Add public API

src/Compilers/CSharp/Portable/Symbols/PublicModel/PropertySymbol.cs

@@ -109,6 +109,12 @@ ImmutableArray<CustomModifier> IPropertySymbol.RefCustomModifiers
 
         RefKind IPropertySymbol.RefKind => _underlying.RefKind;
 
+#nullable enable
+        IPropertySymbol? IPropertySymbol.PartialDefinitionPart => (_underlying as SourcePropertySymbol)?.PartialDefinitionPart.GetPublicSymbol();
+
+        IPropertySymbol? IPropertySymbol.PartialImplementationPart => (_underlying as SourcePropertySymbol)?.PartialImplementationPart.GetPublicSymbol();
+#nullable disable
+
         #region ISymbol Members
 
         protected override void Accept(SymbolVisitor visitor)

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

@@ -1,5 +1,7 @@
 Microsoft.CodeAnalysis.IParameterSymbol.IsParamsCollection.get -> bool
 Microsoft.CodeAnalysis.IParameterSymbol.IsParamsArray.get -> bool
+Microsoft.CodeAnalysis.IPropertySymbol.PartialDefinitionPart.get -> Microsoft.CodeAnalysis.IPropertySymbol?
+Microsoft.CodeAnalysis.IPropertySymbol.PartialImplementationPart.get -> Microsoft.CodeAnalysis.IMethodSymbol?
 Microsoft.CodeAnalysis.Operations.ArgumentKind.ParamCollection = 4 -> Microsoft.CodeAnalysis.Operations.ArgumentKind
 Microsoft.CodeAnalysis.Diagnostics.SuppressionInfo.ProgrammaticSuppressions.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.Diagnostics.Suppression>
 Microsoft.CodeAnalysis.Emit.InstrumentationKind.ModuleCancellation = 3 -> Microsoft.CodeAnalysis.Emit.InstrumentationKind

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

@@ -110,5 +110,17 @@ public interface IPropertySymbol : ISymbol
         /// The list of custom modifiers, if any, associated with the type of the property. 
         /// </summary>
         ImmutableArray<CustomModifier> TypeCustomModifiers { get; }
+
+        /// <summary>
+        /// If this is a partial property implementation part, returns the corresponding
+        /// definition part.  Otherwise null.
+        /// </summary>
+        IPropertySymbol? PartialDefinitionPart { get; }
+
+        /// <summary>
+        /// If this is a partial property definition part, returns the corresponding
+        /// implementation part.  Otherwise null.
+        /// </summary>
+        IPropertySymbol? PartialImplementationPart { get; }
     }
 }

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

@@ -621,6 +621,20 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
             End Get
         End Property
 
+        Private ReadOnly Property IPropertySymbol_PartialDefinitionPart As IPropertySymbol Implements IPropertySymbol.PartialDefinitionPart
+            Get
+                ' Feature not supported in VB
+                Return Nothing
+            End Get
+        End Property
+
+        Private ReadOnly Property IPropertySymbol_PartialImplementationPart As IPropertySymbol Implements IPropertySymbol.PartialImplementationPart
+            Get
+                ' Feature not supported in VB
+                Return Nothing
+            End Get
+        End Property
+
         Public Overrides Sub Accept(visitor As SymbolVisitor)
             visitor.VisitProperty(Me)
         End Sub

src/Features/Core/Portable/MetadataAsSource/AbstractMetadataAsSourceService.WrappedPropertySymbol.cs

@@ -66,5 +66,9 @@ public ImmutableArray<IPropertySymbol> ExplicitInterfaceImplementations
                 return this;
             }
         }
+
+        public IPropertySymbol PartialDefinitionPart => _symbol.PartialDefinitionPart;
+
+        public IPropertySymbol PartialImplementationPart => _symbol.PartialImplementationPart;
     }
 }

src/Workspaces/SharedUtilitiesAndExtensions/Workspace/Core/CodeGeneration/Symbols/CodeGenerationPropertySymbol.cs

@@ -85,4 +85,8 @@ public override TResult Accept<TArgument, TResult>(SymbolVisitor<TArgument, TRes
     public ImmutableArray<CustomModifier> RefCustomModifiers => [];
 
     public ImmutableArray<CustomModifier> TypeCustomModifiers => [];
+
+    public IPropertySymbol PartialImplementationPart => null;
+
+    public IPropertySymbol PartialDefinitionPart => null;
 }