Account for delegate creation inside an explicitly-converted tuple ex…

…pression (#64882)

Fixes #64774.

src/Compilers/CSharp/Portable/Operations/CSharpOperationFactory.cs

@@ -1037,6 +1037,14 @@ private IOperation CreateBoundConversionOperation(BoundConversion boundConversio
                 // overload resolution succeeded. The resulting method could be invalid for other reasons, but we don't
                 // hide the resolved method.
                 IOperation target = CreateDelegateTargetOperation(boundConversion);
+
+                // If this was an explicit tuple expression conversion, such as ((Action, int))(M, 1), we will be "explicit", because the
+                // original conversion was explicit in code, but the syntax node for this delegate creation and the nested method group will
+                // be the same. We therefore need to mark this node as implicit to ensure we don't have two explicit nodes for the same syntax.
+                Debug.Assert(isImplicit || target.Syntax != syntax || target.IsImplicit || boundConversion.ConversionGroupOpt != null);
+
+                isImplicit = isImplicit || (target.Syntax == syntax && !target.IsImplicit);
+
                 return new DelegateCreationOperation(target, _semanticModel, syntax, type, isImplicit);
             }
             else

src/Compilers/CSharp/Test/IOperation/IOperation/IOperationTests_IDelegateCreationExpression.cs

@@ -1998,5 +1998,76 @@ void M(Action a1, Action a2, Action a3)
 
             VerifyFlowGraphAndDiagnosticsForTest<BlockSyntax>(source, expectedFlowGraph, expectedDiagnostics);
         }
+
+        [Fact, WorkItem(64774, "https://github.com/dotnet/roslyn/issues/64774")]
+        public void ExplicitCastOnTuple_01()
+        {
+            var code = """
+                using System;
+
+                (int i, Action invoke) = /*<bind>*/((int, Action))(1, M)/*</bind>*/;
+
+                void M() {}
+                """;
+
+            var expectedOperationTree = """
+IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: (System.Int32, System.Action)) (Syntax: '((int, Action))(1, M)')
+  Conversion: CommonConversion (Exists: True, IsIdentity: False, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+  Operand:
+    ITupleOperation (OperationKind.Tuple, Type: (System.Int32, System.Action M)) (Syntax: '(1, M)')
+      NaturalType: null
+      Elements(2):
+          IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: System.Int32, Constant: 1, IsImplicit) (Syntax: '1')
+            Conversion: CommonConversion (Exists: True, IsIdentity: True, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+            Operand:
+              ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
+          IDelegateCreationOperation (OperationKind.DelegateCreation, Type: System.Action, IsImplicit) (Syntax: 'M')
+            Target:
+              IMethodReferenceOperation: void M() (OperationKind.MethodReference, Type: null) (Syntax: 'M')
+                Instance Receiver:
+                  IInstanceReferenceOperation (ReferenceKind: ContainingTypeInstance) (OperationKind.InstanceReference, Type: Program, IsImplicit) (Syntax: 'M')
+""";
+            VerifyOperationTreeAndDiagnosticsForTest<CastExpressionSyntax>(code, expectedOperationTree, DiagnosticDescription.None);
+        }
+
+        [Fact, WorkItem(64774, "https://github.com/dotnet/roslyn/issues/64774")]
+        public void ExplicitCastOnTuple_02()
+        {
+            var code = """
+                unsafe
+                {
+                    (int i, delegate*<void> invoke) = /*<bind>*/((int, delegate*<void>))(1, &M)/*</bind>*/;
+                }
+
+                static void M() {}
+                """;
+
+            var comp = CreateCompilation(code, options: TestOptions.UnsafeReleaseExe);
+            comp.VerifyDiagnostics(
+                // (3,56): error CS0306: The type 'delegate*<void>' may not be used as a type argument
+                //     (int i, delegate*<void> invoke) = /*<bind>*/((int, delegate*<void>))(1, &M)/*</bind>*/;
+                Diagnostic(ErrorCode.ERR_BadTypeArgument, "delegate*<void>").WithArguments("delegate*<void>").WithLocation(3, 56)
+            );
+
+            var expectedOperationTree = """
+IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: (System.Int32, delegate*<System.Void>), IsInvalid) (Syntax: '((int, dele ... d>))(1, &M)')
+  Conversion: CommonConversion (Exists: True, IsIdentity: True, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+  Operand:
+    ITupleOperation (OperationKind.Tuple, Type: (System.Int32, delegate*<System.Void>)) (Syntax: '(1, &M)')
+      NaturalType: null
+      Elements(2):
+          IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: System.Int32, Constant: 1, IsImplicit) (Syntax: '1')
+            Conversion: CommonConversion (Exists: True, IsIdentity: True, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+            Operand:
+              ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
+          IAddressOfOperation (OperationKind.AddressOf, Type: delegate*<System.Void>) (Syntax: '&M')
+            Reference:
+              IMethodReferenceOperation: void M() (Static) (OperationKind.MethodReference, Type: null) (Syntax: 'M')
+                Instance Receiver:
+                  null
+""";
+
+            VerifyOperationTreeForTest<CastExpressionSyntax>(comp, expectedOperationTree);
+        }
     }
 }

src/Compilers/VisualBasic/Test/IOperation/IOperation/IOperationTests_IDelegateCreationExpression.vb

@@ -4401,6 +4401,44 @@ IDelegateCreationOperation (OperationKind.DelegateCreation, Type: System.Action)
             VerifyOperationTreeAndDiagnosticsForTest(Of TryCastExpressionSyntax)(source, expectedOperationTree, expectedDiagnostics)
         End Sub
 
+        <CompilerTrait(CompilerFeature.IOperation)>
+        <Fact()>
+        Public Sub ExplicitCastOnTuple()
+            Dim source = <![CDATA[
+Imports System
+
+Public Class C
+    Public Sub M1()
+        Dim x = DirectCast((AddressOf M2, 1), (Action, Integer))'BIND:"DirectCast((AddressOf M2, 1), (Action, Integer))"
+    End Sub
+
+    Public Sub M2()
+    End Sub
+End Class]]>.Value
+
+            Dim expectedOperationTree = <![CDATA[
+IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: (System.Action, System.Int32)) (Syntax: 'DirectCast( ... , Integer))')
+  Conversion: CommonConversion (Exists: True, IsIdentity: True, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+  Operand:
+    ITupleOperation (OperationKind.Tuple, Type: (System.Action, System.Int32)) (Syntax: '(AddressOf M2, 1)')
+      NaturalType: null
+      Elements(2):
+          IDelegateCreationOperation (OperationKind.DelegateCreation, Type: System.Action, IsImplicit) (Syntax: 'AddressOf M2')
+            Target:
+              IMethodReferenceOperation: Sub C.M2() (OperationKind.MethodReference, Type: null) (Syntax: 'AddressOf M2')
+                Instance Receiver:
+                  IInstanceReferenceOperation (ReferenceKind: ContainingTypeInstance) (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'M2')
+          IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: System.Int32, Constant: 1, IsImplicit) (Syntax: '1')
+            Conversion: CommonConversion (Exists: True, IsIdentity: True, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+            Operand:
+              ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
+]]>.Value
+
+            Dim expectedDiagnostics = String.Empty
+
+            VerifyOperationTreeAndDiagnosticsForTest(Of DirectCastExpressionSyntax)(source, expectedOperationTree, expectedDiagnostics)
+        End Sub
+
 #End Region
 
 #Region "Anonymous Delegates"