Directory.Build.targets

<Project>
  <!-- Polyfill source files compile ONLY in AdocNet.Ast (the leaf assembly).
       All other multi-targeted projects access polyfill types via InternalsVisibleTo.
       This avoids extension method ambiguity when multiple assemblies each define the same types. -->
  <ItemGroup Condition="'$(TargetFrameworks)' != '' and '$(RootNamespace)' == 'AdocNet.Ast'">
    <Compile Include="$(MSBuildThisFileDirectory)src\Polyfills\*.cs" LinkBase="Polyfills" />
  </ItemGroup>

  <!-- Global usings for the compatibility namespace — included in ALL multi-targeted projects
       so extension methods from the polyfills (compiled in AdocNet.Ast) are accessible. -->
  <ItemGroup Condition="'$(TargetFrameworks)' != '' and '$(RootNamespace)' != 'AdocNet.Ast'">
    <Compile Include="$(MSBuildThisFileDirectory)src\Polyfills\GlobalUsings.ns20.cs" LinkBase="Polyfills" />
  </ItemGroup>

  <!-- Suppress CS0436 (type conflicts with imported type) for NS2.0 polyfills.
       This is expected when multiple assemblies in the same solution each compile
       the same internal polyfill types (Index, Range, IsExternalInit, etc.).
       The compiler resolves correctly by using the locally defined type. -->
  <PropertyGroup Condition="'$(TargetFrameworks)' != ''">
    <NoWarn>$(NoWarn);CS0436;CS1685</NoWarn>
  </PropertyGroup>
</Project>