Bind expression variables appearing in a goto case statement. (#41709)

* Bind expression variables appearing in a goto case statement.
Fixes #40714

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

@@ -46,6 +46,7 @@ internal abstract class ExpressionVariableFinder<TFieldOrLocalSymbol> : CSharpSy
                 case SyntaxKind.VariableDeclarator:
                 case SyntaxKind.ConstructorDeclaration:
                 case SyntaxKind.SwitchExpressionArm:
+                case SyntaxKind.GotoCaseStatement:
                     break;
                 case SyntaxKind.ArgumentList:
                     Debug.Assert(node.Parent is ConstructorInitializerSyntax);
@@ -99,6 +100,12 @@ public override void VisitVariableDeclarator(VariableDeclaratorSyntax node)
             VisitNodeToBind(node.Initializer);
         }
 
+        public override void VisitGotoStatement(GotoStatementSyntax node)
+        {
+            if (node.Kind() == SyntaxKind.GotoCaseStatement)
+                Visit(node.Expression);
+        }
+
         private void VisitNodeToBind(CSharpSyntaxNode node)
         {
             SyntaxNode previousNodeToBind = _nodeToBind;

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

@@ -247,6 +247,7 @@ protected ImmutableArray<LocalSymbol> BuildLocals(SyntaxList<StatementSyntax> st
                     case SyntaxKind.YieldReturnStatement:
                     case SyntaxKind.ReturnStatement:
                     case SyntaxKind.ThrowStatement:
+                    case SyntaxKind.GotoCaseStatement:
                         ExpressionVariableFinder.FindExpressionVariables(this, locals, innerStatement, enclosingBinder.GetBinder(innerStatement) ?? enclosingBinder);
                         break;
 

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

@@ -171,6 +171,7 @@ internal override string GetDebuggerDisplay()
                 nodeToBind.Kind() == SyntaxKind.BaseConstructorInitializer ||
                 nodeToBind.Kind() == SyntaxKind.SwitchExpressionArm ||
                 nodeToBind.Kind() == SyntaxKind.ArgumentList && nodeToBind.Parent is ConstructorInitializerSyntax ||
+                nodeToBind.Kind() == SyntaxKind.GotoCaseStatement || // for error recovery
                 nodeToBind.Kind() == SyntaxKind.VariableDeclarator &&
                     new[] { SyntaxKind.LocalDeclarationStatement, SyntaxKind.ForStatement, SyntaxKind.UsingStatement, SyntaxKind.FixedStatement }.
                         Contains(nodeToBind.Ancestors().OfType<StatementSyntax>().First().Kind()) ||
@@ -742,6 +743,7 @@ private class LocalSymbolWithEnclosingContext : SourceLocalSymbol
                     nodeToBind.Kind() == SyntaxKind.ArgumentList && nodeToBind.Parent is ConstructorInitializerSyntax ||
                     nodeToBind.Kind() == SyntaxKind.VariableDeclarator ||
                     nodeToBind.Kind() == SyntaxKind.SwitchExpressionArm ||
+                    nodeToBind.Kind() == SyntaxKind.GotoCaseStatement ||
                     nodeToBind is ExpressionSyntax);
                 Debug.Assert(!(nodeToBind.Kind() == SyntaxKind.SwitchExpressionArm) || nodeBinder is SwitchExpressionArmBinder);
                 this._nodeBinder = nodeBinder;
@@ -783,6 +785,9 @@ protected override TypeWithAnnotations InferTypeOfVarVariable(DiagnosticBag diag
                         var armBinder = (SwitchExpressionArmBinder)_nodeBinder;
                         armBinder.BindSwitchExpressionArm(arm, diagnostics);
                         break;
+                    case SyntaxKind.GotoCaseStatement:
+                        _nodeBinder.BindStatement((GotoStatementSyntax)_nodeToBind, diagnostics);
+                        break;
                     default:
                         _nodeBinder.BindExpression((ExpressionSyntax)_nodeToBind, diagnostics);
                         break;

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

@@ -357,6 +357,62 @@ static void Main(string[] args)
             VerifyOperationTreeAndDiagnosticsForTest<GotoStatementSyntax>(source, expectedOperationTree, expectedDiagnostics);
         }
 
+        [CompilerTrait(CompilerFeature.IOperation)]
+        [Fact, WorkItem(40714, "https://github.com/dotnet/roslyn/issues/40714")]
+        public void InvalidGotoCaseStatement_BadLabel()
+        {
+            string source = @"
+using System;
+
+class Program
+{
+    static void Main(string[] args)
+    {
+        switch (args[0], args[1])
+        {
+            case (string s1, string s2) _:
+                /*<bind>*/goto case args is (var x1, var x2);/*</bind>*/
+                x1 = x2;
+            case (string str, null) _:
+                break;
+        }
+    }
+}
+";
+            string expectedOperationTree = @"
+IInvalidOperation (OperationKind.Invalid, Type: null, IsInvalid) (Syntax: 'goto case a ... 1, var x2);')
+  Children(1):
+      IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: (System.String, System.String), IsInvalid, IsImplicit) (Syntax: 'args is (var x1, var x2)')
+        Conversion: CommonConversion (Exists: False, IsIdentity: False, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+        Operand: 
+          IIsPatternOperation (OperationKind.IsPattern, Type: System.Boolean, IsInvalid) (Syntax: 'args is (var x1, var x2)')
+            Value: 
+              IParameterReferenceOperation: args (OperationKind.ParameterReference, Type: System.String[], IsInvalid) (Syntax: 'args')
+            Pattern: 
+              IRecursivePatternOperation (OperationKind.RecursivePattern, Type: null, IsInvalid) (Syntax: '(var x1, var x2)') (InputType: System.String[], DeclaredSymbol: null, MatchedType: System.String[], DeconstructSymbol: null)
+                DeconstructionSubpatterns (2):
+                    IDeclarationPatternOperation (OperationKind.DeclarationPattern, Type: null, IsInvalid) (Syntax: 'var x1') (InputType: ?, DeclaredSymbol: ?? x1, MatchesNull: True)
+                    IDeclarationPatternOperation (OperationKind.DeclarationPattern, Type: null, IsInvalid) (Syntax: 'var x2') (InputType: ?, DeclaredSymbol: ?? x2, MatchesNull: True)
+                PropertySubpatterns (0)
+";
+            var expectedDiagnostics = new DiagnosticDescription[] {
+                // file.cs(10,18): error CS0163: Control cannot fall through from one case label ('(string s1, string s2) _') to another
+                //             case (string s1, string s2) _:
+                Diagnostic(ErrorCode.ERR_SwitchFallThrough, "(string s1, string s2) _").WithArguments("(string s1, string s2) _").WithLocation(10, 18),
+                // file.cs(11,27): error CS0029: Cannot implicitly convert type 'bool' to '(string, string)'
+                //                 /*<bind>*/goto case args is (var x1, var x2);/*</bind>*/
+                Diagnostic(ErrorCode.ERR_NoImplicitConv, "goto case args is (var x1, var x2);").WithArguments("bool", "(string, string)").WithLocation(11, 27),
+                // file.cs(11,45): error CS1061: 'string[]' does not contain a definition for 'Deconstruct' and no accessible extension method 'Deconstruct' accepting a first argument of type 'string[]' could be found (are you missing a using directive or an assembly reference?)
+                //                 /*<bind>*/goto case args is (var x1, var x2);/*</bind>*/
+                Diagnostic(ErrorCode.ERR_NoSuchMemberOrExtension, "(var x1, var x2)").WithArguments("string[]", "Deconstruct").WithLocation(11, 45),
+                // file.cs(11,45): error CS8129: No suitable 'Deconstruct' instance or extension method was found for type 'string[]', with 2 out parameters and a void return type.
+                //                 /*<bind>*/goto case args is (var x1, var x2);/*</bind>*/
+                Diagnostic(ErrorCode.ERR_MissingDeconstruct, "(var x1, var x2)").WithArguments("string[]", "2").WithLocation(11, 45)
+            };
+
+            VerifyOperationTreeAndDiagnosticsForTest<GotoStatementSyntax>(source, expectedOperationTree, expectedDiagnostics);
+        }
+
         [CompilerTrait(CompilerFeature.IOperation)]
         [Fact, WorkItem(17607, "https://github.com/dotnet/roslyn/issues/17607")]
         public void InvalidGotoCaseStatement_OutsideSwitchStatement()

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

@@ -170,6 +170,20 @@ protected static void VerifyModelForDuplicateVariableDeclarationInSameScope(Sema
             Assert.True(model.LookupNames(declarator.SpanStart).Contains(declarator.Identifier.ValueText));
         }
 
+        internal static void VerifyModelForDuplicateVariableDeclarationInSameScope(
+            SemanticModel model,
+            SingleVariableDesignationSyntax designation,
+            LocalDeclarationKind kind)
+        {
+            var symbol = model.GetDeclaredSymbol(designation);
+            Assert.Equal(designation.Identifier.ValueText, symbol.Name);
+            Assert.Equal(designation, symbol.DeclaringSyntaxReferences.Single().GetSyntax());
+            Assert.Equal(kind, symbol.GetSymbol<LocalSymbol>().DeclarationKind);
+            Assert.Same(symbol, model.GetDeclaredSymbol((SyntaxNode)designation));
+            Assert.NotEqual(symbol, model.LookupSymbols(designation.SpanStart, name: designation.Identifier.ValueText).Single());
+            Assert.True(model.LookupNames(designation.SpanStart).Contains(designation.Identifier.ValueText));
+        }
+
         protected static void VerifyNotAPatternField(SemanticModel model, IdentifierNameSyntax reference)
         {
             var symbol = model.GetSymbolInfo(reference).Symbol;

src/Compilers/CSharp/Test/Semantic/Semantics/PatternMatchingTests3.cs

@@ -1771,5 +1771,122 @@ static void M(int i)
                 Diagnostic(ErrorCode.ERR_AmbigUDConv, "new A()").WithArguments("A.implicit operator B(A)", "B.implicit operator B(A)", "A", "B").WithLocation(16, 43)
                 );
         }
+
+        [WorkItem(40714, "https://github.com/dotnet/roslyn/issues/40714")]
+        [Fact]
+        public void BadGotoCase_01()
+        {
+            var source = @"
+class C
+{
+    static void Example(object a, object b)
+    {
+        switch ((a, b))
+        {
+            case (string str, int[] arr) _:
+                goto case (string str, decimal[] arr);
+            case (string str, decimal[] arr) _:
+                break;
+        }
+    }
+}
+";
+            var compilation = CreateCompilation(source);
+            compilation.VerifyDiagnostics(
+                // (8,18): error CS0163: Control cannot fall through from one case label ('(string str, int[] arr) _') to another
+                //             case (string str, int[] arr) _:
+                Diagnostic(ErrorCode.ERR_SwitchFallThrough, "(string str, int[] arr) _").WithArguments("(string str, int[] arr) _").WithLocation(8, 18),
+                // (8,26): error CS0136: A local or parameter named 'str' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
+                //             case (string str, int[] arr) _:
+                Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "str").WithArguments("str").WithLocation(8, 26),
+                // (8,37): error CS0136: A local or parameter named 'arr' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
+                //             case (string str, int[] arr) _:
+                Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "arr").WithArguments("arr").WithLocation(8, 37),
+                // (9,17): error CS0150: A constant value is expected
+                //                 goto case (string str, decimal[] arr);
+                Diagnostic(ErrorCode.ERR_ConstantExpected, "goto case (string str, decimal[] arr);").WithLocation(9, 17),
+                // (9,28): error CS8185: A declaration is not allowed in this context.
+                //                 goto case (string str, decimal[] arr);
+                Diagnostic(ErrorCode.ERR_DeclarationExpressionNotPermitted, "string str").WithLocation(9, 28),
+                // (9,28): error CS0165: Use of unassigned local variable 'str'
+                //                 goto case (string str, decimal[] arr);
+                Diagnostic(ErrorCode.ERR_UseDefViolation, "string str").WithArguments("str").WithLocation(9, 28),
+                // (9,40): error CS8185: A declaration is not allowed in this context.
+                //                 goto case (string str, decimal[] arr);
+                Diagnostic(ErrorCode.ERR_DeclarationExpressionNotPermitted, "decimal[] arr").WithLocation(9, 40),
+                // (9,40): error CS0165: Use of unassigned local variable 'arr'
+                //                 goto case (string str, decimal[] arr);
+                Diagnostic(ErrorCode.ERR_UseDefViolation, "decimal[] arr").WithArguments("arr").WithLocation(9, 40),
+                // (10,26): error CS0136: A local or parameter named 'str' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
+                //             case (string str, decimal[] arr) _:
+                Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "str").WithArguments("str").WithLocation(10, 26),
+                // (10,41): error CS0136: A local or parameter named 'arr' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter
+                //             case (string str, decimal[] arr) _:
+                Diagnostic(ErrorCode.ERR_LocalIllegallyOverrides, "arr").WithArguments("arr").WithLocation(10, 41)
+                );
+
+            var tree = compilation.SyntaxTrees.Single();
+            var model = compilation.GetSemanticModel(tree);
+
+            var strDecl = tree.GetRoot().DescendantNodes().OfType<SingleVariableDesignationSyntax>().Where(s => s.Identifier.ValueText == "str").ToArray();
+            Assert.Equal(3, strDecl.Length);
+            VerifyModelForDuplicateVariableDeclarationInSameScope(model, strDecl[1], LocalDeclarationKind.DeclarationExpressionVariable);
+
+            var arrDecl = tree.GetRoot().DescendantNodes().OfType<SingleVariableDesignationSyntax>().Where(s => s.Identifier.ValueText == "arr").ToArray();
+            Assert.Equal(3, arrDecl.Length);
+            VerifyModelForDuplicateVariableDeclarationInSameScope(model, arrDecl[1], LocalDeclarationKind.DeclarationExpressionVariable);
+        }
+
+        [WorkItem(40714, "https://github.com/dotnet/roslyn/issues/40714")]
+        [Fact]
+        public void BadGotoCase_02()
+        {
+            var source = @"
+class C
+{
+    static void Example(object a, object b)
+    {
+        switch ((a, b))
+        {
+            case (string str, int[] arr) _:
+                goto case a is (var x1, var x2);
+                x1 = x2;
+            case (string str, decimal[] arr) _:
+                break;
+        }
+    }
+}
+";
+            var compilation = CreateCompilation(source);
+            compilation.VerifyDiagnostics(
+                // (8,18): error CS0163: Control cannot fall through from one case label ('(string str, int[] arr) _') to another
+                //             case (string str, int[] arr) _:
+                Diagnostic(ErrorCode.ERR_SwitchFallThrough, "(string str, int[] arr) _").WithArguments("(string str, int[] arr) _").WithLocation(8, 18),
+                // (9,17): error CS0029: Cannot implicitly convert type 'bool' to '(object a, object b)'
+                //                 goto case a is (var x1, var x2);
+                Diagnostic(ErrorCode.ERR_NoImplicitConv, "goto case a is (var x1, var x2);").WithArguments("bool", "(object a, object b)").WithLocation(9, 17),
+                // (9,32): error CS1061: 'object' does not contain a definition for 'Deconstruct' and no accessible extension method 'Deconstruct' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?)
+                //                 goto case a is (var x1, var x2);
+                Diagnostic(ErrorCode.ERR_NoSuchMemberOrExtension, "(var x1, var x2)").WithArguments("object", "Deconstruct").WithLocation(9, 32),
+                // (9,32): error CS8129: No suitable 'Deconstruct' instance or extension method was found for type 'object', with 2 out parameters and a void return type.
+                //                 goto case a is (var x1, var x2);
+                Diagnostic(ErrorCode.ERR_MissingDeconstruct, "(var x1, var x2)").WithArguments("object", "2").WithLocation(9, 32)
+                );
+
+            var tree = compilation.SyntaxTrees.Single();
+            var model = compilation.GetSemanticModel(tree);
+
+            var x1Decl = GetPatternDeclarations(tree, "x1").ToArray();
+            var x1Ref = GetReferences(tree, "x1").ToArray();
+            Assert.Equal(1, x1Decl.Length);
+            Assert.Equal(1, x1Ref.Length);
+            VerifyModelForDeclarationOrVarSimplePattern(model, x1Decl[0], x1Ref);
+
+            var x2Decl = GetPatternDeclarations(tree, "x2").ToArray();
+            var x2Ref = GetReferences(tree, "x2").ToArray();
+            Assert.Equal(1, x2Decl.Length);
+            Assert.Equal(1, x2Ref.Length);
+            VerifyModelForDeclarationOrVarSimplePattern(model, x2Decl[0], x2Ref);
+        }
     }
 }