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Ensure local function invocations and method references always have null receivers #56395

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9 changes: 8 additions & 1 deletion src/Compilers/CSharp/Portable/Operations/CSharpOperationFactory_Methods.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,14 @@ private IVariableDeclaratorOperation CreateVariableDeclaratorInternal(BoundLocal
}

// Static members cannot have an implicit this receiver
if (symbol != null && symbol.IsStatic && instance.WasCompilerGenerated && instance.Kind == BoundKind.ThisReference)
if (symbol?.IsStatic == true && instance.WasCompilerGenerated && instance.Kind == BoundKind.ThisReference)
{
return null;
}

// Local functions are not invoked on receivers from a language point of view, and thus we do not expose
// a receiver for them.
if (symbol is MethodSymbol { MethodKind: MethodKind.LocalFunction })
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@AlekseyTs AlekseyTs Sep 16, 2021 •
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if (symbol is MethodSymbol { MethodKind: MethodKind.LocalFunction })

Would it be better to adjust binding so that it wouldn't add a receiver? #Closed

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I guess we are doing this for regular static methods too

{
return null;
}
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77 changes: 77 additions & 0 deletions src/Compilers/CSharp/Test/IOperation/IOperation/IOperationTests_IInvocationOperation.cs
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Expand Up @@ -6,6 +6,7 @@

using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Test.Utilities;
using Roslyn.Test.Utilities;
using Xunit;

namespace Microsoft.CodeAnalysis.CSharp.UnitTests
Expand Down Expand Up @@ -1312,5 +1313,81 @@ static void M1(object o1, object o2, object o3) { }
";
VerifyFlowGraphAndDiagnosticsForTest<BlockSyntax>(source, expectedFlowGraph, expectedDiagnostics);
}

[Theory, WorkItem(51715, "https://github.com/dotnet/roslyn/issues/51715")]
[InlineData("static")]
[InlineData("")]
public void Invocation_LocalFunction_01(string modifier)
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Invocation_LocalFunction_01

It looks like all the tests are testing scenarios within an implicit static method. Consider testing inside a regular instance method and, perhaps, a regular static method as well.

{
var code = @"
using System;

/*<bind>*/localFunction()/*</bind>*/;

" + modifier + @" void localFunction() {}
";

var expectedDiagnostics = DiagnosticDescription.None;
var expectedTree = @"
IInvocationOperation (void localFunction()) (OperationKind.Invocation, Type: System.Void) (Syntax: 'localFunction()')
Instance Receiver:
null
Arguments(0)
";

VerifyOperationTreeAndDiagnosticsForTest<InvocationExpressionSyntax>(code, expectedTree, expectedDiagnostics);
}

[Fact, WorkItem(51715, "https://github.com/dotnet/roslyn/issues/51715")]
public void Invocation_LocalFunction_02()
{
var code = @"
using System;

int localVariable = 1;
/*<bind>*/localFunction()/*</bind>*/;

int localFunction() => localVariable;
";

var expectedDiagnostics = DiagnosticDescription.None;
var expectedTree = @"
IInvocationOperation (System.Int32 localFunction()) (OperationKind.Invocation, Type: System.Int32) (Syntax: 'localFunction()')
Instance Receiver:
null
Arguments(0)
";

VerifyOperationTreeAndDiagnosticsForTest<InvocationExpressionSyntax>(code, expectedTree, expectedDiagnostics);
}

[Fact, WorkItem(51715, "https://github.com/dotnet/roslyn/issues/51715")]
public void Invocation_LocalFunction_03()
{
var code = @"
using System;

int localVariable = 1;
/*<bind>*/localFunction()/*</bind>*/;

static int localFunction() => localVariable;
";

var expectedDiagnostics = new DiagnosticDescription[]
{
// (7,31): error CS8421: A static local function cannot contain a reference to 'localVariable'.
// static int localFunction() => localVariable;
Diagnostic(ErrorCode.ERR_StaticLocalFunctionCannotCaptureVariable, "localVariable").WithArguments("localVariable").WithLocation(7, 31)
};

var expectedTree = @"
IInvocationOperation (System.Int32 localFunction()) (OperationKind.Invocation, Type: System.Int32) (Syntax: 'localFunction()')
Instance Receiver:
null
Arguments(0)
";

VerifyOperationTreeAndDiagnosticsForTest<InvocationExpressionSyntax>(code, expectedTree, expectedDiagnostics);
}
}
}
84 changes: 84 additions & 0 deletions src/Compilers/CSharp/Test/IOperation/IOperation/IOperationTests_IMethodReferenceOperation.cs
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Expand Up @@ -305,5 +305,89 @@ void M(C c1, C c2, System.Func<int> m1, System.Func<int> m2)

VerifyFlowGraphAndDiagnosticsForTest<BlockSyntax>(source, expectedFlowGraph, expectedDiagnostics);
}

[Fact, WorkItem(51715, "https://github.com/dotnet/roslyn/issues/51715")]
public void MethodReference_LocalFunction_01()
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Same comment as for the invocation tests.

{
var code = @"
using System;
Action a = /*<bind>*/localFunction/*</bind>*/;

void localFunction() {}
";

var expectedDiagnostics = DiagnosticDescription.None;
var expectedTree = @"
IMethodReferenceOperation: void localFunction() (OperationKind.MethodReference, Type: null) (Syntax: 'localFunction')
Instance Receiver:
null";

VerifyOperationTreeAndDiagnosticsForTest<IdentifierNameSyntax>(code, expectedTree, expectedDiagnostics);
}

[Fact, WorkItem(51715, "https://github.com/dotnet/roslyn/issues/51715")]
public void MethodReference_LocalFunction_02()
{
var code = @"
using System;
Action a = /*<bind>*/localFunction/*</bind>*/;

static void localFunction() {}
";

var expectedDiagnostics = DiagnosticDescription.None;
var expectedTree = @"
IMethodReferenceOperation: void localFunction() (Static) (OperationKind.MethodReference, Type: null) (Syntax: 'localFunction')
Instance Receiver:
null";

VerifyOperationTreeAndDiagnosticsForTest<IdentifierNameSyntax>(code, expectedTree, expectedDiagnostics);
}

[Fact, WorkItem(51715, "https://github.com/dotnet/roslyn/issues/51715")]
public void MethodReference_LocalFunction_03()
{
var code = @"
using System;
int local = 1;
Func<int> a = /*<bind>*/localFunction/*</bind>*/;

int localFunction() => local;
";

var expectedDiagnostics = DiagnosticDescription.None;
var expectedTree = @"
IMethodReferenceOperation: System.Int32 localFunction() (OperationKind.MethodReference, Type: null) (Syntax: 'localFunction')
Instance Receiver:
null";

VerifyOperationTreeAndDiagnosticsForTest<IdentifierNameSyntax>(code, expectedTree, expectedDiagnostics);
}

[Fact, WorkItem(51715, "https://github.com/dotnet/roslyn/issues/51715")]
public void MethodReference_LocalFunction_04()
{
var code = @"
using System;
int local = 1;
Func<int> a = /*<bind>*/localFunction/*</bind>*/;

static int localFunction() => local;
";

var expectedDiagnostics = new DiagnosticDescription[]
{
// (6,31): error CS8421: A static local function cannot contain a reference to 'local'.
// static int localFunction() => local;
Diagnostic(ErrorCode.ERR_StaticLocalFunctionCannotCaptureVariable, "local").WithArguments("local").WithLocation(6, 31)
};

var expectedTree = @"
IMethodReferenceOperation: System.Int32 localFunction() (Static) (OperationKind.MethodReference, Type: null) (Syntax: 'localFunction')
Instance Receiver:
null";

VerifyOperationTreeAndDiagnosticsForTest<IdentifierNameSyntax>(code, expectedTree, expectedDiagnostics);
}
}
}