[0.10.0 netstandard] System.MissingMethodException : Method not found: 'Int32 Mono.Cecil.MetadataReader.ReadCodeSize(Mono.Cecil.MethodDefinition)'.

[SteveGilham]

This is a change of behaviour since 0.10-beta7 -- loading an assembly built with mcs with a .mdb symbol file used to work quite happily from a .net core process the same as from old-fashioned .net. Old-fashioned .net still works with 0.10 final, but now using a .net core process to load the same assembly, a System.MissingMethodException with this stack trace emerges

Result StackTrace:	
at Mono.Cecil.Mdb.MdbReader.<>c.<ReadCodeSize>b__7_0(MethodDefinition m, MetadataReader reader)
   at Mono.Cecil.ModuleDefinition.Read[TItem,TRet](TItem item, Func`3 read)
   at Mono.Cecil.Mdb.MdbReader.Read(MethodDefinition method)
   at Mono.Cecil.Cil.CodeReader.ReadMethodBody()
   at Mono.Cecil.Cil.CodeReader.ReadMethodBody(MethodDefinition method)
   at Mono.Cecil.ModuleDefinition.Read[TItem,TRet](TRet& variable, TItem item, Func`3 read)
   at Mono.Cecil.MethodDefinition.get_Body()

[jbevain]

How weird. Thanks for reporting this. You're using both the Mono.Cecil.dll and Mono.Cecil.Mdb.dll from the lib/netstandard1.3 nuget?

[SteveGilham]

Being a .net core app, it just says <PackageReference Include="Mono.Cecil" Version="0.10.0" /> in the project file, so I'm assuming that doesn't have its wires crossed.

Here's an assembly that shows the issue : Sample1.zip

[jbevain]

Thanks, I'll have a look pronto.

[jbevain]

This actually looks like #495.

[jbevain]

The code looks alright, the method that is called is there, but is internal, which is why we have an InternalsVisibleTo between Mono.Cecil and Mono.Cecil.Mdb

[jbevain]

The reason why it changed between the beta7 and the final is b4f4571 that introduced the call.

[jbevain]

@SteveGilham I can't seem to repro.

I created a new dotnet project:

dotnet new console
dotnet add package Mono.Cecil

Modified the csproj so that it reads:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>netcoreapp2.0;net46</TargetFrameworks>
  </PropertyGroup>

  <ItemGroup>
    <None Include="Sample1.exe">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Include="Sample1.exe.mdb">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Mono.Cecil" Version="0.10.0" />
  </ItemGroup>

</Project>

Wrote:

using System;
using System.Linq;

using Mono.Cecil;

namespace _500repro
{
  class Program
  {
    static void Main(string[] args)
    {
      Console.WriteLine("Hello World!");
      
      using (var module = ModuleDefinition.ReadModule("Sample1.exe", new ReaderParameters { ReadSymbols = true }))
      {
        Console.WriteLine($"Module has symbols: {module.HasSymbols}");

        foreach (var method in module.GetTypes().SelectMany(t => t.Methods).Where(m => m.HasBody))
        {
          Console.WriteLine($"On method: {method.FbullName}");
          Console.WriteLine(method.Body);
        }
      }
    }
  }
}

And when running for both frameworks it runs without crashing on getting the method body.

Do you have a way to reproduce this?

[SteveGilham]

I'm in the process of cutting down to a simple repro case. Will update later.

[SteveGilham]

I've found the culprit. It's the NUnit3TestAdapter v 3.10.0 which includes also Mono.Cecil, from beta6

[assembly: AssemblyInformationalVersion("0.10.0.0-beta6")]
[assembly: AssemblyTitle("Mono.Cecil")]

and that's going to be loaded ahead of any of my code.

[SimonCropp]

It's the NUnit3TestAdapter v 3.10.0 which includes also Mono.Cecil, from beta6

@SteveGilham one of reasons i moved to xunit