IgnoresAccessChecksTo Generator (MSBuild)

The IgnoresAccessChecksToAttribute is the reverse of the InternalsVisibleToAttribute - it allows an assembly to declare assemblies whose internals would be visible to it. The attribute class isn't declared in the BCL but is recognized by the CLR (Desktop >= 4.6 and Core), i.e. you can declare it in your code and it would work.

Since there's currently no compiler support for this attribute (I've submitted a PR to Roslyn), this package can be used as a workaround. It generates reference assemblies where all the internal types & members become public, and adds a C# file with the attribute and its instances.

Usage

Just add the package and define IgnoresAccessChecksTo items with the assemblies you need access to.

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

  <ItemGroup>
    <IgnoresAccessChecksTo Include="AssemblyToGrantAccessTo1" />
    <IgnoresAccessChecksTo Include="AssemblyToGrantAccessTo2" />
    <IgnoresAccessChecksToExcludeTypeName Include="Namespace.TypeName" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="IgnoresAccessChecksToGenerator" Version="0.8.0" PrivateAssets="All" />
  </ItemGroup>

</Project>

Excluding types

Use IgnoresAccessChecksToExcludeTypeName to keep specific types from being publicized. By default an exclusion applies to every assembly being processed. To scope an exclusion to a single assembly, add the Assembly metadata:

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

  <ItemGroup>
    <IgnoresAccessChecksTo Include="AssemblyToGrantAccessTo1" />
    <IgnoresAccessChecksTo Include="AssemblyToGrantAccessTo2" />

    <!-- Excluded from every processed assembly -->
    <IgnoresAccessChecksToExcludeTypeName Include="Namespace.TypeName" />

    <!-- Excluded only from AssemblyToGrantAccessTo1 -->
    <IgnoresAccessChecksToExcludeTypeName Include="Namespace.OtherTypeName" Assembly="AssemblyToGrantAccessTo1" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="IgnoresAccessChecksToGenerator" Version="0.8.0" PrivateAssets="All" />
  </ItemGroup>

</Project>

Omitting the attribute definition

When set to true, the generator will not emit the IgnoresAccessChecksToAttribute class definition in the generated file. This is useful when you already have the attribute defined elsewhere in your project (for example, when multiple packages use the same attribute).

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

  <PropertyGroup>
    <IgnoresAccessChecksToOmitAttributeDefinition>true</IgnoresAccessChecksToOmitAttributeDefinition>
  </PropertyGroup>

  <ItemGroup>
    <IgnoresAccessChecksTo Include="AssemblyToGrantAccessTo" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="IgnoresAccessChecksToGenerator" Version="0.8.0" PrivateAssets="All" />
  </ItemGroup>

</Project>

Using with project references

If you want to ignore access checks to an assembly coming from a ProjectReference instead of a PackageReference, you'll need to set the CompileUsingReferenceAssemblies property to false.

<PropertyGroup>
  <CompileUsingReferenceAssemblies>false</CompileUsingReferenceAssemblies>
</PropertyGroup>