[DotNetCore] Allow re-targetting to any of the supported frameworks

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/973338

2 files changed, 54 insertions, 18 deletions

diff --git a/main/src/addins/MonoDevelop.DotNetCore/MonoDevelop.DotNetCore.Gui/DotNetCoreRuntimeOptionsPanelWidget.cs b/main/src/addins/MonoDevelop.DotNetCore/MonoDevelop.DotNetCore.Gui/DotNetCoreRuntimeOptionsPanelWidget.cs
index 25915b90f6..11dcf4ce29 100644
--- a/main/src/addins/MonoDevelop.DotNetCore/MonoDevelop.DotNetCore.Gui/DotNetCoreRuntimeOptionsPanelWidget.cs
+++ b/main/src/addins/MonoDevelop.DotNetCore/MonoDevelop.DotNetCore.Gui/DotNetCoreRuntimeOptionsPanelWidget.cs
@@ -35,7 +35,7 @@ namespace MonoDevelop.DotNetCore.Gui
 {
 	partial class DotNetCoreRuntimeOptionsPanelWidget
 	{
-		readonly List<TargetFramework> frameworks;
+		readonly List<TargetFramework> installedFrameworks;
 		readonly DotNetProject project;
 		readonly DotNetCoreProjectExtension dotNetCoreProject;
 
@@ -56,36 +56,38 @@ namespace MonoDevelop.DotNetCore.Gui
 			} else {
 				dotNetCoreProject = project.GetFlavor<DotNetCoreProjectExtension> ();
 				var supportedTargetFrameworks = new DotNetCoreProjectSupportedTargetFrameworks (project);
-				frameworks = supportedTargetFrameworks.GetFrameworks ().ToList ();
+				installedFrameworks = supportedTargetFrameworks.GetFrameworks ().ToList ();
+				var knownFrameworks = supportedTargetFrameworks.GetKnownFrameworks ()
+					.Concat (installedFrameworks)
+					.Distinct ()
+					.ToList ();
 
-				bool notInstalled = false;
-				if (!frameworks.Any (fx => fx.Id == project.TargetFramework.Id)) {
-					frameworks.Add (project.TargetFramework);
-					notInstalled = true;
+				if (!knownFrameworks.Any (fx => fx.Id == project.TargetFramework.Id)) {
+					knownFrameworks.Add (project.TargetFramework);
 				}
 
 				//sort by id ascending, version descending
-				frameworks.Sort ((x, y) => {
+				knownFrameworks.Sort ((x, y) => {
 					var cmp = string.CompareOrdinal (x.Id.Identifier, y.Id.Identifier);
 					if (cmp != 0)
 						return cmp;
 					return string.CompareOrdinal (y.Id.Version, x.Id.Version);
 				});
 
-				for (int i = 0; i < frameworks.Count; i++) {
-					var fx = frameworks[i];
+				for (int i = 0; i < knownFrameworks.Count; i++) {
+					var fx = knownFrameworks[i];
+					if (installedFrameworks.Any (f => f.Id == fx.Id)) {
+						runtimeVersionCombo.AppendText (fx.GetDisplayName ());
+					} else {
+						runtimeVersionCombo.AppendText (GettextCatalog.GetString ("{0} (Not installed)", fx.GetDisplayName ()));
+					}
+
 					if (project.TargetFramework.Id == fx.Id) {
-						if (notInstalled)
-							runtimeVersionCombo.AppendText (GettextCatalog.GetString ("{0} (Not installed)", fx.GetDisplayName ()));
-						else
-							runtimeVersionCombo.AppendText (fx.GetDisplayName ());
 						runtimeVersionCombo.Active = i;
-					} else {
-						runtimeVersionCombo.AppendText (fx.GetDisplayName ());
 					}
 				}
 
-				Sensitive = frameworks.Count > 1;
+				Sensitive = knownFrameworks.Count > 1;
 			}
 		}
 
@@ -94,10 +96,10 @@ namespace MonoDevelop.DotNetCore.Gui
 			if (project == null || runtimeVersionCombo.Active == -1 || project.HasMultipleTargetFrameworks)
 				return;
 
-			TargetFramework framework = frameworks [runtimeVersionCombo.Active];
+			TargetFramework framework = installedFrameworks [runtimeVersionCombo.Active];
 
 			if (framework != project.TargetFramework) {
-				project.TargetFramework = frameworks [runtimeVersionCombo.Active];
+				project.TargetFramework = installedFrameworks [runtimeVersionCombo.Active];
 			}
 		}
 	}
diff --git a/main/src/addins/MonoDevelop.DotNetCore/MonoDevelop.DotNetCore/DotNetCoreProjectSupportedTargetFrameworks.cs b/main/src/addins/MonoDevelop.DotNetCore/MonoDevelop.DotNetCore/DotNetCoreProjectSupportedTargetFrameworks.cs
index 468cfd1aa8..261c1b103b 100644
--- a/main/src/addins/MonoDevelop.DotNetCore/MonoDevelop.DotNetCore/DotNetCoreProjectSupportedTargetFrameworks.cs
+++ b/main/src/addins/MonoDevelop.DotNetCore/MonoDevelop.DotNetCore/DotNetCoreProjectSupportedTargetFrameworks.cs
@@ -60,6 +60,40 @@ namespace MonoDevelop.DotNetCore
 			return new TargetFramework [0];
 		}
 
+		static string [] supportedNetStandardVersions = new string [] {
+			"2.1", "2.0", "1.6", "1.5", "1.4", "1.3", "1.2", "1.1"
+		};
+		static string [] supportedNetCoreAppVersions = new string [] {
+			"3.1", "3.0", "2.2", "2.1"
+		};
+
+		public IEnumerable<TargetFramework> GetKnownFrameworks ()
+		{
+			static IEnumerable<TargetFramework> GetKnownNetStandardFrameworks ()
+			{
+				foreach (var v in supportedNetStandardVersions) {
+					yield return CreateTargetFramework (".NETStandard", v);
+				}
+			}
+
+			static IEnumerable<TargetFramework> GetKnownNetCoreAppFrameworks ()
+			{
+				foreach (var v in supportedNetCoreAppVersions) {
+					yield return CreateTargetFramework (".NETCoreApp", v);
+				}
+			}
+
+			if (framework.IsNetStandard ()) {
+				return GetKnownNetStandardFrameworks ();
+			} else if (framework.IsNetCoreApp ()) {
+				return GetKnownNetCoreAppFrameworks ();
+			} else if (framework.IsNetFramework ()) {
+				return GetNetFrameworkTargetFrameworks ();
+			}
+
+			return new TargetFramework [0];
+		}
+
 		public static IEnumerable<TargetFramework> GetNetStandardTargetFrameworks ()
 		{
 			if (DotNetCoreRuntime.IsNetCore30Installed () || MonoRuntimeInfoExtensions.CurrentRuntimeVersion.SupportsNetStandard21 ())