Send "workload set not installed" messages

src/Cli/dotnet/commands/dotnet-workload/WorkloadCommandParser.cs

@@ -45,7 +45,10 @@ internal static string GetWorkloadsVersion(WorkloadInfoHelper workloadInfoHelper
         {
             workloadInfoHelper ??= new WorkloadInfoHelper(false);
 
-            return workloadInfoHelper.ManifestProvider.GetWorkloadVersion();
+            (string version, string error) = workloadInfoHelper.ManifestProvider.GetWorkloadVersion();
+
+            // The explicit space here is intentional, as it's easy to miss in localization and crucial for parsing
+            return version + (error is not null ? ' ' + Workloads.Workload.List.LocalizableStrings.WorkloadVersionNotInstalledShort : string.Empty);
         }
 
         internal static void ShowWorkloadsInfo(ParseResult parseResult = null, WorkloadInfoHelper workloadInfoHelper = null, IReporter reporter = null, string dotnetDir = null, bool showVersion = true)
@@ -56,9 +59,11 @@ internal static void ShowWorkloadsInfo(ParseResult parseResult = null, WorkloadI
             reporter ??= Utils.Reporter.Output;
             string dotnetPath = dotnetDir ?? Path.GetDirectoryName(Environment.ProcessPath);
 
+            string error = null;
             if (showVersion)
             {
-                reporter.WriteLine($" Workload version: {workloadInfoHelper.ManifestProvider.GetWorkloadVersion()}");
+                (string version, error) = workloadInfoHelper.ManifestProvider.GetWorkloadVersion();
+                reporter.WriteLine($" Workload version: {version}");
             }
 
             var useWorkloadSets = InstallStateContents.FromPath(Path.Combine(WorkloadInstallType.GetInstallStateFolder(workloadInfoHelper._currentSdkFeatureBand, workloadInfoHelper.UserLocalPath), "default.json")).UseWorkloadSets;
@@ -97,6 +102,11 @@ internal static void ShowWorkloadsInfo(ParseResult parseResult = null, WorkloadI
                 );
                 reporter.WriteLine("");
             }
+
+            if (error is not null)
+            {
+                reporter.WriteLine(error);
+            }
         }
 
         private static int ProcessArgs(ParseResult parseResult)

src/Cli/dotnet/commands/dotnet-workload/WorkloadHistoryRecorder.cs

@@ -54,15 +54,15 @@ public void Run(Action workloadAction)
         private WorkloadHistoryState GetWorkloadState()
         {
             var resolver = _workloadResolverFunc();
-            var currentWorkloadInfo = resolver.GetWorkloadVersion();
+            var currentWorkloadVersion = resolver.GetWorkloadVersion().version;
             return new WorkloadHistoryState()
             {
                 ManifestVersions = resolver.GetInstalledManifests().ToDictionary(manifest => manifest.Id.ToString(), manifest => $"{manifest.Version}/{manifest.ManifestFeatureBand}"),
                 InstalledWorkloads = _workloadInstaller.GetWorkloadInstallationRecordRepository()
                                                        .GetInstalledWorkloads(new SdkFeatureBand(_workloadResolver.GetSdkFeatureBand()))
                                                        .Select(id => id.ToString())
                                                        .ToList(),
-                WorkloadSetVersion = resolver.GetWorkloadVersion()
+                WorkloadSetVersion = currentWorkloadVersion
             };
 
         }

src/Cli/dotnet/commands/dotnet-workload/list/LocalizableStrings.resx

@@ -134,6 +134,9 @@
   <data name="WorkloadSetFromGlobalJsonInstalled" xml:space="preserve">
     <value>Found workload version {0} pinned in the global.json file at {1}.</value>
   </data>
+  <data name="WorkloadVersionNotInstalledShort" xml:space="preserve">
+    <value>(not installed)</value>
+  </data>
   <data name="WorkloadSetFromGlobalJsonNotInstalled" xml:space="preserve">
     <value>Found workload version {0} pinned in the global.json file at {1}, but it was not installed. Running `dotnet workload install`, `dotnet workload update`, or `dotnet workload restore` may fix this.</value>
   </data>

src/Cli/dotnet/commands/dotnet-workload/list/WorkloadListCommand.cs

@@ -93,7 +93,7 @@ public override int Execute()
                     }
                     else
                     {
-                        Reporter.WriteLine(string.Format(LocalizableStrings.WorkloadSetVersion, _workloadListHelper.WorkloadResolver.GetWorkloadVersion() ?? "unknown"));
+                        Reporter.WriteLine(string.Format(LocalizableStrings.WorkloadSetVersion, _workloadListHelper.WorkloadResolver.GetWorkloadVersion().version ?? "unknown"));
                     }
 
                     Reporter.WriteLine();

src/Resolvers/Microsoft.NET.Sdk.WorkloadManifestReader/IWorkloadManifestProvider.cs

@@ -14,7 +14,7 @@ public interface IWorkloadManifestProvider
 
         string GetSdkFeatureBand();
 
-        string? GetWorkloadVersion();
+        (string? version, string? error) GetWorkloadVersion();
 
         Dictionary<string, WorkloadSet> GetAvailableWorkloadSets();
     }

src/Resolvers/Microsoft.NET.Sdk.WorkloadManifestReader/IWorkloadResolver.cs

@@ -20,7 +20,7 @@ public interface IWorkloadResolver
         string GetManifestFeatureBand(string manifestId);
         IEnumerable<WorkloadManifestInfo> GetInstalledManifests();
         string GetSdkFeatureBand();
-        string? GetWorkloadVersion();
+        (string? version, string? error) GetWorkloadVersion();
         IEnumerable<WorkloadId> GetUpdatedWorkloads(WorkloadResolver advertisingManifestResolver, IEnumerable<WorkloadId> installedWorkloads);
         WorkloadManifest GetManifestFromWorkload(WorkloadId workloadId);
 

src/Resolvers/Microsoft.NET.Sdk.WorkloadManifestReader/SdkDirectoryWorkloadManifestProvider.cs

@@ -243,20 +243,29 @@ void ThrowExceptionIfManifestsNotAvailable()
             }
         }
 
-        public string? GetWorkloadVersion()
+        public (string? version, string? error) GetWorkloadVersion()
         {
             if (_globalJsonWorkloadSetVersion != null)
             {
-                return _globalJsonWorkloadSetVersion;
+                // _exceptionToThrow is set to null here if and only if the workload set is not installed.
+                // If this came from --info or workload --version, the error won't be thrown, but we should still
+                // suggest running `dotnet workload restore` to the user.
+                return (_globalJsonWorkloadSetVersion, _exceptionToThrow?.Message);
             }
 
             ThrowExceptionIfManifestsNotAvailable();
 
             if (_workloadSet?.Version is not null)
             {
-                return _workloadSet?.Version!;
+                return (_workloadSet.Version, null);
             }
 
+            var installStateFilePath = Path.Combine(WorkloadInstallType.GetInstallStateFolder(_sdkVersionBand, _sdkOrUserLocalPath), "default.json");
+            var installState = InstallStateContents.FromPath(installStateFilePath)!;
+            string? shouldRestoreMessage = installState.UseWorkloadSets == true ?
+                Strings.ShouldInstallAWorkloadSet :
+                null;
+
             using (SHA256 sha256Hash = SHA256.Create())
             {
                 byte[] bytes = sha256Hash.ComputeHash(Encoding.UTF8.GetBytes(string.Join(";",
@@ -271,7 +280,7 @@ void ThrowExceptionIfManifestsNotAvailable()
                     sb.Append(bytes[b].ToString("x2"));
                 }
 
-                return $"{_sdkVersionBand.ToStringWithoutPrerelease()}-manifests.{sb}";
+                return ($"{_sdkVersionBand.ToStringWithoutPrerelease()}-manifests.{sb}", shouldRestoreMessage);
             }
         }
 

src/Resolvers/Microsoft.NET.Sdk.WorkloadManifestReader/Strings.resx

@@ -201,6 +201,9 @@
     <value>Workload version {0}, which was specified in {1}, was not found. Run "dotnet workload restore" to install this workload version.</value>
     <comment>{Locked="dotnet workload restore"}</comment>
   </data>
+  <data name="ShouldInstallAWorkloadSet" xml:space="preserve">
+    <value>Workloads are configured to install and update using workload versions, but none were found. Run "dotnet workload restore" to install a workload version.</value>
+  </data>
   <data name="WorkloadVersionNotFound" xml:space="preserve">
     <value>Workload version {0} was not found.</value>
   </data>

src/Resolvers/Microsoft.NET.Sdk.WorkloadManifestReader/TempDirectoryWorkloadManifestProvider.cs

@@ -53,7 +53,7 @@ public IEnumerable<string> GetManifestDirectories()
         }
 
         public string GetSdkFeatureBand() => _sdkVersionBand;
-        public string? GetWorkloadVersion() => _sdkVersionBand.ToString() + ".2";
+        public (string? version, string? error) GetWorkloadVersion() => (_sdkVersionBand.ToString() + ".2", null);
         public Dictionary<string, WorkloadSet> GetAvailableWorkloadSets() => new();
     }
 }

src/Resolvers/Microsoft.NET.Sdk.WorkloadManifestReader/WorkloadResolver.cs

@@ -115,7 +115,7 @@ public void RefreshWorkloadManifests()
             InitializeManifests();
         }
 
-        public string? GetWorkloadVersion() => _manifestProvider.GetWorkloadVersion();
+        public (string? version, string? error) GetWorkloadVersion() => _manifestProvider.GetWorkloadVersion();
 
         private void LoadManifestsFromProvider(IWorkloadManifestProvider manifestProvider)
         {
@@ -778,7 +778,7 @@ public void RefreshWorkloadManifests() { }
             public Dictionary<string, WorkloadSet> GetAvailableWorkloadSets() => new();
             public IEnumerable<ReadableWorkloadManifest> GetManifests() => Enumerable.Empty<ReadableWorkloadManifest>();
             public string GetSdkFeatureBand() => _sdkFeatureBand;
-            public string? GetWorkloadVersion() => _sdkFeatureBand.ToString() + ".2";
+            public (string? version, string? error) GetWorkloadVersion() => (_sdkFeatureBand + ".2", null);
         }
     }