Merge pull request #4321 from AlekseyTs/Issue4028

Handle MemberBindingExpression in Binder.GetEventSymbol

src/Compilers/CSharp/Portable/Binder/Binder_Statements.cs

@@ -1559,6 +1559,9 @@ private static EventSymbol GetEventSymbol(BoundExpression expr, out BoundExpress
                 case SyntaxKind.IdentifierName:
                     eventSyntax = syntax;
                     break;
+                case SyntaxKind.MemberBindingExpression:
+                    eventSyntax = ((MemberBindingExpressionSyntax)syntax).Name;
+                    break;
                 default:
                     throw ExceptionUtilities.UnexpectedValue(syntax.Kind());
             }

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

@@ -1248,5 +1248,157 @@ interface I<in T, out U> {{ }}";
                 }
             }
         }
+
+
+        [Fact, WorkItem(4028, "https://github.com/dotnet/roslyn/issues/4028")]
+        public void ConditionalAccessToEvent_01()
+        {
+            string source = @"
+using System;
+
+class TestClass
+{
+    event Action test;
+
+    public static void Test(TestClass receiver)
+    {
+        Console.WriteLine(receiver?.test);
+    }
+
+    static void Main()
+    {
+        Console.WriteLine(""----"");
+        Test(null);
+        Console.WriteLine(""----"");
+        Test(new TestClass() {test = Main});
+        Console.WriteLine(""----"");
+    }
+}
+";
+
+            var compilation = CreateCompilationWithMscorlib(source, options: TestOptions.DebugExe);
+
+            CompileAndVerify(compilation, expectedOutput: 
+@"----
+
+----
+System.Action
+----");
+
+            var tree = compilation.SyntaxTrees.Single();
+            var memberBinding = tree.GetRoot().DescendantNodes().OfType<MemberBindingExpressionSyntax>().Single();
+            var access = (ConditionalAccessExpressionSyntax)memberBinding.Parent;
+
+            Assert.Equal(".test", memberBinding.ToString());
+            Assert.Equal("receiver?.test", access.ToString());
+
+            var model = compilation.GetSemanticModel(tree);
+
+            Assert.Equal("event System.Action TestClass.test", model.GetSymbolInfo(memberBinding).Symbol.ToTestDisplayString());
+            Assert.Equal("event System.Action TestClass.test", model.GetSymbolInfo(memberBinding.Name).Symbol.ToTestDisplayString());
+
+            Assert.Null(model.GetSymbolInfo(access).Symbol);
+        }
+
+        [Fact, WorkItem(4028, "https://github.com/dotnet/roslyn/issues/4028")]
+        public void ConditionalAccessToEvent_02()
+        {
+            string source = @"
+using System;
+
+class TestClass
+{
+    event Action test;
+
+    public static void Test(TestClass receiver)
+    {
+        receiver?.test();
+    }
+
+    static void Main()
+    {
+        Console.WriteLine(""----"");
+        Test(null);
+        Console.WriteLine(""----"");
+        Test(new TestClass() {test = Target});
+        Console.WriteLine(""----"");
+    }
+
+    static void Target()
+    {
+        Console.WriteLine(""Target"");
+    }
+}
+";
+
+            var compilation = CreateCompilationWithMscorlib(source, options: TestOptions.DebugExe);
+
+            CompileAndVerify(compilation, expectedOutput:
+@"----
+----
+Target
+----");
+
+            var tree = compilation.SyntaxTrees.Single();
+            var memberBinding = tree.GetRoot().DescendantNodes().OfType<MemberBindingExpressionSyntax>().Single();
+            var invocation = (InvocationExpressionSyntax)memberBinding.Parent;
+            var access = (ConditionalAccessExpressionSyntax)invocation.Parent;
+
+            Assert.Equal(".test", memberBinding.ToString());
+            Assert.Equal(".test()", invocation.ToString());
+            Assert.Equal("receiver?.test()", access.ToString());
+
+            var model = compilation.GetSemanticModel(tree);
+
+            Assert.Equal("event System.Action TestClass.test", model.GetSymbolInfo(memberBinding).Symbol.ToTestDisplayString());
+            Assert.Equal("event System.Action TestClass.test", model.GetSymbolInfo(memberBinding.Name).Symbol.ToTestDisplayString());
+            Assert.Equal("void System.Action.Invoke()", model.GetSymbolInfo(invocation).Symbol.ToTestDisplayString());
+
+            Assert.Null(model.GetSymbolInfo(access).Symbol);
+        }
+
+        [Fact, WorkItem(4028, "https://github.com/dotnet/roslyn/issues/4028")]
+        public void ConditionalAccessToEvent_03()
+        {
+            string source = @"
+using System;
+
+class TestClass
+{
+    event Action test;
+
+    public static void Test(TestClass receiver)
+    {
+        receiver?.test += Main;
+    }
+
+    static void Main()
+    {
+    }
+}
+";
+
+            var compilation = CreateCompilationWithMscorlib(source, options: TestOptions.DebugDll);
+
+            compilation.VerifyDiagnostics(
+    // (10,9): error CS0131: The left-hand side of an assignment must be a variable, property or indexer
+    //         receiver?.test += Main;
+    Diagnostic(ErrorCode.ERR_AssgLvalueExpected, "receiver?.test").WithLocation(10, 9)
+                );
+
+            var tree = compilation.SyntaxTrees.Single();
+            var memberBinding = tree.GetRoot().DescendantNodes().OfType<MemberBindingExpressionSyntax>().Single();
+            var access = (ConditionalAccessExpressionSyntax)memberBinding.Parent;
+
+            Assert.Equal(".test", memberBinding.ToString());
+            Assert.Equal("receiver?.test", access.ToString());
+
+            var model = compilation.GetSemanticModel(tree);
+
+            Assert.Equal("event System.Action TestClass.test", model.GetSymbolInfo(memberBinding).Symbol.ToTestDisplayString());
+            Assert.Equal("event System.Action TestClass.test", model.GetSymbolInfo(memberBinding.Name).Symbol.ToTestDisplayString());
+
+            Assert.Null(model.GetSymbolInfo(access).Symbol);
+        }
     }
 }

src/Compilers/VisualBasic/Test/Semantic/Semantics/ConditionalAccessTests.vb

@@ -9241,5 +9241,196 @@ M3
 ]]>)
         End Sub
 
+        <Fact(), WorkItem(4028, "https://github.com/dotnet/roslyn/issues/4028")>
+        Public Sub ConditionalAccessToEvent_01()
+
+            Dim compilationDef =
+<compilation>
+    <file name="a.vb"><![CDATA[
+Imports System
+
+Class TestClass
+
+    Event TestEvent As Action
+
+    Sub Main(receiver As TestClass)
+        Console.WriteLine(receiver?.TestEvent)
+    End Sub
+
+End Class
+    ]]></file>
+</compilation>
+
+            Dim compilation = CompilationUtils.CreateCompilationWithMscorlib(compilationDef)
+
+            compilation.AssertTheseDiagnostics(<expected>
+BC32022: 'Public Event TestEvent As Action' is an event, and cannot be called directly. Use a 'RaiseEvent' statement to raise an event.
+        Console.WriteLine(receiver?.TestEvent)
+                                   ~~~~~~~~~~
+                                               </expected>)
+
+            Dim tree = compilation.SyntaxTrees.Single()
+            Dim access = tree.GetRoot().DescendantNodes().OfType(Of ConditionalAccessExpressionSyntax)().Single()
+            Dim memberBinding = DirectCast(access.WhenNotNull, MemberAccessExpressionSyntax)
+
+            Assert.Equal(".TestEvent", memberBinding.ToString())
+            Assert.Equal("receiver?.TestEvent", access.ToString())
+
+            Dim model = compilation.GetSemanticModel(tree)
+
+            Dim info = model.GetSymbolInfo(memberBinding)
+            Assert.Equal(CandidateReason.NotAValue, info.CandidateReason)
+            Assert.Equal("Event TestClass.TestEvent As System.Action", info.CandidateSymbols.Single().ToTestDisplayString())
+
+            info = model.GetSymbolInfo(memberBinding.Name)
+            Assert.Equal(CandidateReason.NotAValue, info.CandidateReason)
+            Assert.Equal("Event TestClass.TestEvent As System.Action", info.CandidateSymbols.Single().ToTestDisplayString())
+
+            info = model.GetSymbolInfo(access)
+            Assert.Null(info.Symbol)
+            Assert.False(info.CandidateSymbols.Any())
+        End Sub
+
+        <Fact(), WorkItem(4028, "https://github.com/dotnet/roslyn/issues/4028")>
+        Public Sub ConditionalAccessToEvent_02()
+
+            Dim compilationDef =
+<compilation>
+    <file name="a.vb"><![CDATA[
+Imports System
+
+Class TestClass
+
+    Event TestEvent As Action
+
+    Shared Sub Test(receiver As TestClass)
+        RaiseEvent receiver?.TestEvent
+    End Sub
+End Class
+    ]]></file>
+</compilation>
+
+            Dim compilation = CompilationUtils.CreateCompilationWithMscorlib(compilationDef)
+
+            compilation.AssertTheseDiagnostics(<expected>
+BC30451: 'receiver' is not declared. It may be inaccessible due to its protection level.
+        RaiseEvent receiver?.TestEvent
+                   ~~~~~~~~
+BC30205: End of statement expected.
+        RaiseEvent receiver?.TestEvent
+                           ~
+                                               </expected>)
+
+            Dim tree = compilation.SyntaxTrees.Single()
+            Assert.False(tree.GetRoot().DescendantNodes().OfType(Of ConditionalAccessExpressionSyntax)().Any())
+        End Sub
+
+        <Fact(), WorkItem(4028, "https://github.com/dotnet/roslyn/issues/4028")>
+        Public Sub ConditionalAccessToEvent_03()
+
+            Dim compilationDef =
+<compilation>
+    <file name="a.vb"><![CDATA[
+Imports System
+
+Class TestClass
+
+    Event TestEvent As Action
+
+    Shared Sub Test(receiver As TestClass)
+        AddHandler receiver?.TestEvent, AddressOf Main
+    End Sub
+
+    Shared Sub Main()
+    End Sub
+End Class
+    ]]></file>
+</compilation>
+
+            Dim compilation = CompilationUtils.CreateCompilationWithMscorlib(compilationDef)
+
+            compilation.AssertTheseDiagnostics(<expected>
+BC30677: 'AddHandler' or 'RemoveHandler' statement event operand must be a dot-qualified expression or a simple name.
+        AddHandler receiver?.TestEvent, AddressOf Main
+                   ~~~~~~~~~~~~~~~~~~~
+                                               </expected>)
+
+            Dim tree = compilation.SyntaxTrees.Single()
+            Dim access = tree.GetRoot().DescendantNodes().OfType(Of ConditionalAccessExpressionSyntax)().Single()
+            Dim memberBinding = DirectCast(access.WhenNotNull, MemberAccessExpressionSyntax)
+
+            Assert.Equal(".TestEvent", memberBinding.ToString())
+            Assert.Equal("receiver?.TestEvent", access.ToString())
+
+            Dim model = compilation.GetSemanticModel(tree)
+
+            Dim info = model.GetSymbolInfo(memberBinding)
+            Assert.Equal(CandidateReason.NotAValue, info.CandidateReason)
+            Assert.Equal("Event TestClass.TestEvent As System.Action", info.CandidateSymbols.Single().ToTestDisplayString())
+
+            info = model.GetSymbolInfo(memberBinding.Name)
+            Assert.Equal(CandidateReason.NotAValue, info.CandidateReason)
+            Assert.Equal("Event TestClass.TestEvent As System.Action", info.CandidateSymbols.Single().ToTestDisplayString())
+
+            info = model.GetSymbolInfo(access)
+            Assert.Null(info.Symbol)
+            Assert.False(info.CandidateSymbols.Any())
+        End Sub
+
+        <Fact(), WorkItem(4028, "https://github.com/dotnet/roslyn/issues/4028")>
+        Public Sub ConditionalAccessToEvent_04()
+
+            Dim compilationDef =
+<compilation>
+    <file name="a.vb"><![CDATA[
+Imports System
+
+Class TestClass
+
+    Event TestEvent As Action
+
+    Shared Sub Test(receiver As TestClass)
+        receiver?.TestEvent()
+    End Sub
+End Class
+    ]]></file>
+</compilation>
+
+            Dim compilation = CompilationUtils.CreateCompilationWithMscorlib(compilationDef)
+
+            compilation.AssertTheseDiagnostics(<expected>
+BC32022: 'Public Event TestEvent As Action' is an event, and cannot be called directly. Use a 'RaiseEvent' statement to raise an event.
+        receiver?.TestEvent()
+                 ~~~~~~~~~~
+                                               </expected>)
+
+            Dim tree = compilation.SyntaxTrees.Single()
+            Dim access = tree.GetRoot().DescendantNodes().OfType(Of ConditionalAccessExpressionSyntax)().Single()
+            Dim invocation = DirectCast(access.WhenNotNull, InvocationExpressionSyntax)
+            Dim memberBinding = DirectCast(invocation.Expression, MemberAccessExpressionSyntax)
+
+            Assert.Equal(".TestEvent", memberBinding.ToString())
+            Assert.Equal(".TestEvent()", invocation.ToString())
+            Assert.Equal("receiver?.TestEvent()", access.ToString())
+
+            Dim model = compilation.GetSemanticModel(tree)
+
+            Dim info = model.GetSymbolInfo(memberBinding)
+            Assert.Equal(CandidateReason.NotAValue, info.CandidateReason)
+            Assert.Equal("Event TestClass.TestEvent As System.Action", info.CandidateSymbols.Single().ToTestDisplayString())
+
+            info = model.GetSymbolInfo(memberBinding.Name)
+            Assert.Equal(CandidateReason.NotAValue, info.CandidateReason)
+            Assert.Equal("Event TestClass.TestEvent As System.Action", info.CandidateSymbols.Single().ToTestDisplayString())
+
+            info = model.GetSymbolInfo(invocation)
+            Assert.Null(info.Symbol)
+            Assert.False(info.CandidateSymbols.Any())
+
+            info = model.GetSymbolInfo(access)
+            Assert.Null(info.Symbol)
+            Assert.False(info.CandidateSymbols.Any())
+        End Sub
+
     End Class
 End Namespace
\ No newline at end of file