WPF App Using new csproj format

Question

I am experimenting with migrating a WPF project, defined using the old csproj format, to the new format under VS 2017.

I was able to get most of the way to a successful build using information I found at How-to migrate Wpf projects to the new VS2017 format.

But I'm stuck at getting past this error:

error CS5001: Program does not contain a static 'Main' method suitable for an entry point

My new-style csproj file is as follows:

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

  <PropertyGroup>
    <LanguageTargets>$(MSBuildExtensionsPath)\$(VisualStudioVersion)\Bin\Microsoft.CSharp.targets</LanguageTargets>
    <OutputType>winexe</OutputType>
    <TargetFramework>net47</TargetFramework>
    <ApplicationIcon />
    <OutputTypeEx>winexe</OutputTypeEx>
    <StartupObject />
  </PropertyGroup>

  <ItemGroup>
    <EmbeddedResource Update="Properties\Resources.resx" Generator="ResXFileCodeGenerator" LastGenOutput="Resources.Designer.cs" />
    <Compile Update="Properties\Resources.Designer.cs" DesignTime="True" AutoGen="True" DependentUpon="Resources.resx" />
    <Compile Update="Settings.Designer.cs" AutoGen="True" DependentUpon="Settings.settings" />
    <None Update="Settings.settings" LastGenOutput="Settings.Designer.cs" Generator="SettingsSingleFileGenerator" />

    <Page Include="**\*.xaml" SubType="Designer" Generator="MSBuild:Compile" />
    <Compile Update="**\*.xaml.cs" SubType="Designer" DependentUpon="%(Filename)" />

    <Resource Include="assets\*.*" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Autofac" Version="4.6.0" />
    <PackageReference Include="Autofac.Extras.CommonServiceLocator" Version="4.0.0" />
    <PackageReference Include="Extended.Wpf.Toolkit" Version="3.0.0" />
    <PackageReference Include="Hardcodet.NotifyIcon.Wpf" Version="1.0.8" />
    <PackageReference Include="MaterialDesignColors" Version="1.1.3" />
    <PackageReference Include="MaterialDesignThemes" Version="2.3.0.823" />
    <PackageReference Include="MvvmLightLibs" Version="5.3.0" />
    <PackageReference Include="Serilog" Version="2.4.0" />
    <PackageReference Include="Serilog.Sinks.RollingFile" Version="3.3.0" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\..\WPFUtilities\J4JUI\J4JUI.csproj" />
  </ItemGroup>

  <ItemGroup>
    <Reference Include="System.ComponentModel.DataAnnotations" />
  </ItemGroup>

  <Import Project="$(MSBuildSDKExtrasTargets)" Condition="Exists('$(MSBuildSDKExtrasTargets)')" />
</Project>

How do I configure the csproj file so that entry point gets built?

Update

Based on the tip about ApplicationDefinition I was able to get the project to compile. I could not set ApplicationDefinition in the BuildAction -- it was not one of the choices -- but had to edit the csproj file manually to include it. Here's the working version:

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

  <PropertyGroup>
    <LanguageTargets>$(MSBuildExtensionsPath)\$(VisualStudioVersion)\Bin\Microsoft.CSharp.targets</LanguageTargets>
    <OutputType>winexe</OutputType>
    <TargetFramework>net47</TargetFramework>
    <ApplicationIcon />
    <OutputTypeEx>winexe</OutputTypeEx>
    <StartupObject />
  </PropertyGroup>

  <ItemGroup>
    <EmbeddedResource Update="Properties\Resources.resx" Generator="ResXFileCodeGenerator" LastGenOutput="Resources.Designer.cs" />
    <Compile Update="Properties\Resources.Designer.cs" DesignTime="True" AutoGen="True" DependentUpon="Resources.resx" />
    <Compile Update="Settings.Designer.cs" AutoGen="True" DependentUpon="Settings.settings" />
    <None Update="Settings.settings" LastGenOutput="Settings.Designer.cs" Generator="SettingsSingleFileGenerator" />

    <Page Include="**\*.xaml" SubType="Designer" Generator="MSBuild:Compile" Exclude="App.xaml" />
    <Compile Update="**\*.xaml.cs" SubType="Designer" DependentUpon="%(Filename)" />

    <Resource Include="assets\*.*" />

    <ApplicationDefinition Include="App.xaml">
      <Generator>MsBuild:Compile</Generator>
      <SubType>Designer</SubType>
    </ApplicationDefinition>

  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Autofac" Version="4.6.0" />
    <PackageReference Include="Autofac.Extras.CommonServiceLocator" Version="4.0.0" />
    <PackageReference Include="Extended.Wpf.Toolkit" Version="3.0.0" />
    <PackageReference Include="Hardcodet.NotifyIcon.Wpf" Version="1.0.8" />
    <PackageReference Include="MaterialDesignColors" Version="1.1.3" />
    <PackageReference Include="MaterialDesignThemes" Version="2.3.0.823" />
    <PackageReference Include="MvvmLightLibs" Version="5.3.0" />
    <PackageReference Include="Serilog" Version="2.4.0" />
    <PackageReference Include="Serilog.Sinks.RollingFile" Version="3.3.0" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\..\WPFUtilities\J4JUI\J4JUI.csproj" />
  </ItemGroup>

  <ItemGroup>
    <Reference Include="System.ComponentModel.DataAnnotations" />
  </ItemGroup>

  <Import Project="$(MSBuildSDKExtrasTargets)" Condition="Exists('$(MSBuildSDKExtrasTargets)')" />
</Project>

Note also the Exclude filter on the directive. It's necessary to keep MSBuild from attempting to compile App.xaml.cs twice.

Answer 1

You need to set the Build Action of App.xaml to ApplicationDefinition. The result is the following item in your csproj file:

<ApplicationDefinition Include="App.xaml">
  <Generator>MSBuild:Compile</Generator>
  <SubType>Designer</SubType>
</ApplicationDefinition>