Make Paket build on a clean installation:

* acquire msbuild via RoslynTools.MSBuild
* acquire reference assemblies via a self-built package based on https://github.com/jaredpar/xcopy-msbuild
* use a fork of dotnet-mergenupkg which was recompiled against netcoreapp2.0 (original was netcoreapp1.0) to remove dependency on 1.x runtime

Directory.Build.props

@@ -0,0 +1,5 @@
+<Project>
+ <PropertyGroup>
+	<TargetFrameworkRootPath>$(MSBuildThisFileDirectory)packages\build\0x53A.ReferenceAssemblies.Paket\tools\Framework</TargetFrameworkRootPath>
+ </PropertyGroup>
+</Project>

build.cmd

@@ -5,4 +5,7 @@ if errorlevel 1 (
   exit /b %errorlevel%
 )
 
+set MSBUILD=packages\build\RoslynTools.MSBuild\tools\msbuild
+set PATH=%PATH%;packages\build\RoslynTools.MSBuild\tools\msbuild
+
 packages\build\FAKE\tools\FAKE.exe build.fsx %*

build.fsx

@@ -364,7 +364,7 @@ Target "MergeDotnetCoreIntoNuget" (fun _ ->
 
     let runTool = runCmdIn "tools" dotnetExePath
 
-    runTool """mergenupkg --source "%s" --other "%s" --framework netstandard1.6 """ nupkg netcoreNupkg
+    runTool """0x53A-mergenupkg --source "%s" --other "%s" --framework netstandard1.6 """ nupkg netcoreNupkg
 )
 
 Target "PublishNuGet" (fun _ ->

build.sh

@@ -7,7 +7,8 @@ then
   if [ $exit_code -ne 0 ]; then
   	exit $exit_code
   fi
-
+  MSBUILD=packages\build\RoslynTools.MSBuild\tools\msbuild
+  PATH=$PATH;$MSBUILD
   packages/build/FAKE/tools/FAKE.exe $@ --fsiargs -d:MONO build.fsx 
 else
   mono .paket/paket.exe restore
@@ -27,6 +28,8 @@ else
     fi
     exit $exit_code
   fi
+  MSBUILD=packages\build\RoslynTools.MSBuild\tools\msbuild
+  PATH=$PATH;$MSBUILD
   mono packages/build/FAKE/tools/FAKE.exe $@ --fsiargs -d:MONO build.fsx 
 fi
 

paket.dependencies

@@ -44,3 +44,10 @@ group Build
   nuget ILRepack
 
   github fsharp/FAKE modules/Octokit/Octokit.fsx
+
+  nuget 0x53A.ReferenceAssemblies.Paket 0.2.0
+
+  source https://dotnet.myget.org/F/roslyn-tools/api/v3/index.json
+  nuget RoslynTools.MSBuild prerelease
+  # Note: RoslynTools.ReferenceAssemblies does not contain the required reference assemblies for net45, so I created 0x53A.ReferenceAssemblies.Paket. It is much smaller, anyway.
+  #nuget RoslynTools.ReferenceAssemblies prerelease

paket.lock

@@ -1136,6 +1136,7 @@ GROUP Build
 CONTENT: NONE
 NUGET
   remote: https://www.nuget.org/api/v2
+    0x53A.ReferenceAssemblies.Paket (0.2)
     FAKE (4.63)
     FSharp.Compiler.Service (13.0)
       FSharp.Core (>= 4.1.17) - restriction: >= netstandard1.6
@@ -1818,6 +1819,8 @@ NUGET
       FSharp.Compiler.Service (>= 13.0 < 14.0)
       Microsoft.AspNet.Razor (>= 3.2.3 < 4.0)
       System.ValueTuple (>= 4.3.1 < 5.0)
+  remote: https://dotnet.myget.org/F/roslyn-tools/api/v3/index.json
+    RoslynTools.MSBuild (0.4.0-alpha)
 GITHUB
   remote: fsharp/FAKE
     modules/Octokit/Octokit.fsx (291f58cc70aba6dd871cf18e66d2d88357e4f208)

src/Directory.Build.props

@@ -1,4 +1,6 @@
 <Project>
+  <!-- MSBuild only includes the first Directory.Build.props, so we need to manually include the root one -->
+  <Import Project="$(MSBuildThisFileDirectory)..\Directory.Build.props" />
   <PropertyGroup>
     <DebugType>portable</DebugType>
   </PropertyGroup>

tools/tools.fsproj

@@ -3,7 +3,7 @@
     <TargetFramework>netstandard1.6</TargetFramework>
   </PropertyGroup>
   <ItemGroup>
-    <DotNetCliToolReference Include="dotnet-mergenupkg" Version="1.0.*" />
+    <DotNetCliToolReference Include="dotnet-0x53A-mergenupkg" Version="1.0.*" />
   </ItemGroup>
   <Import Project="..\.paket\Paket.Restore.targets" />
 </Project>