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Error CS0012 when building against v3 #2564

Closed nickrandolph closed 6 years ago

nickrandolph commented 6 years ago

Description

Upgrading MvvmCross to v3 of XF we ran into issue where we're seeing the following error. error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'. MvvmCross is multi-targeted and I suspect that this is related to when it's building the Android target

Steps to Reproduce

  1. Grab the branch of MvvmCross referenced in this PR https://github.com/MvvmCross/MvvmCross/pull/2831
  2. Attempt to build and run

Expected Behavior

Should build with no errors

Actual Behavior

~117 errors similar to: error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'.

Basic Information

---------------------------------- Full VS Info -----------------------------------------------------

Microsoft Visual Studio Professional 2017 Preview Version 15.7.0 Preview 5.0 VisualStudio.15.Preview/15.7.0-pre.5.0+27625.0 Microsoft .NET Framework Version 4.7.02556

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Azure App Service Tools v3.0.0 15.0.40424.0 Azure App Service Tools v3.0.0

Azure Data Lake Node 1.0 This package contains the Data Lake integration nodes for Server Explorer.

Azure Data Lake Tools for Visual Studio 2.3.3000.4 Microsoft Azure Data Lake Tools for Visual Studio

Azure Functions and Web Jobs Tools 15.0.40424.0 Azure Functions and Web Jobs Tools

Azure Stream Analytics Tools for Visual Studio 2.3.3000.4 Microsoft Azure Stream Analytics Tools for Visual Studio

C# Tools 2.8.0-beta4-62825-01. Commit Hash: 941725e0ef87022f098789c0cdba2f5b42816e20 C# components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

Common Azure Tools 1.10 Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.

Fabric.DiagnosticEvents 1.0 Fabric Diagnostic Events

GitHub.VisualStudio 2.5.1.2234 A Visual Studio Extension that brings the GitHub Flow into Visual Studio.

JavaScript Language Service 2.0 JavaScript Language Service

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VisualStudio.Mac 1.0 Mac Extension for Visual Studio

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Xamarin 4.10.0.440 (943b34d9d) Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.

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Xamarin.Android SDK 8.3.0.18 (HEAD/1f8462ef1) Xamarin.Android Reference Assemblies and MSBuild support.

Xamarin.iOS and Xamarin.Mac SDK 11.10.1.174 (f493322) Xamarin.iOS and Xamarin.Mac Reference Assemblies and MSBuild support.

nickrandolph commented 6 years ago

@onovotny have you seen anything like this - looping you in as the father of multi-targeting as I'm guessing it might be related. Seems that for some reason the Android SDK doesn't like our multi-targeted library.

nickrandolph commented 6 years ago

FYI we managed to get v3 working with mvvmcross (see https://github.com/MvvmCross/MvvmCross/pull/2864) thanks to @martijn00. Still not sure exactly what the issue was, probably nuget related we think.

nickrandolph commented 6 years ago

Ok, cancel that. Apparently the 6.1.0 branch of MvvmCross (https://github.com/MvvmCross/MvvmCross/tree/release/6.1.0) now builds for some people. For me it has the same issue described above. I've upgraded to 15.8 preview 1.1, but still seeing same issue

jassmith commented 6 years ago

MvvmCross has fixed this upstream.

nickrandolph commented 6 years ago

@jassmith not sure what you're talking about - is there a PR I missed that fixes this issue? I've been talking with @martijn00 and we're still blocked (as of 3hrs ago)

jassmith commented 6 years ago

I must be misreading this PR?

builttoroamadmin commented 6 years ago

Check the issue though, and my subsequent comment. Please reopen this as it’s a major blocker for us atm

jassmith commented 6 years ago

Can you link me to your comments?

jassmith commented 6 years ago

image

So thats not supposed to work?

jassmith commented 6 years ago

Thats using XF 3.0

jassmith commented 6 years ago

I reprod the issue. Xamarin.Mac doesn't want to accept the multi-targeting with .NET standard (I had mac disabled on my machine for other reasons). Dont multitarget its dll and you're good to go. There is probably a way to coax it into doing multitargeting but it seems not worth the effort.

jassmith commented 6 years ago 
<ItemGroup Condition=" $(TargetFramework.StartsWith('Xamarin.Mac')) ">
   <Reference Include="netstandard" />
</ItemGroup>

You are missing that in your .csproj file. Adding that will make it build. I didn't have Mac enabled the first time hence why it didn't work.

After you add that please close VS, nuke bin/obj and relaunch. Just to be sure old state isn't being kept around.

nickrandolph commented 6 years ago

Ok for me I was seeing the same issue with the Android build. I'll see if adding that reference for Android fixes it there too.

nickrandolph commented 6 years ago

Hey thanks for investigating. I'm sure that I tried something similar to this but perhaps I didn't flush everything properly last time. Anyhow, just did a successful build of Android and Mac and seems to be working (touch wood), so a big thank you!