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 +5,6 @@ if errorlevel 1 (
   exit /b %errorlevel%
 )
 
+set MSBuild=packages\build\RoslynTools.MSBuild\tools\msbuild
+
 packages\build\FAKE\tools\FAKE.exe build.fsx %*

build.sh

@@ -7,7 +7,7 @@ then
   if [ $exit_code -ne 0 ]; then
   	exit $exit_code
   fi
-
+  export MSBuild=packages/build/RoslynTools.MSBuild/tools/msbuild/MSBuild.exe
   packages/build/FAKE/tools/FAKE.exe $@ --fsiargs -d:MONO build.fsx 
 else
   mono .paket/paket.exe restore
@@ -27,6 +27,8 @@ else
     fi
     exit $exit_code
   fi
+  # Note: the bundled MSBuild crashes hard on linux, so we still rely on the system-installed version
+  #export MSBuild=packages/build/RoslynTools.MSBuild/tools/msbuild/MSBuild.exe
   mono packages/build/FAKE/tools/FAKE.exe $@ --fsiargs -d:MONO build.fsx 
 fi
 

paket.dependencies

@@ -44,3 +44,11 @@ group Build
   nuget ILRepack
 
   github fsharp/FAKE modules/Octokit/Octokit.fsx
+
+  # Note: this package was produced using https://github.com/jaredpar/xcopy-msbuild and contains the two directories ".NETFramework\v4.5" and ".NETPortable\v4.5"
+  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

@@ -1,9 +1,12 @@
 <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>
   <ItemGroup>
     <PackageReference Include="SourceLink.Create.CommandLine" Version="2.1.1" PrivateAssets="all" />
     <PackageReference Include="SourceLink.Embed.PaketFiles" Version="2.1.1" PrivateAssets="all" />
   </ItemGroup>
-</Project>
+</Project>
+

src/Paket.Core/Paket.Core.fsproj

@@ -2199,4 +2199,4 @@
   </Choose>
   <Import Project="..\..\packages\NETStandard.Library\build\NETStandard.Library.targets" Condition="Exists('..\..\packages\NETStandard.Library\build\NETStandard.Library.targets')" Label="Paket" />
   <Import Project="..\..\packages\NETStandard.Library\build\$(__paket__NETStandard_Library_targets).targets" Condition="Exists('..\..\packages\NETStandard.Library\build\$(__paket__NETStandard_Library_targets).targets')" Label="Paket" />
-</Project>
+</Project>