Bug with new C# 11 nint/nuint handling for IntPtr/UIntPtr

[ElektroKill]

Input code

System.IntPtr from .NET 7 System.Private.CoreLib

Erroneous output

An assertion is hit regarding using declarations:

ICSharpCode.ILSpy.AssertionFailedException: Should not insert using declaration for namespace that is missing from the superset: System.Runtime.Versioning
   at ICSharpCode.ILSpy.ILSpyTraceListener.Fail(String message, String detailMessage) in E:\Programming\RiderProjects\ILSpy\ILSpy\ILSpyTraceListener.cs:line 86
   at System.Diagnostics.TraceInternal.Fail(String message, String detailMessage)
   at System.Diagnostics.TraceInternal.TraceProvider.Fail(String message, String detailMessage)
   at System.Diagnostics.Debug.Fail(String message, String detailMessage)
   at System.Diagnostics.Debug.Assert(Boolean condition, String message, String detailMessage)
   at System.Diagnostics.Debug.Assert(Boolean condition, String message)
   at ICSharpCode.Decompiler.CSharp.Transforms.IntroduceUsingDeclarations.Run(AstNode rootNode, TransformContext context) in E:\Programming\RiderProjects\ILSpy\ICSharpCode.Decompiler\CSharp\Transforms\IntroduceUsingDeclarations.cs:line 57
   at ICSharpCode.Decompiler.CSharp.CSharpDecompiler.RunTransforms(AstNode rootNode, DecompileRun decompileRun, ITypeResolveContext decompilationContext) in E:\Programming\RiderProjects\ILSpy\ICSharpCode.Decompiler\CSharp\CSharpDecompiler.cs:line 564
   at ICSharpCode.Decompiler.CSharp.CSharpDecompiler.Decompile(IEnumerable`1 definitions) in E:\Programming\RiderProjects\ILSpy\ICSharpCode.Decompiler\CSharp\CSharpDecompiler.cs:line 1088
   at ICSharpCode.Decompiler.CSharp.CSharpDecompiler.Decompile(EntityHandle[] definitions) in E:\Programming\RiderProjects\ILSpy\ICSharpCode.Decompiler\CSharp\CSharpDecompiler.cs:line 1004
   at ICSharpCode.ILSpy.CSharpLanguage.DecompileType(ITypeDefinition type, ITextOutput output, DecompilationOptions options) in E:\Programming\RiderProjects\ILSpy\ILSpy\Languages\CSharpLanguage.cs:line 334
   at ICSharpCode.ILSpy.TreeNodes.TypeTreeNode.Decompile(Language language, ITextOutput output, DecompilationOptions options) in E:\Programming\RiderProjects\ILSpy\ILSpy\TreeNodes\TypeTreeNode.cs:line 132
   at ICSharpCode.ILSpy.TextView.DecompilerTextView.DecompileNodes(DecompilationContext context, ITextOutput textOutput) in E:\Programming\RiderProjects\ILSpy\ILSpy\TextView\DecompilerTextView.cs:line 914
   at ICSharpCode.ILSpy.TextView.DecompilerTextView.<>c__DisplayClass52_0.<DecompileAsync>b__0() in E:\Programming\RiderProjects\ILSpy\ILSpy\TextView\DecompilerTextView.cs:line 884

After some debugging the issue seems to be caused to the type replacement from a MetadataTypeDefinition to a SpecialType occurring here:

ILSpy/ICSharpCode.Decompiler/TypeSystem/MetadataModule.cs

Line 398 in 9abc2b9

ty = ApplyAttributeTypeVisitor.ApplyAttributesToType(ty, Compilation, typeAttributes, metadata, customOptions, nullableContext);

This means that the call to GetDefinition in ResolveEntity will return null when asked to resolve the IntPtr definition.

ILSpy/ICSharpCode.Decompiler/TypeSystem/MetadataModule.cs

Line 758 in 9abc2b9

return ResolveType(entityHandle, context).GetDefinition();

ResolveEntity is called by RequiredNamespaceCollector but due to the null return value, RequiredNamespaceCollector is unable to collect the true required namespace set.

ILSpy/ICSharpCode.Decompiler/CSharp/RequiredNamespaceCollector.cs

Line 206 in cd3d23e

CollectNamespaces(module.ResolveEntity(entity, genericContext), module, namespaces);

Details

• ILSpy compiled from source code (bdb3235)