Skip to content

Fix zero-length bitfield handling in the P/Invoke generator #817

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
tannergooding merged 2 commits into from
Jul 17, 2026
Merged

Fix zero-length bitfield handling in the P/Invoke generator #817

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
fc58df5
Fix zero-length bitfield handling in the P/Invoke generator
tannergooding Jul 17, 2026
7f924f2
Merge commit '5ea8318b1203f0fe61da104b91390201e23239f8' into tannergo…
tannergooding Jul 17, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 9 additions & 1 deletion sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.VisitRecordDecl.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -533,7 +533,15 @@ private void VisitRecordDecl(RecordDecl recordDecl)
{
if (fieldDecl.IsBitField)
{
VisitBitfieldDecl(fieldDecl, bitfieldDescs, recordDecl, contextName: "", ref bitfieldIndex, ref bitfieldPreviousSize, ref bitfieldRemainingBits);
if (fieldDecl.IsZeroLengthBitField)
{
bitfieldPreviousSize = 0;
bitfieldRemainingBits = 0;
}
else
{
VisitBitfieldDecl(fieldDecl, bitfieldDescs, recordDecl, contextName: "", ref bitfieldIndex, ref bitfieldPreviousSize, ref bitfieldRemainingBits);
}
}
else
{
Expand Down
9 changes: 9 additions & 0 deletions sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1408,6 +1408,15 @@ private BitfieldDesc[] GetBitfieldDescs(RecordDecl recordDecl)
continue;
}

if (fieldDecl.IsZeroLengthBitField)
{
// A zero-length bitfield (`int : 0;`) names no storage and only forces the next
// bitfield into a fresh storage unit, so it emits no region and resets the run.
previousSize = 0;
remainingBits = 0;
continue;
}

var type = fieldDecl.Type;
var currentSize = type.Handle.SizeOf;

Expand Down
39 changes: 39 additions & 0 deletions ...nitTests/Baseline/Baselines/StructDeclaration/ZeroLengthBitfieldTest.CSharp.Compatible.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
namespace ClangSharp.Test
{
public partial struct MyStruct
{
[NativeBitfield("o0_b0_1", offset: 0, length: 1)]
public uint _bitfield1;

[NativeTypeName("unsigned int : 1")]
public uint o0_b0_1
{
get
{
return _bitfield1 & 0x1u;
}

set
{
_bitfield1 = (_bitfield1 & ~0x1u) | (value & 0x1u);
}
}

[NativeBitfield("o4_b0_1", offset: 0, length: 1)]
public uint _bitfield2;

[NativeTypeName("unsigned int : 1")]
public uint o4_b0_1
{
get
{
return _bitfield2 & 0x1u;
}

set
{
_bitfield2 = (_bitfield2 & ~0x1u) | (value & 0x1u);
}
}
}
}
39 changes: 39 additions & 0 deletions ...r.UnitTests/Baseline/Baselines/StructDeclaration/ZeroLengthBitfieldTest.CSharp.Default.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
namespace ClangSharp.Test
{
public partial struct MyStruct
{
[NativeBitfield("o0_b0_1", offset: 0, length: 1)]
public uint _bitfield1;

[NativeTypeName("unsigned int : 1")]
public uint o0_b0_1
{
readonly get
{
return _bitfield1 & 0x1u;
}

set
{
_bitfield1 = (_bitfield1 & ~0x1u) | (value & 0x1u);
}
}

[NativeBitfield("o4_b0_1", offset: 0, length: 1)]
public uint _bitfield2;

[NativeTypeName("unsigned int : 1")]
public uint o4_b0_1
{
readonly get
{
return _bitfield2 & 0x1u;
}

set
{
_bitfield2 = (_bitfield2 & ~0x1u) | (value & 0x1u);
}
}
}
}
39 changes: 39 additions & 0 deletions ...or.UnitTests/Baseline/Baselines/StructDeclaration/ZeroLengthBitfieldTest.CSharp.Latest.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
namespace ClangSharp.Test
{
public partial struct MyStruct
{
[NativeBitfield("o0_b0_1", offset: 0, length: 1)]
public uint _bitfield1;

[NativeTypeName("unsigned int : 1")]
public uint o0_b0_1
{
readonly get
{
return _bitfield1 & 0x1u;
}

set
{
_bitfield1 = (_bitfield1 & ~0x1u) | (value & 0x1u);
}
}

[NativeBitfield("o4_b0_1", offset: 0, length: 1)]
public uint _bitfield2;

[NativeTypeName("unsigned int : 1")]
public uint o4_b0_1
{
readonly get
{
return _bitfield2 & 0x1u;
}

set
{
_bitfield2 = (_bitfield2 & ~0x1u) | (value & 0x1u);
}
}
}
}
39 changes: 39 additions & 0 deletions ...r.UnitTests/Baseline/Baselines/StructDeclaration/ZeroLengthBitfieldTest.CSharp.Preview.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
namespace ClangSharp.Test
{
public partial struct MyStruct
{
[NativeBitfield("o0_b0_1", offset: 0, length: 1)]
public uint _bitfield1;

[NativeTypeName("unsigned int : 1")]
public uint o0_b0_1
{
readonly get
{
return _bitfield1 & 0x1u;
}

set
{
_bitfield1 = (_bitfield1 & ~0x1u) | (value & 0x1u);
}
}

[NativeBitfield("o4_b0_1", offset: 0, length: 1)]
public uint _bitfield2;

[NativeTypeName("unsigned int : 1")]
public uint o4_b0_1
{
readonly get
{
return _bitfield2 & 0x1u;
}

set
{
_bitfield2 = (_bitfield2 & ~0x1u) | (value & 0x1u);
}
}
}
}
35 changes: 35 additions & 0 deletions ...keGenerator.UnitTests/Baseline/Baselines/StructDeclaration/ZeroLengthBitfieldTest.Xml.xml
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,35 @@
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<bindings>
<namespace name="ClangSharp.Test">
<struct name="MyStruct" access="public">
<field name="_bitfield1" access="public">
<attribute>NativeBitfield("o0_b0_1", offset: 0, length: 1)</attribute>
<type>uint</type>
</field>
<field name="o0_b0_1" access="public">
<type native="unsigned int : 1">uint</type>
<get>
<code>return <bitfieldName>_bitfield1</bitfieldName> &amp; 0x<bitwidthHexStringBacking>1u</bitwidthHexStringBacking>;</code>
</get>
<set>
<code>
<bitfieldName>_bitfield1</bitfieldName> = (_bitfield1 &amp; ~0x<bitwidthHexStringBacking>1u</bitwidthHexStringBacking>) | (value &amp; 0x<bitwidthHexString>1u</bitwidthHexString>);</code>
</set>
</field>
<field name="_bitfield2" access="public">
<attribute>NativeBitfield("o4_b0_1", offset: 0, length: 1)</attribute>
<type>uint</type>
</field>
<field name="o4_b0_1" access="public">
<type native="unsigned int : 1">uint</type>
<get>
<code>return <bitfieldName>_bitfield2</bitfieldName> &amp; 0x<bitwidthHexStringBacking>1u</bitwidthHexStringBacking>;</code>
</get>
<set>
<code>
<bitfieldName>_bitfield2</bitfieldName> = (_bitfield2 &amp; ~0x<bitwidthHexStringBacking>1u</bitwidthHexStringBacking>) | (value &amp; 0x<bitwidthHexString>1u</bitwidthHexString>);</code>
</set>
</field>
</struct>
</namespace>
</bindings>
14 changes: 14 additions & 0 deletions tests/ClangSharp.PInvokeGenerator.UnitTests/Baseline/StructDeclarationTest.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -152,6 +152,20 @@ struct MyStruct3
return ValidateAsync(nameof(BitfieldWithNativeBitfieldAttributeTest), inputContents, additionalConfigOptions: PInvokeGeneratorConfigurationOptions.GenerateNativeBitfieldAttribute);
}

[Test]
public Task ZeroLengthBitfieldTest()
{
var inputContents = @"struct MyStruct
{
unsigned int o0_b0_1 : 1;
unsigned int : 0;
unsigned int o4_b0_1 : 1;
};
";

return ValidateAsync(nameof(ZeroLengthBitfieldTest), inputContents, additionalConfigOptions: PInvokeGeneratorConfigurationOptions.GenerateNativeBitfieldAttribute);
}

[Test]
public Task DeclTypeTest()
{
Expand Down
Loading