Exception when assembly doesn't contain `TargetFrameworkId` data

[jaredpar]

Steps to reproduce

Created a C# file called example.cs with the following content:

interface I1 { }

Then run the following command:

> dotnet exe "C:\Program Files\dotnet\sdk\5.0.101\Roslyn\bincore\csc.dll" example.cs /t:library /noconfig

Error message shown

Open the resulting example.dll file in ILSpy and you will get the following error message:

System.ArgumentOutOfRangeException: Index and length must refer to a location within the string.
Parameter name: length
   at System.String.Substring(Int32 startIndex, Int32 length)
   at ICSharpCode.Decompiler.Metadata.DotNetCorePathFinderExtensions.DetectTargetFrameworkId(PEReader assembly, String assemblyPath)
   at ICSharpCode.ILSpy.LoadedAssembly.<GetTargetFrameworkIdAsync>d__6.MoveNext()

Details

• Product in use:ILSpy 6.2.1.6137

[siegfriedpammer]

So your quiz on twitter made ILSpy crash 😄

[jaredpar]

So your quiz on twitter made ILSpy crash

Indeed it did 😄

[siegfriedpammer]

I've fixed the bug by assuming MetadataVersion "4.0" (used as framework version) if it's empty... however, it might be more reasonable to assume framework version 5.0 instead?

[jaredpar]

Think 4.0 is probably better. This can work effectively well in pretty much any framework .

[siegfriedpammer]

Makes sense, thanks!