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Fix parsing of scoped before this in parameter list #80718

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Fix parsing of scoped before this in parameter list #80718

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72ee12b
Initial plan
Copilot Oct 14, 2025
af22ea1
Fix parsing of scoped before this in parameter list
Copilot Oct 14, 2025
6ddd47c
Address PR feedback: remove extra lines and add attribute tests
Copilot Oct 14, 2025
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4 changes: 2 additions & 2 deletions src/Compilers/CSharp/Portable/Parser/LanguageParser.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4880,8 +4880,8 @@ private void ParseParameterModifiers(SyntaxListBuilder modifiers, bool isFunctio
{
modifiers.Add(scopedKeyword);

// Look if ref/out/in/readonly are next
while (this.CurrentToken.Kind is SyntaxKind.RefKeyword or SyntaxKind.OutKeyword or SyntaxKind.InKeyword or SyntaxKind.ReadOnlyKeyword)
// Look if ref/out/in/readonly/this are next
while (this.CurrentToken.Kind is SyntaxKind.RefKeyword or SyntaxKind.OutKeyword or SyntaxKind.InKeyword or SyntaxKind.ReadOnlyKeyword or SyntaxKind.ThisKeyword)
{
modifiers.Add(this.EatToken());
}
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60 changes: 60 additions & 0 deletions src/Compilers/CSharp/Test/Emit3/Attributes/AttributeTests_LifetimeAnnotation.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -560,6 +560,66 @@ [ScopedRef] scoped R r
});
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/78491")]
public void EmitAttribute_ExtensionMethodParameters_ScopedInThis()
{
var source =
@"static class Extensions
{
public static void F(scoped in this int i) { }
}";
var comp = CreateCompilation(source);
var expected =
@"void Extensions.F(this scoped in System.Int32 i)
[ScopedRef] scoped in System.Int32 i
";
CompileAndVerify(comp, symbolValidator: module =>
{
Assert.Equal("System.Runtime.CompilerServices.ScopedRefAttribute", GetScopedRefType(module).ToTestDisplayString());
AssertScopedRefAttributes(module, expected);
});
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/78491")]
public void EmitAttribute_ExtensionMethodParameters_ScopedRefThis()
{
var source =
@"static class Extensions
{
public static void F(scoped ref this int i) { }
}";
var comp = CreateCompilation(source);
var expected =
@"void Extensions.F(this scoped ref System.Int32 i)
[ScopedRef] scoped ref System.Int32 i
";
CompileAndVerify(comp, symbolValidator: module =>
{
Assert.Equal("System.Runtime.CompilerServices.ScopedRefAttribute", GetScopedRefType(module).ToTestDisplayString());
AssertScopedRefAttributes(module, expected);
});
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/78491")]
public void EmitAttribute_ExtensionMethodParameters_ScopedRefReadonlyThis()
{
var source =
@"static class Extensions
{
public static void F(scoped ref readonly this int i) { }
}";
var comp = CreateCompilation(source);
var expected =
@"void Extensions.F(this scoped ref readonly System.Int32 i)
[ScopedRef] scoped ref readonly System.Int32 i
";
CompileAndVerify(comp, symbolValidator: module =>
{
Assert.Equal("System.Runtime.CompilerServices.ScopedRefAttribute", GetScopedRefType(module).ToTestDisplayString());
AssertScopedRefAttributes(module, expected);
});
}

private static void AssertScopedRefAttributes(ModuleSymbol module, string expected)
{
var actual = ScopedRefAttributesVisitor.GetString((PEModuleSymbol)module);
Expand Down
139 changes: 139 additions & 0 deletions src/Compilers/CSharp/Test/Syntax/Parsing/DeclarationScopeParsingTests.cs
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Expand Up @@ -14944,5 +14944,144 @@ public void Catch_03()
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/78491")]
public void ScopedWithThis_01()
{
var source = "void M(scoped in this int p);";
UsingDeclaration(source);

N(SyntaxKind.MethodDeclaration);
{
N(SyntaxKind.PredefinedType);
{
N(SyntaxKind.VoidKeyword);
}
N(SyntaxKind.IdentifierToken, "M");
N(SyntaxKind.ParameterList);
{
N(SyntaxKind.OpenParenToken);
N(SyntaxKind.Parameter);
{
N(SyntaxKind.ScopedKeyword);
N(SyntaxKind.InKeyword);
N(SyntaxKind.ThisKeyword);
N(SyntaxKind.PredefinedType);
{
N(SyntaxKind.IntKeyword);
}
N(SyntaxKind.IdentifierToken, "p");
}
N(SyntaxKind.CloseParenToken);
}
N(SyntaxKind.SemicolonToken);
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/78491")]
public void ScopedWithThis_02()
{
var source = "void M(scoped ref this int p);";
UsingDeclaration(source);

N(SyntaxKind.MethodDeclaration);
{
N(SyntaxKind.PredefinedType);
{
N(SyntaxKind.VoidKeyword);
}
N(SyntaxKind.IdentifierToken, "M");
N(SyntaxKind.ParameterList);
{
N(SyntaxKind.OpenParenToken);
N(SyntaxKind.Parameter);
{
N(SyntaxKind.ScopedKeyword);
N(SyntaxKind.RefKeyword);
N(SyntaxKind.ThisKeyword);
N(SyntaxKind.PredefinedType);
{
N(SyntaxKind.IntKeyword);
}
N(SyntaxKind.IdentifierToken, "p");
}
N(SyntaxKind.CloseParenToken);
}
N(SyntaxKind.SemicolonToken);
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/78491")]
public void ScopedWithThis_03()
{
// Test scoped ref readonly this
var source = "void M(scoped ref readonly this int p);";
UsingDeclaration(source);

N(SyntaxKind.MethodDeclaration);
{
N(SyntaxKind.PredefinedType);
{
N(SyntaxKind.VoidKeyword);
}
N(SyntaxKind.IdentifierToken, "M");
N(SyntaxKind.ParameterList);
{
N(SyntaxKind.OpenParenToken);
N(SyntaxKind.Parameter);
{
N(SyntaxKind.ScopedKeyword);
N(SyntaxKind.RefKeyword);
N(SyntaxKind.ReadOnlyKeyword);
N(SyntaxKind.ThisKeyword);
N(SyntaxKind.PredefinedType);
{
N(SyntaxKind.IntKeyword);
}
N(SyntaxKind.IdentifierToken, "p");
}
N(SyntaxKind.CloseParenToken);
}
N(SyntaxKind.SemicolonToken);
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/78491")]
public void ScopedWithThis_04()
{
// Test that this scoped in still works
var source = "void M(this scoped in int p);";
UsingDeclaration(source);

N(SyntaxKind.MethodDeclaration);
{
N(SyntaxKind.PredefinedType);
{
N(SyntaxKind.VoidKeyword);
}
N(SyntaxKind.IdentifierToken, "M");
N(SyntaxKind.ParameterList);
{
N(SyntaxKind.OpenParenToken);
N(SyntaxKind.Parameter);
{
N(SyntaxKind.ThisKeyword);
N(SyntaxKind.ScopedKeyword);
N(SyntaxKind.InKeyword);
N(SyntaxKind.PredefinedType);
{
N(SyntaxKind.IntKeyword);
}
N(SyntaxKind.IdentifierToken, "p");
}
N(SyntaxKind.CloseParenToken);
}
N(SyntaxKind.SemicolonToken);
}
EOF();
}
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@copilot Remove extra empty lines below. And for the scenarios you've added above, add corresponding tests to AttributeTests_ScopedRef for the scenarios that aren't already covered.

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Done. Removed the extra empty lines and added three attribute tests for the extension method scenarios with this keyword combinations in commit af5f4ec.

}
}