.NET 5 RC2: "Analyze/Used By" throws BadImageFormatException

[albahari]

Steps to reproduce

1. Load the .NET 5 RC2 assemblies
2. Navigate to the System.Runtime.CompilerServices.CallConvCdecl type
3. Ctrl+R for Analyze, expand 'Used By'

Error message shown

System.BadImageFormatException: Expected signature header for 'Property' or 'Method', but found '9' (0x09).
   at System.Reflection.Metadata.Ecma335.SignatureDecoder`2.CheckMethodOrPropertyHeader(SignatureHeader header)
   at System.Reflection.Metadata.Ecma335.SignatureDecoder`2.DecodeMethodSignature(BlobReader& blobReader)
   at System.Reflection.Metadata.Ecma335.SignatureDecoder`2.DecodeType(BlobReader& blobReader, Boolean allowTypeSpecifications, Int32 typeCode)
   at System.Reflection.Metadata.Ecma335.SignatureDecoder`2.DecodeType(BlobReader& blobReader, Boolean allowTypeSpecifications)
   at System.Reflection.Metadata.Ecma335.SignatureDecoder`2.DecodeTypeSequence(BlobReader& blobReader)
   at System.Reflection.Metadata.StandaloneSignature.DecodeLocalSignature[TType,TGenericContext](ISignatureTypeProvider`2 provider, TGenericContext genericContext)
   at ICSharpCode.Decompiler.TypeSystem.MetadataModule.DecodeLocalSignature(StandaloneSignatureHandle handle, GenericContext genericContext)
   at ICSharpCode.ILSpy.Analyzers.Builtin.TypeUsedByAnalyzer.ScanMethodBody(TypeDefinitionUsedVisitor visitor, IMethod method, MethodBodyBlock methodBody, AnalyzerContext context)
   at ICSharpCode.ILSpy.Analyzers.Builtin.TypeUsedByAnalyzer.<ScanType>d__1.MoveNext()
   at ICSharpCode.ILSpy.Analyzers.Builtin.TypeUsedByAnalyzer.<Analyze>d__0.MoveNext()
   at ICSharpCode.ILSpy.Analyzers.AnalyzerSearchTreeNode.<FetchChildren>d__10.MoveNext()
   at ICSharpCode.ILSpy.TreeNodes.ThreadingSupport.<>c__DisplayClass5_0.<LoadChildren>b__0()
   at System.Threading.Tasks.Task`1.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()

Details

• Product in use: ILSpy version 6.2.1.6137

[siegfriedpammer]

This is because ILSpy does not yet use a version of System.Reflection.Metadata that supports the new function pointer signature extensions. I believe @dgrunwald recently experimented with updating to a preview of SRM.

[dgrunwald]

This particular crash should already be fixed in ILSpy master, as we've updated to a pre-release version of SRM 5 there.

However in general I think the analyzer should be catching BadImageFormatException and continue analyzing as much as possible. (such exceptions can also happen with obfuscated assemblies)