namespace collision in clr-namespace

• .NET Core Version: 7.0-rc1
• Windows version: 11
• Does the bug reproduce also in WPF for .NET Framework 4.8?: Don’t know, not tested

Problem description: MainWindow.xaml(28, 27): [CS0234] The type or namespace name 'Wpf' does not exist in the namespace 'Comlink.CefSharp' (are you missing an assembly reference?)

This is the error I get, the error itself is “correct”. that namespace does not contain Wpf. However, .NET shouldn’t even be looking in that namespace in the first place, since I have defined an assembly in my xaml file.

to give some more details: /src/View/MainWindow.xaml

<Window 
    x:Class="Comlink.Example.View.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:cefSharp="clr-namespace:CefSharp.Wpf;assembly=CefSharp.Wpf"
    mc:Ignorable="d"
    Title="Comlink examples" 
    Height="450" 
    Width="800"
>
    <cefSharp:ChromiumWebBrowser x:Name="CefSharpBrowser" Address="https://google.com" />
</Window>

/src/View/MainWindow.xaml

using System.Windows;
using Comlink.Core;
using Comlink.CefSharp;

namespace Comlink.Example.View
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Initialize()
        {
            Kaas kaas = new Kaas();
            Proxy<Kaas> proxied = Core.Comlink.Proxy(kaas);
            
            CefSharpBrowser.Expose(kaas);
            dynamic remote2 = Core.Comlink.Wrap<ClientSchema>(CefSharpBrowser.ToEndpoint());
            remote2.SomeMethod("a string value");
        }
    }

    public class Kaas
    {

    }

    public class ClientSchema
    {

    }
}

csproj file

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net7.0-windows</TargetFramework>
    <PublishReadyToRun>true</PublishReadyToRun>
    <UseWPF>true</UseWPF>
    <NoWarn>$(NoWarn);1591</NoWarn>
    <StartupObject>Comlink.Example.View.App</StartupObject>
    <Nullable>enable</Nullable>

    <RuntimeIdentifier Condition="'$(RuntimeIdentifier)' == ''">$(NETCoreSdkRuntimeIdentifier)</RuntimeIdentifier>
    <SelfContained Condition="'$(SelfContained)' == ''">false</SelfContained>
    <Platforms>x64</Platforms>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="CefSharp.Wpf.NETCore" Version="106.0.260" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\Comlink.Core\Comlink.Core.csproj" />
    <ProjectReference Include="..\Comlink.CefSharp\Comlink.CefSharp.csproj" />
  </ItemGroup>

  <ItemGroup>
    <ApplicationDefinition Include="src\View\App.xaml">
      <Generator>MSBuild:Compile</Generator>
      <XamlRuntime>Wpf</XamlRuntime>
      <SubType>Designer</SubType>
    </ApplicationDefinition>
  </ItemGroup>

  <ItemGroup>
    <Page Update="src\View\MainWindow.xaml">
      <Generator>MSBuild:Compile</Generator>
      <XamlRuntime>Wpf</XamlRuntime>
      <SubType>Designer</SubType>
    </Page>
  </ItemGroup>

</Project>

It seems to me that the generated g code in the obj folder is what is causing the naming collision between my referenced project and the package. I don’t really understand why though because I did add the assembly attribute in the xaml file.

If you want to take a deeper look at the source files of this project you can find it in https://github.com/chris-kruining/comlink-sharp/tree/main/Comlink.Example

[miloush]

Because you have a nested namespace, i.e. Comlink.CefSharp.* and CefSharp.*. Then your window is in Comlink.* so everything inside that namespace that refers to simply CefSharp would resolve to Comlink.Cefsharp rather than CefSharp, that is not really a WPF issue and you are unnecessarily making things difficult for yourself.

Related but not very useful to your case is #7125. More interestingly #4014 would probably help you, this is perhaps duplicate of it.

[chris-kruining]

@miloush I have not confirmed this, but if my memory serves me right. The generated code from Xamarin also prefixes everything with global::. maybe it is worth to communicate with that team to discover possible pitfalls for XAML