Merge pull request #34914 Update upgrade fixer

Don’t suggest upgrading to an unsupported state

src/EditorFeatures/CSharpTest/Diagnostics/UpgradeProject/UpgradeProjectTests.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CodeFixes;
 using Microsoft.CodeAnalysis.CSharp;
@@ -46,10 +47,27 @@ internal override (DiagnosticAnalyzer, CodeFixProvider) CreateDiagnosticProvider
             await TestAsync(initialMarkup, initialMarkup, parseOptions); // no change to markup
         }
 
+        private async Task TestLanguageVersionNotUpgradedAsync(string initialMarkup,
+#pragma warning disable IDE0060 // Remove unused parameter
+            LanguageVersion expected,
+#pragma warning restore IDE0060 // Remove unused parameter
+            ParseOptions parseOptions,
+            int index = 0)
+        {
+            var parameters = new TestParameters(parseOptions: parseOptions, index: index);
+            using (var workspace = CreateWorkspaceFromOptions(initialMarkup, parameters))
+            {
+                var (actions, actionsToInvoke) = await GetCodeActionsAsync(workspace, parameters);
+
+                Assert.Empty(actions);
+                Assert.Null(actionsToInvoke);
+            }
+        }
+
         [Fact]
         public async Task UpgradeProjectFromCSharp7_2ToCSharp8()
         {
-            await TestLanguageVersionUpgradedAsync(
+            await TestLanguageVersionNotUpgradedAsync(
 @"class C
 {
     object F = [|null!|];
@@ -61,7 +79,7 @@ public async Task UpgradeProjectFromCSharp7_2ToCSharp8()
         [Fact]
         public async Task UpgradeProjectFromCSharp7ToCSharp8()
         {
-            await TestLanguageVersionUpgradedAsync(
+            await TestLanguageVersionNotUpgradedAsync(
 @"class C
 {
     object F = [|null!|];
@@ -321,7 +339,7 @@ class Program
         [Fact]
         public async Task UpgradeProjectForVerbatimInterpolatedString()
         {
-            await TestLanguageVersionUpgradedAsync(
+            await TestLanguageVersionNotUpgradedAsync(
 @"
 class Program
 {
@@ -366,7 +384,7 @@ void A()
         [Fact]
         public async Task UpgradeAllProjectsToCSharp8()
         {
-            await TestLanguageVersionUpgradedAsync(
+            await TestLanguageVersionNotUpgradedAsync(
 @"<Workspace>
     <Project Language=""C#"" LanguageVersion=""6"">
         <Document>
@@ -471,10 +489,8 @@ void A()
     <Project Language=""C#"" LanguageVersion=""800"">
     </Project>
 </Workspace>",
-                new[] {
-                    string.Format(CSharpFeaturesResources.Upgrade_this_project_to_csharp_language_version_0, versionPreview),
-                    string.Format(CSharpFeaturesResources.Upgrade_all_csharp_projects_to_language_version_0, versionPreview)
-    });
+                new string[0]
+    );
         }
 
         [Fact]
@@ -578,10 +594,7 @@ class C
     <Project Language=""Visual Basic"">
     </Project>
 </Workspace>",
-                new[] {
-                    string.Format(CSharpFeaturesResources.Upgrade_this_project_to_csharp_language_version_0, previewVersion),
-                    string.Format(CSharpFeaturesResources.Upgrade_all_csharp_projects_to_language_version_0, previewVersion)
-                    });
+                new string[0]);
         }
 
         [Fact]
@@ -737,7 +750,7 @@ public void N()
         [Fact]
         public async Task UpgradeProjectForDefaultInterfaceImplementation_CS8703()
         {
-            await TestLanguageVersionUpgradedAsync(
+            await TestLanguageVersionNotUpgradedAsync(
 @"
 public interface I1
 {
@@ -751,7 +764,7 @@ public interface I1
         [Fact]
         public async Task UpgradeProjectForDefaultInterfaceImplementation_CS8706()
         {
-            await TestLanguageVersionUpgradedAsync(
+            await TestLanguageVersionNotUpgradedAsync(
 @"
 <Workspace>
     <Project Language=""C#"" AssemblyName=""Assembly1"" CommonReferences=""true"">
@@ -780,7 +793,7 @@ void M1()
         [Fact]
         public async Task UpgradeProjectWithOpenTypeMatchingConstantPattern_01()
         {
-            await TestLanguageVersionUpgradedAsync(
+            await TestLanguageVersionNotUpgradedAsync(
 @"
 class Test
 {
@@ -793,7 +806,7 @@ class Test
         [Fact]
         public async Task UpgradeProjectWithOpenTypeMatchingConstantPattern_02()
         {
-            await TestLanguageVersionUpgradedAsync(
+            await TestLanguageVersionNotUpgradedAsync(
 @"
 class Test
 {
@@ -806,7 +819,7 @@ class Test
         [Fact]
         public async Task UpgradeProjectWithOpenTypeMatchingConstantPattern_03()
         {
-            await TestLanguageVersionUpgradedAsync(
+            await TestLanguageVersionNotUpgradedAsync(
 @"
 class Test
 {

src/Features/CSharp/Portable/UpgradeProject/CSharpUpgradeProjectCodeFixProvider.cs

@@ -85,8 +85,11 @@ public override bool IsUpgrade(ParseOptions projectOptions, string newVersion)
             var parseOptions = (CSharpParseOptions)projectOptions;
             Contract.ThrowIfFalse(LanguageVersionFacts.TryParse(newVersion, out var parsedNewVersion));
 
+            var mappedVersion = parsedNewVersion.MapSpecifiedToEffectiveVersion();
+
             // treat equivalent versions (one generic and one specific) to be a valid upgrade
-            return parsedNewVersion.MapSpecifiedToEffectiveVersion() >= parseOptions.LanguageVersion &&
+            return mappedVersion >= parseOptions.LanguageVersion &&
+                mappedVersion < LanguageVersion.CSharp8 &&
                 parseOptions.SpecifiedLanguageVersion.ToDisplayString() != newVersion;
         }
     }

src/Features/Core/Portable/UpgradeProject/AbstractUpgradeProjectCodeFixProvider.cs

@@ -39,15 +39,24 @@ protected ImmutableArray<CodeAction> GetUpgradeProjectCodeActionsAsync(CodeFixCo
             var project = context.Document.Project;
             var solution = project.Solution;
             var newVersion = SuggestedVersion(context.Diagnostics);
+
             var result = new List<CodeAction>();
             var language = project.Language;
 
+            var upgradeableProjects = solution.Projects.Where(p => CanUpgrade(p, language, newVersion)).AsImmutable();
+
+            if (upgradeableProjects.Length == 0)
+            {
+                return ImmutableArray<CodeAction>.Empty;
+            }
+
             var fixOneProjectTitle = string.Format(UpgradeThisProjectResource, newVersion);
             var fixOneProject = new ProjectOptionsChangeAction(fixOneProjectTitle,
                 _ => Task.FromResult(UpgradeProject(project, newVersion)));
 
             result.Add(fixOneProject);
-            if (solution.Projects.Count(p => CanUpgrade(p, language, newVersion)) > 1)
+
+            if (upgradeableProjects.Length > 1)
             {
                 var fixAllProjectsTitle = string.Format(UpgradeAllProjectsResource, newVersion);