Simple type/field binding works

src/Compilers/VisualBasic/Portable/Binding/Binder_Symbols.vb

@@ -4,6 +4,7 @@ Imports System.Collections.Generic
 Imports System.Collections.Immutable
 Imports System.Runtime.InteropServices
 Imports System.Threading
+Imports Microsoft.CodeAnalysis.Collections
 Imports Microsoft.CodeAnalysis.Text
 Imports Microsoft.CodeAnalysis.VisualBasic.Symbols
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
@@ -341,7 +342,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                         Dim diagName = GetBaseNamesForDiagnostic(typeSyntax)
                         diagInfo = NotFound(typeSyntax, diagName, binder, diagBag, reportedAnError)
 
-                        Return Binder.GetErrorSymbol(diagName, diagInfo)
+                        Return binder.GetErrorSymbol(diagName, diagInfo)
                     Else
                         If lookupResult.HasDiagnostic Then
                             Dim diagName = GetBaseNamesForDiagnostic(typeSyntax)
@@ -371,7 +372,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                 Binder.ReportDiagnostic(diagBag, typeSyntax, diagInfo)
                             End If
 
-                            Return Binder.GetErrorSymbol(GetBaseNamesForDiagnostic(typeSyntax), diagInfo, ImmutableArray.Create(Of Symbol)(sym), LookupResultKind.NotATypeOrNamespace)
+                            Return binder.GetErrorSymbol(GetBaseNamesForDiagnostic(typeSyntax), diagInfo, ImmutableArray.Create(Of Symbol)(sym), LookupResultKind.NotATypeOrNamespace)
                         Else
                             ' When we bind generic type reference, we pass through here with symbols for 
                             ' the generic type definition, each type argument and for the final constructed 
@@ -386,7 +387,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                 Emit.NoPia.EmbeddedTypesManager.IsValidEmbeddableType(DirectCast(typeSymbol, NamedTypeSymbol), typeSyntax, diagBag)
                             End If
 
-                            Binder.ReportDiagnosticsIfObsolete(diagBag, sym, typeSyntax)
+                            binder.ReportDiagnosticsIfObsolete(diagBag, sym, typeSyntax)
 
                             Return sym
                         End If
@@ -596,7 +597,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                             Binder.ReportDiagnostic(diagBag, typeSyntax, diagInfo)
                         End If
 
-                        Return Binder.GetErrorSymbol(diagName, diagInfo)
+                        Return binder.GetErrorSymbol(diagName, diagInfo)
                     Else
                         If lookupResult.HasDiagnostic Then
                             If Not reportedAnError Then
@@ -608,7 +609,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
                         ' LookupTypeOrNamespaceSyntax can't return more than one symbol.
                         Dim result = lookupResult.SingleSymbol
-                        Binder.ReportDiagnosticsIfObsolete(diagBag, result, typeSyntax)
+                        binder.ReportDiagnosticsIfObsolete(diagBag, result, typeSyntax)
                         Return result
                     End If
                 Finally
@@ -657,28 +658,16 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                         lookupResult.SetFrom(LookupGlobalName(DirectCast(typeSyntax, GlobalNameSyntax), binder))
 
                     Case SyntaxKind.PredefinedType
-                        LookupResult.SetFrom(LookupPredefinedTypeName(DirectCast(typeSyntax, PredefinedTypeSyntax), binder, diagBag, reportedAnError, suppressUseSiteError))
+                        lookupResult.SetFrom(LookupPredefinedTypeName(DirectCast(typeSyntax, PredefinedTypeSyntax), binder, diagBag, reportedAnError, suppressUseSiteError))
 
                     Case SyntaxKind.ArrayType
-                        LookupResult.SetFrom(LookupArrayType(DirectCast(typeSyntax, ArrayTypeSyntax), binder, diagBag, suppressUseSiteError, inGetTypeContext:=inGetTypeContext))
+                        lookupResult.SetFrom(LookupArrayType(DirectCast(typeSyntax, ArrayTypeSyntax), binder, diagBag, suppressUseSiteError, inGetTypeContext:=inGetTypeContext))
 
                     Case SyntaxKind.NullableType
-                        LookupResult.SetFrom(LookupNullableType(DirectCast(typeSyntax, NullableTypeSyntax), binder, diagBag, suppressUseSiteError))
+                        lookupResult.SetFrom(LookupNullableType(DirectCast(typeSyntax, NullableTypeSyntax), binder, diagBag, suppressUseSiteError))
 
                     Case SyntaxKind.TupleType
-                        'PROTOTYPE: tuple binding
-                        ' bind the first element for now to prevent crashing
-                        Dim tupleType = DirectCast(typeSyntax, TupleTypeSyntax)
-
-                        LookupTypeOrNamespaceSyntax(lookupResult,
-                                                           tupleType.TupleElements(0).Type,
-                                                           binder,
-                                                           diagBag,
-                                                           reportedAnError,
-                                                           unwrapAliases,
-                                                           suppressUseSiteError,
-                                                           inGetTypeContext,
-                                                           resolvingBaseType)
+                        lookupResult.SetFrom(LookupTupleType(DirectCast(typeSyntax, TupleTypeSyntax), binder, diagBag, suppressUseSiteError, inGetTypeContext, resolvingBaseType))
 
                     Case Else
                         Throw ExceptionUtilities.UnexpectedValue(typeSyntax.Kind)
@@ -690,6 +679,109 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 End If
             End Sub
 
+            Private Shared Function LookupTupleType(syntax As TupleTypeSyntax,
+                                                    binder As Binder,
+                                                    diagnostics As DiagnosticBag,
+                                                    suppressUseSiteError As Boolean,
+                                                    inGetTypeContext As Boolean,
+                                                    resolvingBaseType As Boolean) As TypeSymbol
+
+                Dim numElements As Integer = syntax.TupleElements.Count
+                Dim types = ArrayBuilder(Of TypeSymbol).GetInstance(numElements)
+                Dim locations = ArrayBuilder(Of Location).GetInstance(numElements)
+                Dim elementNames As ArrayBuilder(Of String) = Nothing
+
+                ' set of names already used
+                Dim uniqueFieldNames = PooledHashSet(Of String).GetInstance()
+                Dim countOfExplicitNames As Integer = 0
+
+                For i As Integer = 0 To numElements - 1
+                    Dim argumentSyntax = syntax.TupleElements(i)
+
+                    Dim argumentType As TypeSymbol = binder.BindTypeSyntax(argumentSyntax.Type, diagnostics, suppressUseSiteError, inGetTypeContext, resolvingBaseType)
+                    types.Add(argumentType)
+
+                    If argumentType.IsRestrictedType() Then
+                        Binder.ReportDiagnostic(diagnostics, argumentSyntax, ERRID.ERR_RestrictedType1, argumentType)
+                    End If
+
+                    Dim name As String = Nothing
+                    Dim nameSyntax As IdentifierNameSyntax = argumentSyntax.IdentifierName
+
+                    If nameSyntax IsNot Nothing Then
+                        name = nameSyntax.Identifier.ValueText
+
+                        ' validate name if we have one
+                        countOfExplicitNames += 1
+                        CheckTupleMemberName(binder, name, i, nameSyntax, diagnostics, uniqueFieldNames)
+                        locations.Add(nameSyntax.GetLocation)
+                    Else
+                        locations.Add(argumentSyntax.GetLocation)
+                    End If
+
+                    CollectTupleFieldMemberNames(name, i + 1, numElements, elementNames)
+                Next
+
+                uniqueFieldNames.Free()
+
+                If countOfExplicitNames <> 0 AndAlso countOfExplicitNames <> numElements Then
+                    Binder.ReportDiagnostic(diagnostics, syntax, ERRID.ERR_TupleExplicitNamesOnAllMembersOrNone)
+                End If
+
+                Dim typesArray As ImmutableArray(Of TypeSymbol) = types.ToImmutableAndFree()
+                Dim locationsArray As ImmutableArray(Of Location) = locations.ToImmutableAndFree()
+
+                If typesArray.Length < 2 Then
+                    'PROTOTYPE: tuples error ID
+                    Dim diaginfo = diagnostics.Add(ERRID.ERR_TupleTooFewElements, syntax.GetLocation)
+                    Return ErrorTypeSymbol.UnknownResultType
+                End If
+
+                Return TupleTypeSymbol.Create(syntax.GetLocation,
+                                            typesArray,
+                                            locationsArray,
+                                            If(elementNames Is Nothing, Nothing, elementNames.ToImmutableAndFree()),
+                                            binder.Compilation,
+                                            syntax,
+                                            diagnostics)
+            End Function
+
+            Private Shared Sub CollectTupleFieldMemberNames(name As String, position As Integer, tupleSize As Integer, ByRef elementNames As ArrayBuilder(Of String))
+                ' add the name to the list
+                ' names would typically all be there Or none at all
+                ' but in case we need to handle this in error cases
+                If elementNames IsNot Nothing Then
+                    elementNames.Add(If(name, TupleTypeSymbol.TupleMemberName(position)))
+                Else
+                    If name IsNot Nothing Then
+                        elementNames = ArrayBuilder(Of String).GetInstance(tupleSize)
+                        For j As Integer = 1 To position - 1
+                            elementNames.Add(TupleTypeSymbol.TupleMemberName(j))
+                        Next
+                        elementNames.Add(name)
+                    End If
+                End If
+            End Sub
+
+            Private Shared Function CheckTupleMemberName(binder As Binder, name As String, position As Integer, syntax As VisualBasicSyntaxNode, diagnostics As DiagnosticBag, uniqueFieldNames As PooledHashSet(Of String)) As Boolean
+                Dim reserved As Integer = TupleTypeSymbol.IsElementNameReserved(name)
+                If reserved = 0 Then
+                    Binder.ReportDiagnostic(diagnostics, syntax, ERRID.ERR_TupleReservedMemberNameAnyPosition, name)
+                    Return False
+
+                ElseIf reserved > 0 AndAlso reserved <> position + 1 Then
+                    Binder.ReportDiagnostic(diagnostics, syntax, ERRID.ERR_TupleReservedMemberName, name, reserved)
+                    Return False
+
+                ElseIf (Not uniqueFieldNames.Add(name)) Then
+                    Binder.ReportDiagnostic(diagnostics, syntax, ERRID.ERR_TupleDuplicateMemberName)
+                    Return False
+
+                End If
+
+                Return True
+            End Function
+
             Private Shared Sub AnalyzeLookupResultForIllegalBaseTypeReferences(lookupResult As LookupResult,
                                                                                typeSyntax As TypeSyntax,
                                                                                binder As Binder,
@@ -748,9 +840,9 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             Private Shared Function ErrorTypeFromLookupResult(name As String, result As LookupResult, binder As Binder) As ErrorTypeSymbol
                 If result.Kind = LookupResultKind.Ambiguous AndAlso result.HasSingleSymbol AndAlso TypeOf result.Diagnostic Is AmbiguousSymbolDiagnostic Then
                     ' Special case: set of ambiguous symbols is stored in the diagnostics.
-                    Return Binder.GetErrorSymbol(name, result.Diagnostic, DirectCast(result.Diagnostic, AmbiguousSymbolDiagnostic).AmbiguousSymbols, result.Kind)
+                    Return binder.GetErrorSymbol(name, result.Diagnostic, DirectCast(result.Diagnostic, AmbiguousSymbolDiagnostic).AmbiguousSymbols, result.Kind)
                 End If
-                Return Binder.GetErrorSymbol(name, result.Diagnostic, result.Symbols.ToImmutable(), result.Kind)
+                Return binder.GetErrorSymbol(name, result.Diagnostic, result.Symbols.ToImmutable(), result.Kind)
             End Function
 
             ''' <summary>
@@ -764,7 +856,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 If sym.IsNamespace Then
                     Dim diagInfo = New BadSymbolDiagnostic(sym, ERRID.ERR_UnrecognizedType)
                     Binder.ReportDiagnostic(diagBag, syntax, diagInfo)
-                    Return Binder.GetErrorSymbol(sym.Name, diagInfo, ImmutableArray.Create(Of Symbol)(sym), LookupResultKind.NotATypeOrNamespace)
+                    Return binder.GetErrorSymbol(sym.Name, diagInfo, ImmutableArray.Create(Of Symbol)(sym), LookupResultKind.NotATypeOrNamespace)
                 Else
                     Return DirectCast(sym, TypeSymbol)
                 End If
@@ -825,7 +917,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                         Throw ExceptionUtilities.UnexpectedValue(predefinedType)
                 End Select
 
-                Dim sym = Binder.GetSpecialType(type, node, diagBag, reportedAnError, suppressUseSiteError)
+                Dim sym = binder.GetSpecialType(type, node, diagBag, reportedAnError, suppressUseSiteError)
                 Return SingleLookupResult.Good(sym)
             End Function
 
@@ -837,7 +929,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                                     diagBag As DiagnosticBag,
                                                     suppressUseSiteError As Boolean,
                                                     inGetTypeContext As Boolean) As SingleLookupResult
-                Dim elementType As TypeSymbol = Binder.BindTypeSyntax(arrayTypeSyntax.ElementType,
+                Dim elementType As TypeSymbol = binder.BindTypeSyntax(arrayTypeSyntax.ElementType,
                                                                       diagBag,
                                                                       suppressUseSiteError:=suppressUseSiteError,
                                                                       inGetTypeContext:=inGetTypeContext)
@@ -851,8 +943,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                                        binder As Binder,
                                                        diagBag As DiagnosticBag,
                                                        suppressUseSiteError As Boolean) As SingleLookupResult
-                Dim elementType As TypeSymbol = Binder.BindTypeSyntax(nullableTypeSyntax.ElementType, diagBag, suppressUseSiteError)
-                Return SingleLookupResult.Good(Binder.CreateNullableOf(elementType, nullableTypeSyntax, nullableTypeSyntax.ElementType, diagBag))
+                Dim elementType As TypeSymbol = binder.BindTypeSyntax(nullableTypeSyntax.ElementType, diagBag, suppressUseSiteError)
+                Return SingleLookupResult.Good(binder.CreateNullableOf(elementType, nullableTypeSyntax, nullableTypeSyntax.ElementType, diagBag))
             End Function
 
             ''' <summary>
@@ -928,7 +1020,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                         ' TODO: Dev10 squiggles type arguments for this error, but Roslyn will squiggle the whole type name.
                         '       If we want to preserve Dev10 behavior, it should be possible to provide optional location/syntax node 
                         '       for the diagnostic attached to LookupResult.
-                        LookupResult.SetFrom(SingleLookupResult.WrongArity(lookupResult.SingleSymbol,
+                        lookupResult.SetFrom(SingleLookupResult.WrongArity(lookupResult.SingleSymbol,
                                 New BadSymbolDiagnostic(lookupResult.SingleSymbol, ERRID.ERR_TypeOrMemberNotGeneric1, lookupResult.SingleSymbol)))
                     End If
                 Else
@@ -939,11 +1031,11 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                     End If
 
                     ' Construct the type and validate constraints.
-                    Dim constructedType = Binder.ConstructAndValidateConstraints(
+                    Dim constructedType = binder.ConstructAndValidateConstraints(
                         genericType, typeArguments, genericNameSyntax, typeArgumentsSyntax.Arguments, diagBag)
 
                     ' Put the constructed type in. Note that this preserves any error associated with the lookupResult.
-                    LookupResult.ReplaceSymbol(constructedType)
+                    lookupResult.ReplaceSymbol(constructedType)
                 End If
             End Sub
 
@@ -985,7 +1077,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
                 Dim leftSymbol As NamespaceOrTypeSymbol = DirectCast(lookupResult.SingleSymbol, NamespaceOrTypeSymbol)
 
-                Binder.ReportDiagnosticsIfObsolete(diagBag, leftSymbol, leftNameSyntax)
+                binder.ReportDiagnosticsIfObsolete(diagBag, leftSymbol, leftNameSyntax)
 
                 lookupResult.Clear()
                 Dim useSiteDiagnostics As HashSet(Of DiagnosticInfo) = Nothing
@@ -1060,7 +1152,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
                 Dim leftSymbol As NamespaceOrTypeSymbol = DirectCast(lookupResult.SingleSymbol, NamespaceOrTypeSymbol)
 
-                Binder.ReportDiagnosticsIfObsolete(diagBag, leftSymbol, leftNameSyntax)
+                binder.ReportDiagnosticsIfObsolete(diagBag, leftSymbol, leftNameSyntax)
 
                 ' Lookup the generic type.
                 lookupResult.Clear()
@@ -1087,11 +1179,11 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                     Return
                 Else
                     ' Construct the type and validate constraints.
-                    Dim constructedType = Binder.ConstructAndValidateConstraints(
+                    Dim constructedType = binder.ConstructAndValidateConstraints(
                         genericType, typeArguments, genDottedNameSyntax, typeArgumentsSyntax.Arguments, diagBag)
 
                     ' Note: this preserves any error associated with the generic type, which is what we want.
-                    LookupResult.ReplaceSymbol(constructedType)
+                    lookupResult.ReplaceSymbol(constructedType)
                 End If
             End Sub
 
@@ -1114,7 +1206,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 Dim types As TypeSymbol() = New TypeSymbol(0 To arity - 1) {}
 
                 For i As Integer = 0 To arity - 1
-                    types(i) = Binder.BindTypeSyntax(typeArgumentsSyntax.Arguments(i), diagBag, suppressUseSiteError)
+                    types(i) = binder.BindTypeSyntax(typeArgumentsSyntax.Arguments(i), diagBag, suppressUseSiteError)
                 Next
 
                 Return types.AsImmutableOrNull()

src/Compilers/VisualBasic/Portable/Emit/SymbolTranslator.vb

@@ -120,6 +120,9 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Emit
             ' Anonymous type being translated
             If namedTypeSymbol.IsAnonymousType Then
                 namedTypeSymbol = AnonymousTypeManager.TranslateAnonymousTypeSymbol(namedTypeSymbol)
+            ElseIf (namedTypeSymbol.IsTupleType) Then
+                Debug.Assert(Not needDeclaration)
+                namedTypeSymbol = namedTypeSymbol.TupleUnderlyingType
             End If
 
             ' Substitute error types with a special singleton object.
@@ -234,6 +237,9 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Emit
         ) As Microsoft.Cci.IFieldReference
             Debug.Assert(fieldSymbol Is fieldSymbol.OriginalDefinition OrElse
                                             Not fieldSymbol.Equals(fieldSymbol.OriginalDefinition))
+            If fieldSymbol.IsTupleField Then
+                fieldSymbol = fieldSymbol.TupleUnderlyingField
+            End If
 
             Me.ProcessReferencedSymbol(fieldSymbol)
 
@@ -473,6 +479,5 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Emit
         Friend Overloads Function Translate(symbol As ArrayTypeSymbol) As Microsoft.Cci.IArrayTypeReference
             Return symbol
         End Function
-
     End Class
 End Namespace

src/Compilers/VisualBasic/Portable/Errors/Errors.vb

@@ -1687,6 +1687,12 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
         ERR_OptionMustBeAbsolutePath = 37257
 
+        ERR_TupleExplicitNamesOnAllMembersOrNone = 37258
+        ERR_TupleTooFewElements = 37259
+        ERR_TupleReservedMemberNameAnyPosition = 37260
+        ERR_TupleReservedMemberName = 37261
+        ERR_TupleDuplicateMemberName = 37262
+
         ERR_LastPlusOne
 
 

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

@@ -1237,5 +1237,66 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
 
 #End Region
 
+        ''' <summary>
+        ''' Verify if the given type can be used to back a tuple type 
+        ''' and return cardinality of that tuple type in <paramref name="tupleCardinality"/>. 
+        ''' </summary>
+        ''' <param name="tupleCardinality">If method returns true, contains cardinality of the compatible tuple type.</param>
+        ''' <returns></returns>
+        Public Overrides Function IsTupleCompatible(<Out> ByRef tupleCardinality As Integer) As Boolean
+            If IsTupleType Then
+                tupleCardinality = 0
+                Return False
+            End If
+
+            ' Should this be optimized for perf (caching for VT<0> to VT<7>, etc.)?
+            If (Not IsUnboundGenericType AndAlso
+                ContainingSymbol?.Kind = SymbolKind.Namespace AndAlso
+                ContainingNamespace.ContainingNamespace?.IsGlobalNamespace = True AndAlso
+                Name = TupleTypeSymbol.TupleTypeName AndAlso
+                ContainingNamespace.Name = MetadataHelpers.SystemString) Then
+
+                Dim arity = Me.Arity
+
+                If arity > 0 AndAlso arity < TupleTypeSymbol.RestPosition Then
+                    tupleCardinality = arity
+                    Return True
+                ElseIf arity = TupleTypeSymbol.RestPosition AndAlso Not IsDefinition Then
+                    ' Skip through "Rest" extensions
+                    Dim typeToCheck As TypeSymbol = Me
+                    Dim levelsOfNesting As Integer = 0
+
+                    Do
+                        levelsOfNesting += 1
+                        typeToCheck = DirectCast(typeToCheck, NamedTypeSymbol).TypeArgumentsNoUseSiteDiagnostics(TupleTypeSymbol.RestPosition - 1)
+                    Loop While typeToCheck.OriginalDefinition = Me.OriginalDefinition AndAlso Not typeToCheck.IsDefinition
+
+                    If typeToCheck.IsTupleType Then
+                        Dim underlying = typeToCheck.TupleUnderlyingType
+                        If underlying.Arity = TupleTypeSymbol.RestPosition AndAlso underlying.OriginalDefinition <> Me.OriginalDefinition Then
+                            tupleCardinality = 0
+                            Return False
+                        End If
+
+                        tupleCardinality = (TupleTypeSymbol.RestPosition - 1) * levelsOfNesting + typeToCheck.TupleElementTypes.Length
+                        Return True
+                    End If
+
+                    arity = If(TryCast(typeToCheck, NamedTypeSymbol)?.Arity, 0)
+
+                    If arity > 0 AndAlso
+                        arity < TupleTypeSymbol.RestPosition AndAlso
+                        typeToCheck.IsTupleCompatible(tupleCardinality) Then
+                        Debug.Assert(tupleCardinality < TupleTypeSymbol.RestPosition)
+                        tupleCardinality += (TupleTypeSymbol.RestPosition - 1) * levelsOfNesting
+                        Return True
+                    End If
+                End If
+            End If
+
+            tupleCardinality = 0
+            Return False
+        End Function
+
     End Class
 End Namespace

src/Compilers/VisualBasic/Portable/Symbols/Tuples/TupleTypeSymbol.vb

@@ -478,8 +478,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
         End Function
 
         Private Shared Function NumberOfValueTuples(numElements As Integer, <Out()> ByRef remainder As Integer) As Integer
-            remainder = (numElements - 1) Mod TupleTypeSymbol.RestPosition - 1 + 1
-            Return (numElements - 1) \ TupleTypeSymbol.RestPosition - 1 + 1
+            remainder = (numElements - 1) Mod (RestPosition - 1) + 1
+            Return (numElements - 1) \ (RestPosition - 1) + 1
         End Function
 
         Private Shared Function GetTupleUnderlyingType(elementTypes As ImmutableArray(Of TypeSymbol), syntax As VisualBasicSyntaxNode, compilation As VisualBasicCompilation, diagnostics As DiagnosticBag) As NamedTypeSymbol
@@ -493,7 +493,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
                 Binder.ReportUseSiteError(diagnostics, syntax, wellKnownType)
             End If
 
-            Dim namedTypeSymbol As NamedTypeSymbol = wellKnownType.Construct(ImmutableArray.Create(Of TypeSymbol)(elementTypes, (chainLength - 1) * TupleTypeSymbol.RestPosition - 1, remainder))
+            Dim namedTypeSymbol As NamedTypeSymbol = wellKnownType.Construct(ImmutableArray.Create(Of TypeSymbol)(elementTypes, (chainLength - 1) * (TupleTypeSymbol.RestPosition - 1), remainder))
             Dim [loop] As Integer = chainLength - 1
             If [loop] > 0 Then
                 Dim wellKnownType2 As NamedTypeSymbol = compilation.GetWellKnownType(TupleTypeSymbol.GetTupleType(TupleTypeSymbol.RestPosition))
@@ -502,7 +502,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
                     Binder.ReportUseSiteError(diagnostics, syntax, wellKnownType2)
                 End If
                 Do
-                    Dim typeArguments As ImmutableArray(Of TypeSymbol) = ImmutableArray.Create(Of TypeSymbol)(elementTypes, ([loop] - 1) * TupleTypeSymbol.RestPosition - 1, TupleTypeSymbol.RestPosition - 1).Add(namedTypeSymbol)
+                    Dim typeArguments As ImmutableArray(Of TypeSymbol) = ImmutableArray.Create(Of TypeSymbol)(elementTypes, ([loop] - 1) * (TupleTypeSymbol.RestPosition - 1), TupleTypeSymbol.RestPosition - 1).Add(namedTypeSymbol)
                     namedTypeSymbol = wellKnownType2.Construct(typeArguments)
                     [loop] -= 1
                 Loop While [loop] > 0
@@ -661,7 +661,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
                             Dim field = DirectCast(member, FieldSymbol)
 
                             Dim tupleFieldIndex = currentFieldsForElements.IndexOf(field, ReferenceEqualityComparer.Instance)
-                            If tupleFieldIndex = 0 Then
+                            If tupleFieldIndex >= 0 Then
                                 ' This Is a tuple backing field
                                 Dim FieldSymbol = field.AsMember(currentUnderlying)
 

src/Compilers/VisualBasic/Portable/VBResources.Designer.vb

@@ -10325,6 +10325,51 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             End Get
         End Property
         
+        '''<summary>
+        '''  Looks up a localized string similar to Tuple member names must be unique..
+        '''</summary>
+        Friend ReadOnly Property ERR_TupleDuplicateMemberName() As String
+            Get
+                Return ResourceManager.GetString("ERR_TupleDuplicateMemberName", resourceCulture)
+            End Get
+        End Property
+        
+        '''<summary>
+        '''  Looks up a localized string similar to Tuple member names must all be provided, if any one is provided..
+        '''</summary>
+        Friend ReadOnly Property ERR_TupleExplicitNamesOnAllMembersOrNone() As String
+            Get
+                Return ResourceManager.GetString("ERR_TupleExplicitNamesOnAllMembersOrNone", resourceCulture)
+            End Get
+        End Property
+        
+        '''<summary>
+        '''  Looks up a localized string similar to Tuple member name &apos;{0}&apos; is only allowed at position {1}..
+        '''</summary>
+        Friend ReadOnly Property ERR_TupleReservedMemberName() As String
+            Get
+                Return ResourceManager.GetString("ERR_TupleReservedMemberName", resourceCulture)
+            End Get
+        End Property
+        
+        '''<summary>
+        '''  Looks up a localized string similar to Tuple membername &apos;{0}&apos; is disallowed at any position..
+        '''</summary>
+        Friend ReadOnly Property ERR_TupleReservedMemberNameAnyPosition() As String
+            Get
+                Return ResourceManager.GetString("ERR_TupleReservedMemberNameAnyPosition", resourceCulture)
+            End Get
+        End Property
+        
+        '''<summary>
+        '''  Looks up a localized string similar to Tuple must contain at least two elements..
+        '''</summary>
+        Friend ReadOnly Property ERR_TupleTooFewElements() As String
+            Get
+                Return ResourceManager.GetString("ERR_TupleTooFewElements", resourceCulture)
+            End Get
+        End Property
+        
         '''<summary>
         '''  Looks up a localized string similar to Operator &apos;{0}&apos; must have two parameters..
         '''</summary>

src/Compilers/VisualBasic/Portable/VBResources.resx

@@ -5367,4 +5367,19 @@
   <data name="ERR_OptionMustBeAbsolutePath" xml:space="preserve">
     <value>Option '{0}' must be an absolute path.</value>
   </data>
+  <data name="ERR_TupleDuplicateMemberName" xml:space="preserve">
+    <value>Tuple member names must be unique.</value>
+  </data>
+  <data name="ERR_TupleExplicitNamesOnAllMembersOrNone" xml:space="preserve">
+    <value>Tuple member names must all be provided, if any one is provided.</value>
+  </data>
+  <data name="ERR_TupleReservedMemberName" xml:space="preserve">
+    <value>Tuple member name '{0}' is only allowed at position {1}.</value>
+  </data>
+  <data name="ERR_TupleReservedMemberNameAnyPosition" xml:space="preserve">
+    <value>Tuple membername '{0}' is disallowed at any position.</value>
+  </data>
+  <data name="ERR_TupleTooFewElements" xml:space="preserve">
+    <value>Tuple must contain at least two elements.</value>
+  </data>
 </root>

src/Compilers/VisualBasic/Test/Emit/BasicCompilerEmitTest.vbproj

@@ -98,6 +98,7 @@
     <Compile Include="CodeGen\CodeGenAsyncTests.vb" />
     <Compile Include="CodeGen\CodeGenClosureLambdaTests.vb" />
     <Compile Include="CodeGen\CodeGenCollectionInitializer.vb" />
+    <Compile Include="CodeGen\CodeGenTuples.vb" />
     <Compile Include="CodeGen\CodeGenConstLocal.vb" />
     <Compile Include="CodeGen\CodeGenDelegateCreation.vb" />
     <Compile Include="CodeGen\CodeGenEvents.vb" />

src/Compilers/VisualBasic/Test/Emit/CodeGen/CodeGenTuples.vb

+' Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+Imports Microsoft.CodeAnalysis
+Imports Microsoft.CodeAnalysis.Test.Utilities
+Imports Microsoft.CodeAnalysis.Text
+Imports Microsoft.CodeAnalysis.VisualBasic
+Imports Microsoft.CodeAnalysis.VisualBasic.Symbols
+Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
+Imports Microsoft.CodeAnalysis.VisualBasic.UnitTests.Emit
+Imports Roslyn.Test.Utilities
+
+Namespace Microsoft.CodeAnalysis.VisualBasic.UnitTests
+    Public Class CodeGenTuples
+        Inherits BasicTestBase
+
+        <Fact()>
+        Public Sub TupleTypeBinding()
+
+            Dim verifier = CompileAndVerify(
+<compilation>
+    <file name="a.vb">
+Imports System
+Module C
+
+    Sub Main()
+        Dim t as (Integer, Integer)
+        console.writeline(t)            
+    End Sub
+End Module
+
+Namespace System
+    Structure ValueTuple(Of T1, T2)
+        Public Overrides Function ToString() As String
+            Return "hello"
+        End Function
+    End Structure
+End Namespace
+
+    </file>
+</compilation>, expectedOutput:=<![CDATA[
+hello
+            ]]>)
+
+            verifier.VerifyIL("C.Main", <![CDATA[
+{
+  // Code size       12 (0xc)
+  .maxstack  1
+  .locals init (System.ValueTuple(Of Integer, Integer) V_0) //t
+  IL_0000:  ldloc.0
+  IL_0001:  box        "System.ValueTuple(Of Integer, Integer)"
+  IL_0006:  call       "Sub System.Console.WriteLine(Object)"
+  IL_000b:  ret
+}
+]]>)
+        End Sub
+
+        <Fact()>
+        Public Sub TupleFieldBinding()
+
+            Dim verifier = CompileAndVerify(
+<compilation>
+    <file name="a.vb">
+Imports System
+Module C
+
+    Sub Main()
+        Dim t as (Integer, Integer)
+
+        t.Item1 = 42
+        t.Item2 = t.Item1
+        console.writeline(t.Item2)            
+    End Sub
+End Module
+
+Namespace System
+    Structure ValueTuple(Of T1, T2)
+        Public Item1 As T1
+        Public Item2 As T2
+    End Structure
+End Namespace
+
+    </file>
+</compilation>, expectedOutput:=<![CDATA[
+42
+            ]]>)
+
+            verifier.VerifyIL("C.Main", <![CDATA[
+{
+  // Code size       34 (0x22)
+  .maxstack  2
+  .locals init (System.ValueTuple(Of Integer, Integer) V_0) //t
+  IL_0000:  ldloca.s   V_0
+  IL_0002:  ldc.i4.s   42
+  IL_0004:  stfld      "System.ValueTuple(Of Integer, Integer).Item1 As Integer"
+  IL_0009:  ldloca.s   V_0
+  IL_000b:  ldloc.0
+  IL_000c:  ldfld      "System.ValueTuple(Of Integer, Integer).Item1 As Integer"
+  IL_0011:  stfld      "System.ValueTuple(Of Integer, Integer).Item2 As Integer"
+  IL_0016:  ldloc.0
+  IL_0017:  ldfld      "System.ValueTuple(Of Integer, Integer).Item2 As Integer"
+  IL_001c:  call       "Sub System.Console.WriteLine(Integer)"
+  IL_0021:  ret
+}
+]]>)
+        End Sub
+
+        <Fact()>
+        Public Sub TupleNamedFieldBinding()
+
+            Dim verifier = CompileAndVerify(
+<compilation>
+    <file name="a.vb">
+Imports System
+Module C
+
+    Sub Main()
+        Dim t As (a As Integer, b As Integer)
+
+        t.a = 42
+        t.b = t.a
+
+        Console.WriteLine(t.b)
+    End Sub
+End Module
+
+Namespace System
+    Structure ValueTuple(Of T1, T2)
+        Public Item1 As T1
+        Public Item2 As T2
+    End Structure
+End Namespace
+
+    </file>
+</compilation>, expectedOutput:=<![CDATA[
+42
+            ]]>)
+
+            verifier.VerifyIL("C.Main", <![CDATA[
+{
+  // Code size       34 (0x22)
+  .maxstack  2
+  .locals init (System.ValueTuple(Of Integer, Integer) V_0) //t
+  IL_0000:  ldloca.s   V_0
+  IL_0002:  ldc.i4.s   42
+  IL_0004:  stfld      "System.ValueTuple(Of Integer, Integer).Item1 As Integer"
+  IL_0009:  ldloca.s   V_0
+  IL_000b:  ldloc.0
+  IL_000c:  ldfld      "System.ValueTuple(Of Integer, Integer).Item1 As Integer"
+  IL_0011:  stfld      "System.ValueTuple(Of Integer, Integer).Item2 As Integer"
+  IL_0016:  ldloc.0
+  IL_0017:  ldfld      "System.ValueTuple(Of Integer, Integer).Item2 As Integer"
+  IL_001c:  call       "Sub System.Console.WriteLine(Integer)"
+  IL_0021:  ret
+}
+]]>)
+        End Sub
+
+    End Class
+
+End Namespace
+