Allow declaring iterator in records (#46713) (#46751)

Co-authored-by: NYair Halberstadt <yairhalberstadt@gmail.com>

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

@@ -27,7 +27,7 @@ internal sealed class SourceConstructorSymbol : SourceConstructorSymbolBase
              ConstructorDeclarationSyntax syntax,
              MethodKind methodKind,
              DiagnosticBag diagnostics) :
-             base(containingType, location, syntax)
+             base(containingType, location, syntax, SyntaxFacts.HasYieldOperations(syntax))
         {
             bool hasBlockBody = syntax.Body != null;
             _isExpressionBodied = !hasBlockBody && syntax.ExpressionBody != null;

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

@@ -19,8 +19,9 @@ internal abstract class SourceConstructorSymbolBase : SourceMemberMethodSymbol
         protected SourceConstructorSymbolBase(
             SourceMemberContainerTypeSymbol containingType,
             Location location,
-            CSharpSyntaxNode syntax)
-            : base(containingType, syntax.GetReference(), ImmutableArray.Create(location), SyntaxFacts.HasYieldOperations(syntax))
+            CSharpSyntaxNode syntax,
+            bool isIterator)
+            : base(containingType, syntax.GetReference(), ImmutableArray.Create(location), isIterator)
         {
             Debug.Assert(
                 syntax.IsKind(SyntaxKind.ConstructorDeclaration) ||

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

@@ -15,7 +15,7 @@ internal sealed class SynthesizedRecordConstructor : SourceConstructorSymbolBase
              SourceMemberContainerTypeSymbol containingType,
              RecordDeclarationSyntax syntax,
              DiagnosticBag diagnostics) :
-             base(containingType, syntax.ParameterList!.GetLocation(), syntax)
+             base(containingType, syntax.ParameterList!.GetLocation(), syntax, isIterator: false)
         {
             this.MakeFlags(MethodKind.Constructor, containingType.IsAbstract ? DeclarationModifiers.Protected : DeclarationModifiers.Public, returnsVoid: true, isExtensionMethod: false);
         }

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

@@ -4,6 +4,7 @@
 
 #nullable enable
 
+using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using Microsoft.CodeAnalysis;
@@ -550,7 +551,11 @@ internal static bool HasYieldOperations(SyntaxNode? node)
         {
             // Do not descend into functions and expressions
             return node is object &&
-                   node.DescendantNodesAndSelf(child => !IsNestedFunction(child) && !(node is ExpressionSyntax)).Any(n => n is YieldStatementSyntax);
+                   node.DescendantNodesAndSelf(child =>
+                   {
+                       Debug.Assert(ReferenceEquals(node, child) || child is not (MemberDeclarationSyntax or TypeDeclarationSyntax));
+                       return !IsNestedFunction(child) && !(node is ExpressionSyntax);
+                   }).Any(n => n is YieldStatementSyntax);
         }
 
         internal static bool HasReturnWithExpression(SyntaxNode? node)

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

@@ -22198,5 +22198,30 @@ private void Handle3(SymbolAnalysisContext context)
                 }
             }
         }
+
+        [Fact]
+        [WorkItem(46657, "https://github.com/dotnet/roslyn/issues/46657")]
+        public void CanDeclareIteratorInRecord()
+        {
+            var source = @"
+using System.Collections.Generic;
+
+public record X(int a)
+{
+    public static void Main()
+    {
+        foreach(var i in new X(42).GetItems())
+        {
+            System.Console.Write(i);
+        }
+    }
+    public IEnumerable<int> GetItems() { yield return a; yield return a + 1; }
+}";
+
+            var comp = CreateCompilation(new[] { source, IsExternalInitTypeDefinition }, options: TestOptions.DebugExe, parseOptions: TestOptions.RegularPreview)
+                .VerifyDiagnostics();
+
+            CompileAndVerify(comp, expectedOutput: "4243", verify: Verification.Skipped /* init-only */);
+        }
     }
 }