +293,7 @@ public int GetHashCode(MethodSymbol op)
                 int result = typeComparer.GetHashCode(op.OriginalDefinition.ContainingType.ContainingType);
 
                 var extension = op.OriginalDefinition.ContainingType;
-                var groupingKey = ((SourceNamedTypeSymbol)extension).GetExtensionGroupingMetadataName();
+                var groupingKey = ((SourceNamedTypeSymbol)extension).ExtensionGroupingName;
                 result = Hash.Combine(result, groupingKey.GetHashCode());
 
                 foreach (var parameter in op.OriginalDefinition.AsMember(Normalize(extension)).Parameters)

src/Compilers/CSharp/Portable/DocumentationComments/DocumentationCommentIDVisitor.PartVisitor.cs

@@ -175,15 +175,14 @@ public override object VisitTypeParameter(TypeParameterSymbol symbol, StringBuil
 
             public override object VisitNamedType(NamedTypeSymbol symbol, StringBuilder builder)
             {
-                if ((object)symbol.ContainingSymbol != null && symbol.ContainingSymbol.Name.Length != 0)
+                Symbol containingSymbol = symbol.ContainingSymbol;
+                if ((object)containingSymbol != null && (containingSymbol.Name.Length != 0 || containingSymbol is NamedTypeSymbol { IsExtension: true }))
                 {
-                    Visit(symbol.ContainingSymbol, builder);
+                    Visit(containingSymbol, builder);
                     builder.Append('.');
                 }
 
-                // PROTOTYPE: Finalize the doc ID story. When we refer to a member, we probably need to use grouping type name,
-                //            but when we refer to an extension block, we probably need to "dot" through both names. 
-                builder.Append(symbol.IsExtension ? symbol.ExtensionName : symbol.Name);
+                builder.Append(symbol.IsExtension ? symbol.ExtensionGroupingName : symbol.Name);
 
                 if (symbol.Arity != 0)
                 {

src/Compilers/CSharp/Portable/DocumentationComments/DocumentationCommentIDVisitor.cs

@@ -70,6 +70,11 @@ public override object VisitNamedType(NamedTypeSymbol symbol, StringBuilder buil
         {
             builder.Append("T:");
             PartVisitor.Instance.Visit(symbol, builder);
+            if (symbol.IsExtension)
+            {
+                builder.Append('.');
+                builder.Append(symbol.ExtensionMarkerName);
+            }
 
             return null;
         }

src/Compilers/CSharp/Portable/Emitter/Model/MethodSymbolAdapter.cs

@@ -310,7 +310,7 @@ Cci.ITypeDefinition Cci.ITypeDefinitionMember.ContainingTypeDefinition
                     return synthesizedGlobalMethod.ContainingPrivateImplementationDetailsType;
                 }
 
-                // PROTOTYPE: Share logic with Cci.ITypeMemberReference.GetContainingType implementation?
+                // Tracked by https://github.com/dotnet/roslyn/issues/78827 : code quality, share logic with Cci.ITypeMemberReference.GetContainingType implementation?
                 if (AdaptedMethodSymbol is SynthesizedExtensionMarker marker)
                 {
                     return ((SourceMemberContainerTypeSymbol)AdaptedMethodSymbol.ContainingType.ContainingType).GetExtensionGroupingInfo().GetCorrespondingMarkerType(marker);

src/Compilers/CSharp/Portable/Emitter/Model/PropertySymbolAdapter.cs

@@ -221,7 +221,7 @@ ITypeDefinition ITypeDefinitionMember.ContainingTypeDefinition
             {
                 CheckDefinitionInvariant();
 
-                // PROTOTYPE: Share logic with Cci.ITypeMemberReference.GetContainingType implementation?
+                // Tracked by https://github.com/dotnet/roslyn/issues/78827 : code quality, share logic with Cci.ITypeMemberReference.GetContainingType implementation?
                 if (AdaptedPropertySymbol.GetIsNewExtensionMember())
                 {
                     var containingType = AdaptedPropertySymbol.ContainingType;
@@ -249,7 +249,7 @@ ITypeReference ITypeMemberReference.GetContainingType(EmitContext context)
         {
             CheckDefinitionInvariant();
 
-            // PROTOTYPE: Share logic with Cci.ITypeMemberReference.GetContainingType implementation in MethodSymbolAdapter?
+            // Tracked by https://github.com/dotnet/roslyn/issues/78827 : code quality, share logic with Cci.ITypeMemberReference.GetContainingType implementation in MethodSymbolAdapter?
             if (AdaptedPropertySymbol.GetIsNewExtensionMember())
             {
                 var containingType = AdaptedPropertySymbol.ContainingType;

src/Compilers/CSharp/Portable/SymbolDisplay/SymbolDisplayVisitor.Types.cs

@@ -346,7 +346,7 @@ private void AddNameAndTypeArgumentsOrParameters(INamedTypeSymbol symbol)
                 if (Format.CompilerInternalOptions.HasFlag(SymbolDisplayCompilerInternalOptions.UseMetadataMemberNames))
                 {
                     // PROTOTYPE: What should we output as the name here
-                    var extensionIdentifier = underlyingTypeSymbol!.ExtensionName; // Tracked by https://github.com/dotnet/roslyn/issues/78957 : public API, use public API once it's available
+                    var extensionIdentifier = underlyingTypeSymbol!.ExtensionGroupingName; // Tracked by https://github.com/dotnet/roslyn/issues/78957 : public API, use public API once it's available
                     Builder.Add(CreatePart(SymbolDisplayPartKind.ClassName, symbol, extensionIdentifier));
                 }
                 else

src/Compilers/CSharp/Portable/Symbols/AnonymousTypes/PublicSymbols/AnonymousManager.TypeOrDelegatePublicSymbol.cs

@@ -82,7 +82,10 @@ internal sealed override bool MangleName
             internal sealed override bool IsFileLocal => false;
             internal sealed override FileIdentifier? AssociatedFileIdentifier => null;
 
-            internal override string ExtensionName
+            internal override string ExtensionGroupingName
+                => throw ExceptionUtilities.Unreachable();
+
+            internal override string ExtensionMarkerName
                 => throw ExceptionUtilities.Unreachable();
 
             public sealed override int Arity

src/Compilers/CSharp/Portable/Symbols/AnonymousTypes/SynthesizedSymbols/AnonymousType.TypeOrDelegateTemplateSymbol.cs

@@ -167,7 +167,10 @@ public sealed override bool IsRefLikeType
                 get { return false; }
             }
 
-            internal override string ExtensionName
+            internal override string ExtensionGroupingName
+                => throw ExceptionUtilities.Unreachable();
+
+            internal override string ExtensionMarkerName
                 => throw ExceptionUtilities.Unreachable();
 
             public sealed override bool IsReadOnly

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

@@ -116,7 +116,10 @@ public sealed override bool IsRefLikeType
             }
         }
 
-        internal override string ExtensionName
+        internal sealed override string ExtensionGroupingName
+            => throw ExceptionUtilities.Unreachable();
+
+        internal sealed override string ExtensionMarkerName
             => throw ExceptionUtilities.Unreachable();
 
         public sealed override bool IsReadOnly

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

@@ -2695,7 +2695,7 @@ public override bool IsRefLikeType
             }
         }
 
-        internal override string ExtensionName
+        internal override string ExtensionGroupingName
         {
             get
             {
@@ -2708,6 +2708,19 @@ internal override string ExtensionName
             }
         }
 
+        internal override string ExtensionMarkerName
+        {
+            get
+            {
+                if (!IsExtension)
+                {
+                    throw ExceptionUtilities.Unreachable();
+                }
+
+                return MetadataName;
+            }
+        }
+
         public override bool IsReadOnly
         {
             get

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

@@ -509,9 +509,15 @@ public override string MetadataName
         internal abstract FileIdentifier? AssociatedFileIdentifier { get; }
 
         /// <summary>
-        /// For extensions, returns the synthesized identifier for the type: "&lt;E>__N".
+        /// For extensions, returns the synthesized identifier for the grouping type.
         /// </summary>
-        internal abstract string ExtensionName { get; }
+        internal abstract string ExtensionGroupingName { get; }
+
+        /// <summary>
+        /// For extensions, returns the synthesized identifier for the marker type.
+        /// </summary>
+        internal abstract string ExtensionMarkerName { get; }
+
 #nullable disable
 
         /// <summary>

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

@@ -300,6 +300,12 @@ internal sealed override bool HasAsyncMethodBuilderAttribute(out TypeSymbol? bui
             return false;
         }
 
+        internal override string ExtensionGroupingName
+            => throw ExceptionUtilities.Unreachable();
+
+        internal override string ExtensionMarkerName
+            => throw ExceptionUtilities.Unreachable();
+
         private sealed class NativeIntegerTypeMap : AbstractTypeMap
         {
             private readonly NativeIntegerTypeSymbol _type;

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

@@ -471,5 +471,11 @@ internal sealed override bool HasAsyncMethodBuilderAttribute(out TypeSymbol? bui
         }
 
         internal override bool HasCompilerLoweringPreserveAttribute => _underlyingType.HasCompilerLoweringPreserveAttribute;
+
+        internal override string ExtensionGroupingName
+            => _underlyingType.ExtensionGroupingName;
+
+        internal override string ExtensionMarkerName
+            => _underlyingType.ExtensionMarkerName;
     }
 }

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

@@ -40,7 +40,7 @@ public ExtensionGroupingInfo(SourceMemberContainerTypeSymbol container)
                 }
 
                 var sourceNamedType = (SourceNamedTypeSymbol)type;
-                var groupingMetadataName = sourceNamedType.GetExtensionGroupingMetadataName();
+                var groupingMetadataName = sourceNamedType.ExtensionGroupingName;
 
                 MultiDictionary<string, SourceNamedTypeSymbol>? markerMap;
 
@@ -50,7 +50,7 @@ public ExtensionGroupingInfo(SourceMemberContainerTypeSymbol container)
                     groupingMap.Add(groupingMetadataName, markerMap);
                 }
 
-                markerMap.Add(sourceNamedType.GetExtensionMarkerMetadataName(), sourceNamedType);
+                markerMap.Add(sourceNamedType.ExtensionMarkerName, sourceNamedType);
             }
 
             _groupingMap = groupingMap;
@@ -80,13 +80,14 @@ public Cci.ITypeDefinition GetCorrespondingMarkerType(SynthesizedExtensionMarker
             return GetCorrespondingMarkerType((SourceNamedTypeSymbol)markerMethod.ContainingType);
         }
 
-        private ExtensionMarkerType GetCorrespondingMarkerType(SourceNamedTypeSymbol type)
+        private ExtensionMarkerType GetCorrespondingMarkerType(SourceNamedTypeSymbol extension)
         {
+            Debug.Assert(extension.IsExtension);
             GetGroupingTypes();
 
-            // PROTOTYPE: Optimize lookup with side dictionaries?
-            var groupingName = type.GetExtensionGroupingMetadataName();
-            var markerName = type.GetExtensionMarkerMetadataName();
+            // Tracked by https://github.com/dotnet/roslyn/issues/78827 : Optimize lookup with side dictionaries?
+            var groupingName = extension.ExtensionGroupingName;
+            var markerName = extension.ExtensionMarkerName;
 
             foreach (var groupingType in _lazyGroupingTypes)
             {
@@ -140,12 +141,13 @@ public Cci.TypeMemberVisibility GetCorrespondingMarkerMethodVisibility(Synthesiz
             return result;
         }
 
-        public Cci.ITypeDefinition GetCorrespondingGroupingType(SourceNamedTypeSymbol type)
+        public Cci.ITypeDefinition GetCorrespondingGroupingType(SourceNamedTypeSymbol extension)
         {
+            Debug.Assert(extension.IsExtension);
             GetGroupingTypes();
 
-            // PROTOTYPE: Optimize lookup with a side dictionary?
-            var groupingName = type.GetExtensionGroupingMetadataName();
+            // Tracked by https://github.com/dotnet/roslyn/issues/78827 : Optimize lookup with a side dictionary?
+            var groupingName = extension.ExtensionGroupingName;
 
             foreach (var groupingType in _lazyGroupingTypes)
             {
@@ -158,6 +160,30 @@ public Cci.ITypeDefinition GetCorrespondingGroupingType(SourceNamedTypeSymbol ty
             throw ExceptionUtilities.Unreachable();
         }
 
+        /// <summary>
+        /// Given an extension block, returns all the extensions that are grouped together with it
+        /// </summary>
+        internal ImmutableArray<SourceNamedTypeSymbol> GetMergedExtensions(SourceNamedTypeSymbol extension)
+        {
+            Debug.Assert(extension.IsExtension);
+            return GetCorrespondingMarkerType(extension).UnderlyingExtensions;
+        }
+
+        /// <summary>
+        /// Returns all the extension blocks but grouped/merged by equivalency (ie. same marker name)
+        /// </summary>
+        internal IEnumerable<ImmutableArray<SourceNamedTypeSymbol>> EnumerateMergedExtensionBlocks()
+        {
+            GetGroupingTypes();
+            foreach (var groupingType in _lazyGroupingTypes)
+            {
+                foreach (var markerType in groupingType.ExtensionMarkerTypes)
+                {
+                    yield return markerType.UnderlyingExtensions;
+                }
+            }
+        }
+
         private abstract class ExtensionGroupingOrMarkerType : Cci.INestedTypeDefinition
         {
             ushort ITypeDefinition.Alignment => 0;
@@ -368,7 +394,7 @@ public ExtensionGroupingType(string name, MultiDictionary<string, SourceNamedTyp
 
                 foreach (var pair in extensionMarkerTypes)
                 {
-                    builder.Add(new ExtensionMarkerType(this, pair.Key, pair.Value));
+                    builder.Add(new ExtensionMarkerType(this, name: pair.Key, extensions: pair.Value));
                 }
 
                 builder.Sort();
@@ -393,7 +419,15 @@ int IComparable<ExtensionGroupingType>.CompareTo(ExtensionGroupingType? other)
 
             protected override bool IsSealed => true;
 
-            protected override ITypeDefinition ContainingTypeDefinition => ExtensionMarkerTypes[0].UnderlyingExtensions[0].ContainingType!.GetCciAdapter();
+            protected override ITypeDefinition ContainingTypeDefinition
+            {
+                get
+                {
+                    NamedTypeSymbol? containingType = ExtensionMarkerTypes[0].UnderlyingExtensions[0].ContainingType;
+                    Debug.Assert(containingType is not null);
+                    return containingType.GetCciAdapter();
+                }
+            }
 
             public override string Name => _name;
 

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

@@ -195,7 +195,10 @@ internal sealed override bool HasCollectionBuilderAttribute(out TypeSymbol? buil
             return false;
         }
 
-        internal override string ExtensionName
+        internal override string ExtensionGroupingName
+            => throw ExceptionUtilities.Unreachable();
+
+        internal override string ExtensionMarkerName
             => throw ExceptionUtilities.Unreachable();
     }
 }

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

@@ -217,7 +217,7 @@ public bool SetHasDeclaredRequiredMembers(bool value)
         private ThreeState _lazyContainsExtensionMethods;
         private ThreeState _lazyAnyMemberHasAttributes;
 
-        // PROTOTYPE: Move some fields into "uncommon" class field?
+        // Tracked by https://github.com/dotnet/roslyn/issues/78827 : Optimize by moving some fields into "uncommon" class field?
         private ExtensionGroupingInfo? _lazyExtensionGroupingInfo;
 
         #region Construction
@@ -2190,7 +2190,7 @@ private static void ReportMethodSignatureCollision(SourceMemberContainerTypeSymb
                 method2 is SourceExtensionImplementationMethodSymbol { UnderlyingMethod: var underlying2 } &&
                 underlying1.IsStatic == underlying2.IsStatic &&
                 ((object)underlying1.ContainingType == underlying2.ContainingType ||
-                ((SourceNamedTypeSymbol)underlying1.ContainingType).GetExtensionGroupingMetadataName() == ((SourceNamedTypeSymbol)underlying2.ContainingType).GetExtensionGroupingMetadataName()) &&
+                ((SourceNamedTypeSymbol)underlying1.ContainingType).ExtensionGroupingName == ((SourceNamedTypeSymbol)underlying2.ContainingType).ExtensionGroupingName) &&
                 diagnostics.DiagnosticBag?.AsEnumerableWithoutResolution().Any(
                     static (d, arg) =>
                         (d.Code is (int)ErrorCode.ERR_OverloadRefKind or (int)ErrorCode.ERR_MemberAlreadyExists or
@@ -2387,7 +2387,7 @@ void checkMemberNameConflicts(
 
             void checkMemberNameConflictsInExtensions(BindingDiagnosticBag diagnostics)
             {
-                IEnumerable<IGrouping<string, NamedTypeSymbol>> extensionsByReceiverType = GetTypeMembers("").Where(static t => t.IsExtension).GroupBy(static t => ((SourceNamedTypeSymbol)t).GetExtensionGroupingMetadataName());
+                IEnumerable<IGrouping<string, NamedTypeSymbol>> extensionsByReceiverType = GetTypeMembers("").Where(static t => t.IsExtension).GroupBy(static t => ((SourceNamedTypeSymbol)t).ExtensionGroupingName);
 
                 foreach (var grouping in extensionsByReceiverType)
                 {

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

@@ -234,7 +234,7 @@ SynthesizedEventAccessorSymbol or
 
             if (target.GetIsNewExtensionMember())
             {
-                AddSynthesizedAttribute(ref attributes, moduleBuilder.SynthesizeExtensionMarkerNameAttribute(target, ((SourceNamedTypeSymbol)target.ContainingType).GetExtensionMarkerMetadataName()));
+                AddSynthesizedAttribute(ref attributes, moduleBuilder.SynthesizeExtensionMarkerNameAttribute(target, ((SourceNamedTypeSymbol)target.ContainingType).ExtensionMarkerName));
             }
         }
 

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

@@ -1826,7 +1826,7 @@ public override string MetadataName
             get
             {
                 return IsExtension
-                    ? GetExtensionMarkerMetadataName()
+                    ? ExtensionMarkerName
                     : base.MetadataName;
             }
         }