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Merged
jcouv merged 2 commits into from
Nov 19, 2025
Merged

Extensions: fix issue with paramref #81269

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73d29fe
Extensions: fix issue with paramref
Nov 15, 2025
c102ae8
Add tests
Nov 18, 2025
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15 changes: 12 additions & 3 deletions src/Compilers/CSharp/Portable/Binder/BinderFactory.BinderFactoryVisitor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1175,9 +1175,11 @@ public override Binder VisitXmlNameAttribute(XmlNameAttributeSyntax parent)
switch (elementKind)
{
case XmlNameAttributeElementKind.Parameter:
case XmlNameAttributeElementKind.ParameterReference:
extraInfo = NodeUsage.DocumentationCommentParameter;
break;
case XmlNameAttributeElementKind.ParameterReference:
extraInfo = NodeUsage.DocumentationCommentParameterReference;
break;
case XmlNameAttributeElementKind.TypeParameter:
extraInfo = NodeUsage.DocumentationCommentTypeParameter;
break;
Expand Down Expand Up @@ -1236,7 +1238,7 @@ public override Binder VisitXmlNameAttribute(XmlNameAttributeSyntax parent)
/// </summary>
private Binder GetParameterNameAttributeValueBinder(MemberDeclarationSyntax memberSyntax, bool isParamRef, Binder nextBinder)
{
if (memberSyntax is BaseMethodDeclarationSyntax { ParameterList: { ParameterCount: > 0 } } baseMethodDeclSyntax)
if (memberSyntax is BaseMethodDeclarationSyntax baseMethodDeclSyntax)
{
Binder outerBinder = VisitCore(memberSyntax.Parent);
MethodSymbol method = GetMethodSymbol(baseMethodDeclSyntax, outerBinder);
Expand All @@ -1246,7 +1248,14 @@ private Binder GetParameterNameAttributeValueBinder(MemberDeclarationSyntax memb
nextBinder = new WithExtensionParameterBinder(method.ContainingType, nextBinder);
}

return new WithParametersBinder(method.Parameters, nextBinder);
if (method.ParameterCount > 0)
{
return new WithParametersBinder(method.Parameters, nextBinder);
}
else
{
return nextBinder;
}
}
else if (memberSyntax is ExtensionBlockDeclarationSyntax extensionDeclaration)
{
Expand Down
5 changes: 3 additions & 2 deletions src/Compilers/CSharp/Portable/Binder/BinderFactory.NodeUsage.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,8 +27,9 @@ internal enum NodeUsage : byte
CompilationUnitScriptUsings = 1 << 2,

DocumentationCommentParameter = 1 << 0,
DocumentationCommentTypeParameter = 1 << 1,
DocumentationCommentTypeParameterReference = 1 << 2,
DocumentationCommentParameterReference = 1 << 1,
DocumentationCommentTypeParameter = 1 << 2,
DocumentationCommentTypeParameterReference = 1 << 3,

CrefParameterOrReturnType = 1 << 0,
}
Expand Down
157 changes: 156 additions & 1 deletion src/Compilers/CSharp/Test/Emit3/Semantics/ExtensionTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -51327,6 +51327,10 @@ static class E
// (9,30): warning CS1573: Parameter 'o2' has no matching param tag in the XML comment for 'E.extension(object).M(object)' (but other parameters do)
// public void M(object o2) => throw null!;
Diagnostic(ErrorCode.WRN_MissingParamTag, "o2").WithArguments("o2", "E.extension(object).M(object)").WithLocation(9, 30));

var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
AssertEx.SequenceEqual(["(o, null)"], PrintXmlNameSymbols(tree, model));
}

[Fact]
Expand All @@ -51347,6 +51351,10 @@ static class E
""";
var comp = CreateCompilation(src, parseOptions: TestOptions.RegularPreviewWithDocumentationComments);
comp.VerifyEmitDiagnostics();

var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
AssertEx.SequenceEqual(["(o, System.Object o)"], PrintXmlNameSymbols(tree, model));
}

[Fact]
Expand Down Expand Up @@ -51465,7 +51473,7 @@ static class E
/// <summary>Summary for extension block</summary>
extension<T>(T t)
{
/// <summary>Summary for M</summary>
/// <summary>Summary for M <typeparamref name="T"/> </summary>
/// <typeparam name="T">Description for T</typeparam>
public static void M<U>(U u) => throw null!;
}
Expand Down Expand Up @@ -51691,6 +51699,86 @@ public static int P4 { set { } }
Diagnostic(ErrorCode.WRN_UnmatchedParamRefTag, "value").WithArguments("value", "E.extension(object).P2").WithLocation(8, 53));
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/81217")]
public void XmlDoc_ParamRef_04()
{
// No parameter on method
var src = """
static class E
{
extension(object o)
{
/// <returns><paramref name="o"/></returns>
public object M() => o;
}
}
""";
var comp = CreateCompilation(src, parseOptions: TestOptions.RegularPreviewWithDocumentationComments,
assemblyName: "paramref_04");
comp.VerifyEmitDiagnostics();

var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
AssertEx.SequenceEqual(["(o, System.Object o)"], PrintXmlNameSymbols(tree, model));
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/81217")]
public void XmlDoc_ParamRef_05()
{
// One parameter on method
var src = """
static class E
{
extension(object o)
{
/// <summary><paramref name="o"/></summary>
public object M(int i) => o;
}
}
""";
var comp = CreateCompilation(src, parseOptions: TestOptions.RegularPreviewWithDocumentationComments,
assemblyName: "paramref_05");
comp.VerifyEmitDiagnostics();

var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
AssertEx.SequenceEqual(["(o, System.Object o)"], PrintXmlNameSymbols(tree, model));
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/81217")]
public void XmlDoc_ParamRef_06()
{
// <params> preceeds <paramref>
var src = """
using System;

static class E
{
/// <param name="value">Param value</param>
extension(ReadOnlySpan<char> value)
{
/// <param name="n">Param n</param>
/// <param name="delimiter">Param delimiter</param>
/// <returns><paramref name="value"/></returns>
public ReadOnlySpan<char> GetNthDelimitedItem(int n, ReadOnlySpan<char> delimiter) => throw null !;
}
}
""";
var comp = CreateCompilation(src, parseOptions: TestOptions.RegularPreviewWithDocumentationComments,
assemblyName: "paramref_06", targetFramework: TargetFramework.Net100);

comp.VerifyEmitDiagnostics();

var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
AssertEx.SequenceEqual([
"(value, System.ReadOnlySpan<System.Char> value)",
"(n, System.Int32 n)",
"(delimiter, System.ReadOnlySpan<System.Char> delimiter)",
"(value, System.ReadOnlySpan<System.Char> value)"],
PrintXmlNameSymbols(tree, model));
}

[Fact]
public void XmlDoc_TypeParamRef_01()
{
Expand Down Expand Up @@ -51747,6 +51835,73 @@ static class E
AssertEx.SequenceEqual(["(T, null)", "(T, T)"], PrintXmlNameSymbols(tree, model));
}

[Fact]
public void XmlDoc_TypeParamRef_03()
{
var src = """
static class E
{
/// <typeparam name="T1"/>
extension<T1>(int)
{
/// <summary><typeparamref name="T1"/></summary>
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@AlekseyTs AlekseyTs Nov 18, 2025 •
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///

Do we have a similar test with a non generic method? With a property? #Closed

/// <typeparam name="T2"/>
public static void M<T2>() => throw null!;
}
}
""";
var comp = CreateCompilation(src, parseOptions: TestOptions.RegularPreviewWithDocumentationComments);
comp.VerifyEmitDiagnostics();

var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
AssertEx.SequenceEqual(["(T1, T1)", "(T1, T1)", "(T2, T2)"], PrintXmlNameSymbols(tree, model));
}

[Fact]
public void XmlDoc_TypeParamRef_04()
{
var src = """
static class E
{
/// <typeparam name="T1"/>
extension<T1>(int)
{
/// <summary><typeparamref name="T1"/></summary>
public static void M() => throw null!;
}
}
""";
var comp = CreateCompilation(src, parseOptions: TestOptions.RegularPreviewWithDocumentationComments);
comp.VerifyEmitDiagnostics();

var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
AssertEx.SequenceEqual(["(T1, T1)", "(T1, T1)"], PrintXmlNameSymbols(tree, model));
}

[Fact]
public void XmlDoc_TypeParamRef_05()
{
var src = """
static class E
{
/// <typeparam name="T1"/>
extension<T1>(T1)
{
/// <summary><typeparamref name="T1"/></summary>
public static int Property => throw null!;
}
}
""";
var comp = CreateCompilation(src, parseOptions: TestOptions.RegularPreviewWithDocumentationComments);
comp.VerifyEmitDiagnostics();

var tree = comp.SyntaxTrees.Single();
var model = comp.GetSemanticModel(tree);
AssertEx.SequenceEqual(["(T1, T1)", "(T1, T1)"], PrintXmlNameSymbols(tree, model));
}

[Fact]
public void AnalyzerActions_01()
{
Expand Down
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