enable support for .NET Fx 4.6.1 <-> .NET Standard 2

integrationtests/Paket.IntegrationTests/InstallSpecs.fs

@@ -450,6 +450,15 @@ let ``#3062 install should use external lock file``() =
     newLockFile.Groups.[GroupName "main"].Resolution.ContainsKey (PackageName "FAKE") |> shouldEqual true
     newLockFile.Groups.[GroupName "main"].Resolution.[PackageName "Machine.Specifications"].Version |> shouldEqual (SemVer.Parse "0.12")
 
+[<Test>]
+let ``#3447 netfx461 should support netstandard20 if the appconfig flag is set``() =
+    let newLockFile = installWithNfx461compat "i003447-netfx461-ns20"
+    // the dependencies file contains a restriction "framework: net461". So without the flag, the lock file contains only the one package because the dependencies for ns20 have been ignored.
+    // If the flag works correctly, then the lock file should contain all the microsoft asp.net core packages.
+    // The strategy is min, so the resolution should be stable regarding the versions.
+    newLockFile.Groups.[GroupName "main"].Resolution.ContainsKey (PackageName "Microsoft.AspNetCore.Server.Kestrel.Core") |> shouldEqual true
+    newLockFile.Groups.[GroupName "main"].Resolution.[PackageName "Microsoft.AspNetCore.Server.Kestrel.Core"].Version |> shouldEqual (SemVer.Parse "2.1.2")
+
 
 #if INTERACTIVE
 ;;

integrationtests/Paket.IntegrationTests/TestHelper.fs

@@ -214,8 +214,18 @@ let installEx checkZeroWarn scenario =
     #endif
     LockFile.LoadFrom(Path.Combine(scenarioTempPath scenario,"paket.lock"))
 
+let installExWithNfx461compat checkZeroWarn scenario =
+    #if INTERACTIVE
+    paket "install --verbose" scenario |> printfn "%s"
+    #else
+    paketEx checkZeroWarn  "--enablenetfx461netstandard2support install" scenario |> ignore
+    #endif
+    LockFile.LoadFrom(Path.Combine(scenarioTempPath scenario,"paket.lock"))
+
 let install scenario = installEx false scenario
 
+let installWithNfx461compat scenario = installExWithNfx461compat false scenario
+
 let restore scenario = paketEx false "restore" scenario |> ignore
 
 let updateShouldFindPackageConflict packageName scenario =

integrationtests/scenarios/i003447-netfx461-ns20/before/paket.dependencies

@@ -0,0 +1,5 @@
+source https://api.nuget.org/v3/index.json
+storage: none
+framework: net461
+
+nuget Microsoft.AspNetCore 2.1.2 strategy:min

src/Paket.Bootstrapper/ArgumentParser.cs

@@ -32,6 +32,7 @@ public static class CommandArgs
         }
         public static class AppSettingKeys
         {
+            public const string EnableNetFx461NetStandard2Support = "EnableNetFx461NetStandard2Support";
             public const string PreferNuget = "PreferNuget";
             public const string ForceNuget = "ForceNuget";
             public const string NugetSource = "NugetSource";
@@ -115,7 +116,7 @@ public static BootstrapperOptions ParseArgumentsAndConfigurations(IEnumerable<st
 
                 // Assume --run and that all arguments are for the real paket binary
                 options.Run = true;
-                options.RunArgs = new List<string>(commandArgs);
+                options.RunArgs.AddRange(new List<string>(commandArgs));
                 commandArgs.Clear();
 
                 // Don't check more than twice a day
@@ -205,6 +206,10 @@ private static NameValueCollection ReadSettings(string configFilePath)
 
         private static void FillOptionsFromAppSettings(BootstrapperOptions options, NameValueCollection appSettings)
         {
+            if (appSettings.IsTrue(AppSettingKeys.EnableNetFx461NetStandard2Support))
+            {
+                options.RunArgs.Add("--enablenetfx461netstandard2support");
+            }
             if (appSettings.IsTrue(AppSettingKeys.PreferNuget))
             {
                 options.PreferNuget = true;
@@ -249,7 +254,7 @@ private static void FillRunOptionsFromArguments(BootstrapperOptions options, Lis
             if (runIndex != -1)
             {
                 options.Run = true;
-                options.RunArgs = commandArgs.GetRange(runIndex + 1, commandArgs.Count - runIndex - 1);
+                options.RunArgs.AddRange(commandArgs.GetRange(runIndex + 1, commandArgs.Count - runIndex - 1));
                 commandArgs.RemoveRange(runIndex, commandArgs.Count - runIndex);
             }
         }

src/Paket.Bootstrapper/BootstrapperOptions.cs

@@ -9,18 +9,18 @@ public BootstrapperOptions()
         {
             Verbosity = Verbosity.Normal;
             DownloadArguments = new DownloadArguments();
-            RunArgs = Enumerable.Empty<string>();
+            RunArgs = new List<string>();
             UnprocessedCommandArgs = Enumerable.Empty<string>();
         }
 
         public DownloadArguments DownloadArguments { get; set; }
-
+        
         public Verbosity Verbosity { get; set; }
         public bool ForceNuget { get; set; }
         public bool PreferNuget { get; set; }
         public bool ShowHelp { get; set; }
         public bool Run { get; set; }
-        public IEnumerable<string> RunArgs { get; set; }
+        public List<string> RunArgs { get; set; }
         public IEnumerable<string> UnprocessedCommandArgs { get; set; }
     }
 }

src/Paket.Core/Versioning/FrameworkHandling.fs

@@ -6,6 +6,26 @@ open System.Diagnostics
 open Logging
 
 
+/// how to handle compatibility between .NET-FX <-> .NET
+[<RequireQualifiedAccess>]
+type ToolingSupportMode =
+
+/// only support framework mappings which are in-box.
+/// This means .NET Standard 2 is only supported from 4.7.1 onwards.
+| NativeSupport
+
+/// support .NET Standard 2 from .NET Framework 4.6.1 onwards.
+/// This requires a supported SDK during compilation, otherwise you may get successfull compilations, but errors at runtime. Use at your own risk.
+| ToolingSupportNetSDK2
+
+
+module DotnetToolingSupport =
+    /// Change how paket handles the .NET-FX <-> .NET Standard compatibility tables.
+    /// Changing this flag influences resolution and lockfile generation.
+    /// You should only ever change it in MAIN then not touch it at runtime.
+    let mutable mode = ToolingSupportMode.NativeSupport
+
+
 /// The .NET Standard version.
 // Each time a new version is added NuGetPackageCache.CurrentCacheVersion should be bumped.
 [<RequireQualifiedAccess>]
@@ -621,7 +641,11 @@ type FrameworkIdentifier =
         | DotNetFramework FrameworkVersion.V4_5_2 -> [ DotNetFramework FrameworkVersion.V4_5_1; DotNetStandard DotNetStandardVersion.V1_2 ]
         | DotNetFramework FrameworkVersion.V4_5_3 -> [ DotNetFramework FrameworkVersion.V4_5_2; DotNetStandard DotNetStandardVersion.V1_2 ]
         | DotNetFramework FrameworkVersion.V4_6 -> [ DotNetFramework FrameworkVersion.V4_5_3; DotNetStandard DotNetStandardVersion.V1_3 ]
-        | DotNetFramework FrameworkVersion.V4_6_1 -> [ DotNetFramework FrameworkVersion.V4_6; DotNetStandard DotNetStandardVersion.V1_4 ]
+        | DotNetFramework FrameworkVersion.V4_6_1 ->
+            match DotnetToolingSupport.mode with
+            | ToolingSupportMode.NativeSupport -> [ DotNetFramework FrameworkVersion.V4_6; DotNetStandard DotNetStandardVersion.V1_4 ]
+            // .NET Standard 2.0 will propagate "down", so we don't need any switches on the subsequent frameworks
+            | ToolingSupportMode.ToolingSupportNetSDK2 -> [ DotNetFramework FrameworkVersion.V4_6; DotNetStandard DotNetStandardVersion.V2_0 ]
         | DotNetFramework FrameworkVersion.V4_6_2 -> [ DotNetFramework FrameworkVersion.V4_6_1; DotNetStandard DotNetStandardVersion.V1_5 ]
         | DotNetFramework FrameworkVersion.V4_6_3 -> [ DotNetFramework FrameworkVersion.V4_6_2 ]
         | DotNetFramework FrameworkVersion.V4_7 -> [ DotNetFramework FrameworkVersion.V4_6_3]

src/Paket/Commands.fs

@@ -665,6 +665,7 @@ type Command =
     | [<AltCommandLine("-v");Inherit>]                  Verbose
     | [<Inherit>]                                       Log_File of path:string
     | [<Hidden;Inherit>]                                From_Bootstrapper
+    | [<Hidden;Inherit;Unique;CustomCommandLine("--enablenetfx461netstandard2support")>] EnableNetFx461NetStandard2Support
     // subcommands
     | [<CustomCommandLine("add")>]                      Add of ParseResults<AddArgs>
     | [<CustomCommandLine("github")>]                   Github of ParseResults<GithubArgs>
@@ -733,6 +734,7 @@ with
             | Verbose -> "print detailed information to the console"
             | Version -> "show Paket version"
             | From_Bootstrapper -> "call coming from the '--run' feature of the bootstrapper"
+            | EnableNetFx461NetStandard2Support -> "enable mapping when called from the bootstrapper. do not use manually."
 
 let commandParser = ArgumentParser.Create<Command>(programName = "paket", errorHandler = new ProcessExiter(), checkStructure = false)
 

src/Paket/Paket.fsproj

@@ -79,6 +79,7 @@
     <Reference Include="Microsoft.Build.Utilities.v4.0" />
     <Reference Include="mscorlib" />
     <Reference Include="System" />
+    <Reference Include="System.Configuration" />
     <Reference Include="System.Core" />
     <Reference Include="System.Data" />
     <Reference Include="System.Data.Linq" />

src/Paket/Program.fs

@@ -13,6 +13,16 @@ open PackageSources
 
 let sw = Stopwatch.StartNew()
 
+type System.Collections.Specialized.NameValueCollection with
+    member this.GetKey(key:string) =
+        if this <> null && this.AllKeys |> Array.contains key then
+            this.Get(key)
+        else
+            null
+    member this.IsTrue(key:string) =
+        let v = this.GetKey(key)
+        String.equalsIgnoreCase v "true"
+
 type PaketExiter() =
     interface IExiter with
         member __.Name = "paket exiter"
@@ -863,6 +873,7 @@ let handleCommand silent command =
     | Verbose
     | Silent
     | From_Bootstrapper
+    | EnableNetFx461NetStandard2Support
     | Version
     | Log_File _ -> failwithf "internal error: this code should never be reached."
 
@@ -879,14 +890,20 @@ let main() =
 
     try
     let args = Environment.GetCommandLineArgs()
+    let appSettings = System.Configuration.ConfigurationManager.AppSettings
+    if appSettings.IsTrue("EnableNetFx461NetStandard2Support") ||
+       args |> Array.contains "--enablenetfx461netstandard2support" then
+        DotnetToolingSupport.mode <- ToolingSupportMode.ToolingSupportNetSDK2
     match args with
+    | [| _; "restore" |] | [| _; "--from-bootstrapper"; "--enablenetfx461netstandard2support"; "restore" |]
     | [| _; "restore" |] | [| _; "--from-bootstrapper"; "restore" |] ->
         // Global restore fast route, see https://github.com/fsprojects/Argu/issues/90
         processWithValidationEx
             ignore
             false
             (fun _ -> true)
             (fun _ -> Dependencies.Locate().Restore()) ()
+    | [| _; "restore"; "--project"; project |] | [| _; "--from-bootstrapper"; "--enablenetfx461netstandard2support"; "restore"; "--project"; project |]
     | [| _; "restore"; "--project"; project |] | [| _; "--from-bootstrapper"; "restore"; "--project"; project |] ->
         // Project restore fast route, see https://github.com/fsprojects/Argu/issues/90
         processWithValidationEx
@@ -902,6 +919,7 @@ let main() =
             false
             (fun _ -> true)
             (fun _ -> Dependencies.Locate().Restore(false, None, project, false, false, false, Some targetFramework, Some outputPath)) ()
+    | [| _; "install" |] | [| _; "--from-bootstrapper"; "--enablenetfx461netstandard2support"; "install" |]
     | [| _; "install" |] | [| _; "--from-bootstrapper"; "install" |] ->
         // Global restore fast route, see https://github.com/fsprojects/Argu/issues/90
         processWithValidationEx