Create synthesized record constructor

src/Compilers/CSharp/Portable/Binder/BinderFactory.BinderFactoryVisitor.cs

@@ -643,8 +643,10 @@ private Binder VisitTypeDeclarationCore(TypeDeclarationSyntax parent)
 
                 // we are visiting type declarations fairly frequently
                 // and position is more likely to be in the body, so lets check for "inBody" first.
-                if (LookupPosition.IsBetweenTokens(_position, parent.OpenBraceToken, parent.CloseBraceToken) ||
-                    LookupPosition.IsInAttributeSpecification(_position, parent.AttributeLists))
+                if (parent.OpenBraceToken != default &&
+                    parent.CloseBraceToken != default &&
+                    (LookupPosition.IsBetweenTokens(_position, parent.OpenBraceToken, parent.CloseBraceToken) ||
+                     LookupPosition.IsInAttributeSpecification(_position, parent.AttributeLists)))
                 {
                     extraInfo = NodeUsage.NamedTypeBodyOrTypeParameters;
                 }
@@ -654,7 +656,7 @@ private Binder VisitTypeDeclarationCore(TypeDeclarationSyntax parent)
                 }
                 else if (LookupPosition.IsBetweenTokens(_position, parent.Keyword, parent.OpenBraceToken))
                 {
-                    extraInfo = NodeUsage.NamedTypeBaseList;
+                    extraInfo = NodeUsage.NamedTypeBaseListOrParameterList;
                 }
 
                 return VisitTypeDeclarationCore(parent, extraInfo);
@@ -679,7 +681,7 @@ private Binder VisitTypeDeclarationCore(TypeDeclarationSyntax parent, NodeUsage
                     {
                         var typeSymbol = ((NamespaceOrTypeSymbol)resultBinder.ContainingMemberOrLambda).GetSourceTypeMember(parent);
 
-                        if (extraInfo == NodeUsage.NamedTypeBaseList)
+                        if (extraInfo == NodeUsage.NamedTypeBaseListOrParameterList)
                         {
                             // even though there could be no type parameter, we need this binder 
                             // for its "IsAccessible"

src/Compilers/CSharp/Portable/Binder/BinderFactory.NodeUsage.cs

@@ -15,7 +15,7 @@ internal enum NodeUsage : byte
             OperatorBody = 1 << 0,
 
             NamedTypeBodyOrTypeParameters = 1 << 0,
-            NamedTypeBaseList = 1 << 1,
+            NamedTypeBaseListOrParameterList = 1 << 1,
 
             NamespaceBody = 1 << 0,
             NamespaceUsings = 1 << 1,

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -5930,4 +5930,7 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
   <data name="IDS_FeatureRecords" xml:space="preserve">
     <value>records</value>
   </data>
+  <data name="ERR_BadRecordDeclaration" xml:space="preserve">
+    <value>Records must have both a 'data' modifier and parameter list</value>
+  </data>
 </root>

src/Compilers/CSharp/Portable/Errors/ErrorCode.cs

@@ -1738,6 +1738,7 @@ internal enum ErrorCode
         ERR_InternalError = 8751,
 
         ERR_ExternEventInitializer = 8760,
+        ERR_BadRecordDeclaration = 8761,
 
         // Note: you will need to re-generate compiler code after adding warnings (eng\generate-compiler-code.cmd)
     }

src/Compilers/CSharp/Portable/Symbols/Synthesized/SynthesizedRecordConstructor.cs

@@ -0,0 +1,32 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+#nullable enable
+
+using System.Collections.Immutable;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace Microsoft.CodeAnalysis.CSharp.Symbols
+{
+    internal sealed class SynthesizedRecordConstructor : SynthesizedInstanceConstructor
+    {
+        public override ImmutableArray<ParameterSymbol> Parameters { get; }
+
+        public SynthesizedRecordConstructor(
+            NamedTypeSymbol containingType,
+            Binder parameterBinder,
+            ParameterListSyntax parameterList,
+            DiagnosticBag diagnostics)
+            : base(containingType)
+        {
+            Parameters = ParameterHelpers.MakeParameters(
+                parameterBinder,
+                this,
+                parameterList,
+                out _,
+                diagnostics,
+                allowRefOrOut: true,
+                allowThis: false,
+                addRefReadOnlyModifier: false);
+        }
+    }
+}

src/Compilers/CSharp/Portable/Symbols/Tuples/TupleTypeSymbol.cs

@@ -567,7 +567,7 @@ public sealed override ImmutableArray<FieldSymbol> TupleElements
             return IsTupleType ? TupleData!.GetTupleMemberSymbolForUnderlyingMember(underlyingMemberOpt) : default;
         }
 
-        protected ArrayBuilder<Symbol>? AddOrWrapTupleMembers(ImmutableArray<Symbol> currentMembers)
+        protected ArrayBuilder<Symbol> AddOrWrapTupleMembers(ImmutableArray<Symbol> currentMembers)
         {
             Debug.Assert(IsTupleType);
             Debug.Assert(currentMembers.All(m => !(m is TupleVirtualElementFieldSymbol)));

src/Compilers/CSharp/Portable/Syntax/LookupPosition.cs

@@ -118,6 +118,9 @@ internal static bool IsInParameterList(int position, BaseMethodDeclarationSyntax
             return IsBeforeToken(position, parameterList, parameterList.CloseParenToken);
         }
 
+        internal static bool IsInParameterList(int position, ParameterListSyntax parameterList)
+            => parameterList != null && IsBeforeToken(position, parameterList, parameterList.CloseParenToken);
+
         internal static bool IsInMethodDeclaration(int position, BaseMethodDeclarationSyntax methodDecl)
         {
             Debug.Assert(methodDecl != null);

src/Compilers/CSharp/Portable/xlf/CSharpResources.cs.xlf

@@ -82,6 +82,11 @@
         <target state="translated">Neplatný operand pro porovnávací vzorek. Vyžaduje se hodnota, ale nalezeno: {0}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.de.xlf

@@ -82,6 +82,11 @@
         <target state="translated">Ungültiger Operand für die Musterübereinstimmung. Ein Wert ist erforderlich, gefunden wurde aber "{0}".</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.es.xlf

@@ -82,6 +82,11 @@
         <target state="translated">Operando no válido para la coincidencia de patrones. Se requería un valor, pero se encontró '{0}'.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.fr.xlf

@@ -82,6 +82,11 @@
         <target state="translated">Opérande non valide pour les critères spéciaux ; la valeur nécessaire n'est pas celle trouvée, '{0}'.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.it.xlf

@@ -82,6 +82,11 @@
         <target state="translated">L'operando non è valido per i criteri di ricerca. È richiesto un valore ma è stato trovato '{0}'.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.ja.xlf

@@ -82,6 +82,11 @@
         <target state="translated">パターン マッチには使用できないオペランドです。値が必要ですが、'{0}' が見つかりました。</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.ko.xlf

@@ -82,6 +82,11 @@
         <target state="translated">패턴 일치에 대한 피연산자가 잘못되었습니다. 값이 필요하지만 '{0}'을(를) 찾았습니다.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.pl.xlf

@@ -82,6 +82,11 @@
         <target state="translated">Nieprawidłowy operand dla dopasowania wzorca; wymagana jest wartość, a znaleziono „{0}”.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.pt-BR.xlf

@@ -82,6 +82,11 @@
         <target state="translated">Operando inválido para correspondência de padrão. Um valor era obrigatório, mas '{0}' foi encontrado.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.ru.xlf

@@ -82,6 +82,11 @@
         <target state="translated">Недопустимый операнд для сопоставления с шаблоном. Требуется значение, но найдено "{0}".</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.tr.xlf

@@ -82,6 +82,11 @@
         <target state="translated">Desen eşleşmesi için işlenen geçersiz. Değer gerekiyordu ancak '{0}' bulundu.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.zh-Hans.xlf

@@ -82,6 +82,11 @@
         <target state="translated">用于模式匹配的操作数无效；需要值，但找到的是“{0}”。</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.zh-Hant.xlf

@@ -82,6 +82,11 @@
         <target state="translated">模式比對運算元無效; 需要值，但找到 '{0}'。</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_BadRecordDeclaration">
+        <source>Records must have both a 'data' modifier and parameter list</source>
+        <target state="new">Records must have both a 'data' modifier and parameter list</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_BadSwitchValue">
         <source>Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</source>
         <target state="new">Command-line syntax error: '{0}' is not a valid value for the '{1}' option. The value must be of the form '{2}'.</target>

src/Compilers/CSharp/Test/Semantic/Semantics/LookupPositionTests.cs

@@ -22,6 +22,47 @@ public class LookupPositionTests : CompilingTestBase
     {
         private const char KeyPositionMarker = '`';
 
+        [Fact]
+        public void PositionalRecord1()
+        {
+            var text = @"
+class C(int x, int y);";
+            var expectedNames = MakeExpectedSymbols(
+                Add( // Global
+                    "System",
+                    "Microsoft",
+                    "C"));
+
+            TestLookupNames(text, expectedNames);
+        }
+
+        [Fact]
+        public void PositionalRecord2()
+        {
+            var text = @"
+`class C`<T`>(int x, T t = default(T));";
+            var expectedNames = MakeExpectedSymbols(
+                Add( // Global
+                    "System",
+                    "Microsoft",
+                    "C<T>"),
+                Add( // C Type parameters
+                    "T"),
+                Add( // Members
+                    "System.Boolean System.Object.Equals(System.Object obj)",
+                    "System.Boolean System.Object.Equals(System.Object objA, System.Object objB)",
+                    "System.Boolean System.Object.ReferenceEquals(System.Object objA, System.Object objB)",
+                    "System.Int32 System.Object.GetHashCode()",
+                    "System.Object System.Object.MemberwiseClone()",
+                    "void System.Object.Finalize()",
+                    "System.String System.Object.ToString()",
+                    "System.Type System.Object.GetType()"),
+                s_pop
+                );
+
+            TestLookupNames(text, expectedNames);
+        }
+
         [Fact]
         public void ExpressionBodiedProp()
         {