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Merged
merged 3 commits into from
Oct 16, 2025
Merged

Project byte* parameters as Span<byte> #1488

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8dd14ba
Project byte* parameters as Span<byte>
jevansaks Oct 16, 2025
644cf76
Add an extern method test
jevansaks Oct 16, 2025
b824207
Remove blank line
jevansaks Oct 16, 2025
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22 changes: 19 additions & 3 deletions src/Microsoft.Windows.CsWin32/Generator.FriendlyOverloads.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -127,13 +127,18 @@ private IEnumerable<MethodDeclarationSyntax> DeclareFriendlyOverloads(MethodDefi
countParamIndex = nativeArrayInfo.CountParamIndex;
countConst = nativeArrayInfo.CountConst;
}
else if (externParam.Type is PointerTypeSyntax { ElementType: PredefinedTypeSyntax { Keyword.RawKind: (int)SyntaxKind.ByteKeyword } } && this.FindInteropDecorativeAttribute(paramAttributes, MemorySizeAttribute) is CustomAttribute memorySizeAttribute)
else if (externParam.Type is PointerTypeSyntax { ElementType: PredefinedTypeSyntax { Keyword.RawKind: (int)SyntaxKind.ByteKeyword } })
{
// A very special case as documented in https://github.com/microsoft/win32metadata/issues/1555
// where MemorySizeAttribute is applied to byte* parameters to indicate the size of the buffer.
// Also https://github.com/microsoft/CsWin32/issues/1487 showed that byte* parameters are very unlikely to be a
// single byte so it's safer to assume it's an un-annotated array.
isArray = true;
MemorySize memorySize = DecodeMemorySizeAttribute(memorySizeAttribute);
countParamIndex = memorySize.BytesParamIndex;
if (this.FindInteropDecorativeAttribute(paramAttributes, MemorySizeAttribute) is CustomAttribute memorySizeAttribute)
{
MemorySize memorySize = DecodeMemorySizeAttribute(memorySizeAttribute);
countParamIndex = memorySize.BytesParamIndex;
}
}

if (mustRemainAsPointer)
Expand Down Expand Up @@ -301,6 +306,17 @@ private IEnumerable<MethodDeclarationSyntax> DeclareFriendlyOverloads(MethodDefi
LiteralExpression(SyntaxKind.NumericLiteralExpression, Literal(countConst.Value))),
ThrowStatement(ObjectCreationExpression(IdentifierName(nameof(ArgumentException))).WithArgumentList(ArgumentList()))));
}
else if (!isPointerToPointer && this.canUseSpan && externParam.Type is PointerTypeSyntax)
{
signatureChanged = true;

// Handle the byte* => Span<byte> mapping
parameters[param.SequenceNumber - 1] = parameters[param.SequenceNumber - 1]
.WithType((isConst ? MakeReadOnlySpanOfT(elementType) : MakeSpanOfT(elementType)).WithTrailingTrivia(TriviaList(Space)));
fixedBlocks.Add(VariableDeclaration(externParam.Type).AddVariables(
VariableDeclarator(localName.Identifier).WithInitializer(EqualsValueClause(origName))));
arguments[param.SequenceNumber - 1] = Argument(localName);
}
else if (isNullTerminated && isConst && parameters[param.SequenceNumber - 1].Type is PointerTypeSyntax { ElementType: PredefinedTypeSyntax { Keyword: { RawKind: (int)SyntaxKind.CharKeyword } } })
{
// replace char* with string
Expand Down
1 change: 1 addition & 0 deletions test/CsWin32Generator.Tests/CsWin32GeneratorTests.cs
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Expand Up @@ -87,6 +87,7 @@ public async Task TestGenerateSomethingInWin32System()

[Theory]
[InlineData("IMFMediaKeySession", "get_KeySystem", "winmdroot.Foundation.BSTR* keySystem")]
[InlineData("AddPrinterW", "AddPrinter", "winmdroot.Foundation.PWSTR pName, uint Level, Span<byte> pPrinter")]
public async Task VerifySignature(string api, string member, string signature)
{
// If we need CharSet _and_ we generate something in Windows.Win32.System, the partially qualified reference breaks.
Expand Down
10 changes: 10 additions & 0 deletions test/Microsoft.Windows.CsWin32.Tests/ExternMethodTests.cs
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Expand Up @@ -121,6 +121,16 @@ static void Use()
this.AssertNoDiagnostics(this.compilation, logAllGeneratedCode: false, acceptable: isAcceptable);
}

[Fact]
public void PrinterApiProjectsBytePointerParameter()
{
this.compilation = this.starterCompilations["net35"];
this.GenerateApi("AddPrinter");
var methodSignatures = this.FindGeneratedMethod("AddPrinter_SafeHandle").Select(x => x.ParameterList.ToString());
Assert.Contains("(winmdroot.Foundation.PWSTR pName, uint Level, byte* pPrinter)", methodSignatures);
}


private static AttributeSyntax? FindDllImportAttribute(SyntaxList<AttributeListSyntax> attributeLists) => attributeLists.SelectMany(al => al.Attributes).FirstOrDefault(a => a.Name.ToString() == "DllImport");

private IEnumerable<MethodDeclarationSyntax> GenerateMethod(string methodName)
Expand Down
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