多目标`net461`和`netcoreapp2.0`

Question

I have a command line .NET application that should compile against only ported .NET Core components when built as a .NET core app, but can additionally reference legacy .NET framework modules when built that way.

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>net461;netcoreapp2.0</TargetFrameworks>
    <ProjectGuid>{48B4C337-CD13-4826-B6A1-DA97CE71511B}</ProjectGuid>
    <RootNamespace>Microsoft.Pc</RootNamespace>
    <AssemblyName>Pc</AssemblyName>
    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
    <OutputPath>$(PSdkFolder)\Binaries</OutputPath>
  </PropertyGroup>
  <ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp2.0'">
    <ProjectReference Include="..\CompilerCore\CompilerCore.csproj" />
  </ItemGroup>
  <ItemGroup Condition="'$(TargetFramework)' == 'net461'">
    <ProjectReference Include="..\CompilerCore\CompilerCore.csproj" />
    <ProjectReference Include="..\LegacyCompiler\LegacyCompiler.csproj" />
    <ProjectReference Include="..\CompilerService\CompilerService.csproj" />
  </ItemGroup>
</Project>

Despite this, I get these errors

"D:\Source\Repos\P\P.sln" (default target) (1) ->
"D:\Source\Repos\P\Src\Pc\CommandLine\CommandLine.csproj.metaproj" (default target) (20) ->
"D:\Source\Repos\P\Src\Pc\CommandLine\CommandLine.csproj" (default target) (21) ->
"D:\Source\Repos\P\Src\Pc\CommandLine\CommandLine.csproj" (Build target) (21:3) ->
(_GetProjectReferenceTargetFrameworkProperties target) ->
  C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\MSBuild\15.0\bin\Microsoft.Common.CurrentVersion.targets(1601,5): error : Project 'D:\Source\Repos\P\Src\Pc\LegacyCompiler\LegacyCompiler.csproj' targets 'net461'. It cannot be referenced by a project that targets '.NETCoreApp,Version=v2.0'. [D:\Source\Repos\P\Src\Pc\CommandLine\CommandLine.csproj]
  C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\MSBuild\15.0\bin\Microsoft.Common.CurrentVersion.targets(1601,5): error : Project 'D:\Source\Repos\P\Src\Pc\CompilerService\CompilerService.csproj' targets 'net461'. It cannot be referenced by a project that targets '.NETCoreApp,Version=v2.0'. [D:\Source\Repos\P\Src\Pc\CommandLine\CommandLine.csproj]

Why is it complaining that LegacyCompiler.csproj targets 'net461' while CommandLine targets '.NETCoreApp,Version=v2.0' when that dependency should be excluded in this case?

Update: these are the .csproj files for the other projects. As this project is open-source, I'm posting links to the files:

CompilerCore.csproj

CommandLine.csproj

LegacyCompiler.csproj

Answer 1

您应该将.Net Standard类库与.Net Core和.Net 4.6.1支持的版本一起使用（我可能从您的.csproj文件中猜到）。