Running dotnet build on a project that targets both net451 and netcoreapp1.0 fails

[prafullbhosale]

Steps to reproduce

Run dotnet restore and dotnet build on the below project

<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" />
  
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>net451;netcoreapp1.0</TargetFrameworks>
    <RunTimeIdentifier Condition="'$(TargetFramework)' == 'net451'">win7-x86</RunTimeIdentifier>
  </PropertyGroup>

  <ItemGroup>
    <Compile Include="**\*.cs" />
    <EmbeddedResource Include="**\*.resx" />
  </ItemGroup>

  <ItemGroup Condition=" '$(TargetFramework)' == 'net451' ">
    <Reference Include="System" />
    <Reference Include="Microsoft.CSharp" />
    <PackageReference Include="Microsoft.NET.Sdk">
      <Version>1.0.0-alpha-20161104-2</Version>
      <PrivateAssets>All</PrivateAssets>
    </PackageReference>
  </ItemGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.Extensions.CommandLineUtils">
      <Version>1.0.1</Version>
    </PackageReference>
  </ItemGroup>
  <ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp1.0' ">
    <PackageReference Include="Microsoft.NETCore.App">
      <Version>1.0.1</Version>
    </PackageReference>
    <PackageReference Include="Microsoft.NET.Sdk">
      <Version>1.0.0-alpha-20161104-2</Version>
      <PrivateAssets>All</PrivateAssets>
    </PackageReference>
  </ItemGroup>
  
  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
</Project>

using Microsoft.Extensions.CommandLineUtils;
using System;

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Hello World!");
        var app = new CommandLineApplication();
    }
}

Expected behavior

Build succeeds.

Actual behavior

Error

Program.cs(1,17): error CS0234: The type or namespace name 'Extensions' does not exist in the namespace 'Microsoft' (are you missing an assembly reference?) [C:\Users\prbhosal\Documents\Visual Studio 2017\Projects\ConsoleApp1\ConsoleApp1\ConsoleApp1.csproj]

Workaround

Run dotnet msbuild /t:Restore /p:TargetFramework=net451 and then run dotnet build

Environment data

dotnet --info output:

.NET Command Line Tools (1.0.0-preview4-004117)

Product Information:
Version: 1.0.0-preview4-004117
Commit SHA-1 hash: 923320b

Runtime Environment:
OS Name: Windows
OS Version: 10.0.14393
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\1.0.0-preview4-004117

cc @mlorbetske @pranavkm

[natemcmaster]

+1. Command line restore/build is the only way to build. Restore/build within VS2017 breaks. With CLI 1.0.0-preview4-004233, the error is:

'C:\dev\TestProj\obj\project.assets.json' doesn't have a target for '.NETFramework,Version=v4.5.1/win7-x64'. Ensure you have restored this project for TargetFramework='net451' and RuntimeIdentifier='win7-x64'. TestProj C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\Sdks\Microsoft.NET.Sdk\build\Microsoft.NET.Sdk.targets 119

[prafullbhosale]

Just in case anybody else hits this, there is another simple workaround for this. Just need to flip the condition to exclude the RuntimeIdentifier property from all other TFMs

<RunTimeIdentifier Condition="'$(TargetFramework)' != 'netcoreapp1.0'">win7-x86</RunTimeIdentifier>

[nguerrera]

Closing as duplicate of #396, the plan for which will fix this.