Warnings when building multi-target projects

[neoeinstein]

<Project Sdk="FSharp.NET.Sdk;Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFrameworks>net40;netstandard1.6</TargetFrameworks>
  </PropertyGroup>
  <ItemGroup>
    <Compile Include="Lib.fs" />
  </ItemGroup>
  <ItemGroup>
    <PackageReference Include="FSharp.NET.Sdk" Version="1.*" PrivateAssets="All" />
    <PackageReference Include="FSharp.Core" Version="4.*" />
  </ItemGroup>
</Project>

with a minimal library:

module Lib = let f x = f x

Gives the following warning:

C:\Program Files\dotnet\sdk\1.0.0-rc4-004842\Microsoft.Common.CrossTargeting.targets(116,3): warning MSB4011: "C:\Program Files\dotnet\sdk\1.0.0-rc4-004842\15.0\Microsoft.Common.targets\ImportAfter\Microsoft.NuGet.ImportAfter.targets" cannot be imported again. It was already imported at "C:\Program Files\dotnet\sdk\1.0.0-rc4-004842\Microsoft.Common.CurrentVersion.targets (5733,3)". This is most likely a build authoring error. This subsequent import will be ignored. [C:\dev\github.com\org\proj\src\Proj\Proj.fsproj]

C:\Program Files\dotnet\sdk\1.0.0-rc4-004842\Microsoft.Common.CrossTargeting.targets(145,3): warning MSB4011: "C:\dev\github.com\org\proj\src\Proj\obj\Proj.fsproj.nuget.g.targets" cannot be imported again. It was already imported at "C:\Program Files\dotnet\sdk\1.0.0-rc4-004842\Microsoft.Common.targets (127,3)". This is most likely a build authoring error. This subsequent import will be ignored. [C:\dev\github.com\org\proj\src\Proj\Proj.fsproj]

This is non-blocking, and only produces noise during builds. I am using SDK 1.0.0-rc4-004842.

[enricosada]

Yes, is an old one after preview3, it really is a build authoring error as warning say.

Can be diagnosed with dotnet msbuild /pp who merge all imported targets/props in a single proj, so should be possibile to understand why. But afaik is annoying with how crossTargeting is done in FSharp.Sdk the part embedded in sdk, the Sdk="FSharp.NET.Sdk

[neoeinstein]

As recommended, but this looks ominous:

> dotnet msbuild /pp:out.xml

Process is terminated due to StackOverflowException.

[enricosada]

@neoeinstein well, that's a msbuild bug, so please report to https://github.com/microsoft/msbuild

The command is just dotnet msbuild /pp.
You can save to file using console redirection as dotnet msbuild /pp > out.xml

[enricosada]

That said, dont waste lot of time on that, probably it will require an update to fsharp sdk package embedded in cli. And cannot be done for rtm for sure

[dustinmoris]

Ionide also doesn't work when having more than one build target. Logged it under ionide/ionide-vscode-fsharp#435.

[enricosada]

Closing, will be fixed in sdk 2.0 (cannot be fixed in 1.0 atm)

The ionide/fsac bug is tracked in respective repos

[TheAngryByrd]

For anyone coming to this with 1.0 tooling you can pass /warnasmessage:MSB4011 to suppress the warning.

dotnet build /warnasmessage:MSB4011

I don't however know how to make this work for dotnet run