Support 'go to base' on a constructor symbol

src/EditorFeatures/CSharp/GoToBase/CSharpGoToBaseService.cs

@@ -4,9 +4,13 @@
 
 using System;
 using System.Composition;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.ExternalAccess.Pythia.Api;
 using Microsoft.CodeAnalysis.GoToBase;
 using Microsoft.CodeAnalysis.Host.Mef;
-using Microsoft.CodeAnalysis.Options;
 
 namespace Microsoft.CodeAnalysis.CSharp.GoToBase
 {
@@ -16,8 +20,25 @@ internal sealed class CSharpGoToBaseService : AbstractGoToBaseService
         [ImportingConstructor]
         [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
         public CSharpGoToBaseService()
-            : base()
         {
         }
+
+        protected override async Task<IMethodSymbol?> FindNextConstructorInChainAsync(
+            Solution solution, IMethodSymbol constructor, CancellationToken cancellationToken)
+        {
+            if (constructor.DeclaringSyntaxReferences.FirstOrDefault()?.GetSyntax(cancellationToken) is not ConstructorDeclarationSyntax constructorDeclaration)
+                return null;
+
+            var document = solution.GetDocument(constructorDeclaration.SyntaxTree);
+            if (document is null)
+                return null;
+
+            // this constructor must be calling an accessible no-arg constructor in the base type.
+            if (constructorDeclaration.Initializer is null)
+                return FindBaseNoArgConstructor(constructor);
+
+            var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
+            return semanticModel.GetSymbolInfo(constructorDeclaration.Initializer, cancellationToken).GetAnySymbol() as IMethodSymbol;
+        }
     }
 }

src/EditorFeatures/Test2/GoToBase/CSharpGoToBaseTests.vb

@@ -492,6 +492,118 @@ struct S : I { int I.$$P { get; set; } }
 interface I { int [|P|] { get; set; } }")
         End Function
 
+#End Region
+
+#Region "Constructors"
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain1() As Task
+            Await TestAsync("
+class C
+{
+    public $$C(int i) : this(i.ToString())
+    {
+    }
+
+    public [|C|](string s)
+    {
+    }
+}
+")
+        End Function
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain2() As Task
+            Await TestAsync("
+class Base
+{
+    public [|Base|](string s)
+    {
+    }
+}
+
+class C : Base
+{
+    public $$C(int i) : base(i.ToString())
+    {
+    }
+}
+")
+        End Function
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain3() As Task
+            Await TestAsync("
+class [|Base|]
+{
+}
+
+class C : Base
+{
+    public $$C(int i)
+    {
+    }
+}
+")
+        End Function
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain4() As Task
+            Await TestAsync("
+class Base
+{
+    public [|Base|](int i)
+    {
+    }
+}
+
+class C : Base
+{
+    public $$C(int i) : base(i)
+    {
+    }
+}
+")
+        End Function
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain5() As Task
+            Await TestAsync("
+class Base
+{
+    public [|Base|](int i = 0)
+    {
+    }
+}
+
+class C : Base
+{
+    public $$C(int i)
+    {
+    }
+}
+")
+        End Function
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain6() As Task
+            Await TestAsync("
+class Base
+{
+    public [|Base|](params int[] i)
+    {
+    }
+}
+
+class C : Base
+{
+    public $$C(int i)
+    {
+    }
+}
+")
+        End Function
+
 #End Region
 
     End Class

src/EditorFeatures/Test2/GoToBase/VisuaBasicGoToBaseTests.vb

@@ -667,5 +667,108 @@ End Interface")
         End Function
 #End Region
 
+#Region "Constructors"
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain1() As Task
+            Await TestAsync("
+class C
+    public sub $$new(i as integer)
+        me.new(i.ToString())
+    end sub
+
+    public sub [|new|](s as string)
+    end sub
+end class
+")
+        End Function
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain2() As Task
+            Await TestAsync("
+class Base
+    public sub [|new|](s as string)
+    end sub
+end class
+
+class C
+    inherits Base
+
+    public sub $$new(i as integer)
+        mybase.new(i.ToString())
+    end sub
+end sub
+")
+        End Function
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain3() As Task
+            Await TestAsync("
+class [|Base|]
+end class
+
+class C 
+    inherits Base
+
+    public sub $$new(i as integer)
+    end sub
+end class
+")
+        End Function
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain4() As Task
+            Await TestAsync("
+class Base
+    public sub [|new|](i as integer)
+    end sub
+end class
+
+class C 
+    inherits Base
+
+    public sub $$new(i as integer)
+        mybase.new(i)
+    end sub
+end class
+")
+        End Function
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain5() As Task
+            Await TestAsync("
+class Base
+    public sub [|new|](optional i as integer = 0)
+    end sub
+end class
+
+class C
+    inherits Base
+
+    public sub $$new(i as integer)
+    end sub
+end class
+")
+        End Function
+
+        <Fact, WorkItem(44944, "https://github.com/dotnet/roslyn/issues/44944")>
+        Public Async Function TestNextConstructorInChain6() As Task
+            Await TestAsync("
+class Base
+    public sub [|new|](paramarray i as integer())
+    end sub
+}
+
+class C
+    inherits Base
+
+    public sub $$new(i as integer)
+    end sub
+end class
+")
+        End Function
+
+#End Region
+
     End Class
 End Namespace

src/EditorFeatures/VisualBasic/GoToBase/VisualBasicGoToBaseService.vb

@@ -3,9 +3,10 @@
 ' See the LICENSE file in the project root for more information.
 
 Imports System.Composition
+Imports System.Threading
 Imports Microsoft.CodeAnalysis.GoToBase
 Imports Microsoft.CodeAnalysis.Host.Mef
-Imports Microsoft.CodeAnalysis.Options
+Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.VisualBasic.GoToBase
     <ExportLanguageService(GetType(IGoToBaseService), LanguageNames.VisualBasic), [Shared]>
@@ -15,7 +16,32 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.GoToBase
         <ImportingConstructor>
         <Obsolete(MefConstruction.ImportingConstructorMessage, True)>
         Public Sub New()
-            MyBase.New()
         End Sub
+
+        Protected Overrides Async Function FindNextConstructorInChainAsync(solution As Solution, constructor As IMethodSymbol, cancellationToken As CancellationToken) As Task(Of IMethodSymbol)
+            Dim subNew = TryCast(constructor.DeclaringSyntaxReferences.FirstOrDefault()?.GetSyntax(cancellationToken), SubNewStatementSyntax)
+            If subNew Is Nothing Then
+                Return Nothing
+            End If
+
+            Dim constructorBlock = TryCast(subNew.Parent, ConstructorBlockSyntax)
+            If constructorBlock Is Nothing Then
+                Return Nothing
+            End If
+
+            Dim initializer As MemberAccessExpressionSyntax = Nothing
+            If constructorBlock.Statements.Count = 0 OrElse
+               Not constructorBlock.Statements(0).IsConstructorInitializer(initializer) Then
+                Return FindBaseNoArgConstructor(constructor)
+            End If
+
+            Dim document = solution.GetDocument(constructorBlock.SyntaxTree)
+            If document Is Nothing Then
+                Return Nothing
+            End If
+
+            Dim semanticModel = Await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(False)
+            Return TryCast(semanticModel.GetSymbolInfo(initializer, cancellationToken).GetAnySymbol(), IMethodSymbol)
+        End Function
     End Class
 End Namespace

src/Features/Core/Portable/GoToBase/AbstractGoToBaseService.cs

@@ -2,19 +2,30 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Collections.Immutable;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.FindSymbols;
 using Microsoft.CodeAnalysis.FindUsages;
-using Microsoft.CodeAnalysis.Options;
+using Microsoft.CodeAnalysis.Shared.Extensions;
 
 namespace Microsoft.CodeAnalysis.GoToBase
 {
     internal abstract class AbstractGoToBaseService : IGoToBaseService
     {
-        protected AbstractGoToBaseService()
+        protected abstract Task<IMethodSymbol?> FindNextConstructorInChainAsync(
+            Solution solution, IMethodSymbol constructor, CancellationToken cancellationToken);
+
+        protected static IMethodSymbol? FindBaseNoArgConstructor(IMethodSymbol constructor)
         {
+            var baseType = constructor.ContainingType.BaseType;
+            if (baseType is null)
+                return null;
+
+            return baseType.InstanceConstructors.FirstOrDefault(
+                baseConstructor => baseConstructor.IsAccessibleWithin(constructor.ContainingType) &&
+                    baseConstructor.Parameters.All(p => p.IsOptional || p.IsParams));
         }
 
         public async Task FindBasesAsync(IFindUsagesContext context, Document document, int position, CancellationToken cancellationToken)
@@ -33,6 +44,12 @@ await context.ReportMessageAsync(
 
             var solution = project.Solution;
             var bases = await FindBaseHelpers.FindBasesAsync(symbol, solution, cancellationToken).ConfigureAwait(false);
+            if (bases.Length == 0 && symbol is IMethodSymbol { MethodKind: MethodKind.Constructor } constructor)
+            {
+                var nextConstructor = await FindNextConstructorInChainAsync(solution, constructor, cancellationToken).ConfigureAwait(false);
+                if (nextConstructor != null)
+                    bases = ImmutableArray.Create<ISymbol>(nextConstructor);
+            }
 
             await context.SetSearchTitleAsync(
                 string.Format(FeaturesResources._0_bases,