No support for duplicated types?

[ajaskiewiczpl]

ILMerge supports the /allowDup command line argument to allow duplicated types. However when I try to use ILMerge.Fody, in runtime I get the error System.BadImageFormatException Duplicate type with name 'System.Web.Http.Error' in assembly [...]. Is there a reason why it's not supported?

[tom-englert]

I did not see a use case for this. When would you have two assemblies having e.g. System.Web.Http already embedded?

[tom-englert]

No feedback, closed as stale

[otuncelli]

I'd like to suggest reopening this issue.

Introduced with C# 7.2, readonly structs are causing System.Runtime.CompilerServices.IsReadOnlyAttribute and Microsoft.CodeAnalysis.EmbeddedAttribute types to be embedded in the resulting assembly. And they cause this issue if multiple assemblies are containing these.

Note: In my tests, netstandard2.1 and beyond are not affected by this issue.

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Hello World!");
    }

    public readonly struct Test
    {
    }
}

ILSpy of Assembly:

Thanks.

[tom-englert]

@otuncelli that should be already working. Anything with the [Embedded] attribute is replaced with the existing target type. I'm using this heavily for assemblies with nullable reference types. Can you provide a sample where this is not working?

[otuncelli]

I'm currently working with PdfPig Library. It contains these readonly structs in its different assemblies.

Edit: It seems to happen only when I use NamespacePrefix

The error message I get when I try debugging:

ILSpy of resulting assembly:

My Configuration:

<Weavers xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="FodyWeavers.xsd">
    <ILMerge NamespacePrefix="PdfFileTypePlugin">
        <IncludeAssemblies>PDFiumSharp|UglyToad.PdfPig.Core|UglyToad.PdfPig|UglyToad.PdfPig.DocumentLayoutAnalysis|UglyToad.PdfPig.Fonts|UglyToad.PdfPig.Package|UglyToad.PdfPig.Tokenization|UglyToad.PdfPig.Tokens</IncludeAssemblies>
        <FullImport>true</FullImport>
    </ILMerge>
</Weavers>

[tom-englert]

@otuncelli can you try V 1.18?

[otuncelli]

Solved! Thank you very much.

[tom-englert]

It seems to happen only when I use NamespacePrefix

That was the key information