Add LanguageVersion for C# 14 (#79725)

Author: Julien Couvreur

docs/Language Feature Status.md

@@ -11,17 +11,7 @@ efforts behind them.
 | Feature | Branch | State | Developer | Reviewer | IDE Buddy | LDM Champ |
 | ------- | ------ | ----- | --------- | -------- | --------- | --------- |
 | Runtime Async | [runtime-async](https://github.com/dotnet/roslyn/tree/features/runtime-async) | [In Progress](https://github.com/dotnet/roslyn/issues/75960) | [333fred](https://github.com/333fred) | [jcouv](https://github.com/jcouv), [RikkiGibson](https://github.com/RikkiGibson) |  |  |
-| [`field` keyword in properties](https://github.com/dotnet/csharplang/issues/140) | [field-keyword](https://github.com/dotnet/roslyn/tree/features/field-keyword) | [Merged into 17.12p3](https://github.com/dotnet/roslyn/issues/57012) | [Youssef1313](https://github.com/Youssef1313), [cston](https://github.com/cston) | [333fred](https://github.com/333fred), [RikkiGibson](https://github.com/RikkiGibson) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) |
-| [First-class Span Types](https://github.com/dotnet/csharplang/issues/7905) | [FirstClassSpan](https://github.com/dotnet/roslyn/tree/features/FirstClassSpan) | [Merged into 17.13p1](https://github.com/dotnet/roslyn/issues/73445) | [jjonescz](https://github.com/jjonescz) | [cston](https://github.com/cston), [333fred](https://github.com/333fred) | | [333fred](https://github.com/333fred), [stephentoub](https://github.com/stephentoub) |
-| [Unbound generic types in `nameof`](https://github.com/dotnet/csharplang/issues/8480) | [PR](https://github.com/dotnet/roslyn/pull/75368) | [Merged into 17.13p2](https://github.com/dotnet/roslyn/pull/75368) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [jcouv](https://github.com/jcouv), [AlekseyTs](https://github.com/AlekseyTs) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) |
-| [String literals in data section as UTF8](https://github.com/dotnet/roslyn/blob/main/docs/features/string-literals-data-section.md) | [PR](https://github.com/dotnet/roslyn/pull/76036) | [Merged into 17.13p4](https://github.com/dotnet/roslyn/issues/76234) | [jjonescz](https://github.com/jjonescz) | [AlekseyTs](https://github.com/AlekseyTs), [cston](https://github.com/cston) | N/A | N/A |
-| [Simple lambda parameters with modifiers](https://github.com/dotnet/csharplang/blob/main/proposals/simple-lambda-parameters-with-modifiers.md) | [PR](https://github.com/dotnet/roslyn/pull/75400) | [Merged into 17.14p1](https://github.com/dotnet/roslyn/pull/75400) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [jjonescz](https://github.com/jjonescz), [cston](https://github.com/cston) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) |
-| [Partial Events and Constructors](https://github.com/dotnet/csharplang/issues/9058) | [PartialEventsCtors](https://github.com/dotnet/roslyn/tree/features/PartialEventsCtors) | [Merged into 17.14p3](https://github.com/dotnet/roslyn/issues/76859) | [jjonescz](https://github.com/jjonescz) | [cston](https://github.com/cston), [RikkiGibson](https://github.com/RikkiGibson) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [jaredpar](https://github.com/jaredpar) |
-| [Extensions](https://github.com/dotnet/csharplang/issues/8697) | [extensions](https://github.com/dotnet/roslyn/tree/features/extensions) | [Preview merged into 17.14p3](https://github.com/dotnet/roslyn/issues/76130) | [jcouv](https://github.com/jcouv), [AlekseyTs](https://github.com/AlekseyTs) | [jjonescz](https://github.com/jjonescz), TBD | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [MadsTorgersen](https://github.com/MadsTorgersen) |
-| [Null-conditional assignment](https://github.com/dotnet/csharplang/issues/6045) | [null-conditional-assignment](https://github.com/dotnet/roslyn/tree/features/null-conditional-assignment) | [Merged into 17.14p3](https://github.com/dotnet/roslyn/issues/75554) | [RikkiGibson](https://github.com/RikkiGibson) | [cston](https://github.com/cston), [jjonescz](https://github.com/jjonescz) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [RikkiGibson](https://github.com/RikkiGibson) |
-| [Ignored directives](https://github.com/dotnet/csharplang/issues/8617) | [PR](https://github.com/dotnet/roslyn/pull/77696) | Merged into 17.14p3 | [jjonescz](https://github.com/jjonescz) | [RikkiGibson](https://github.com/RikkiGibson), [jaredpar](https://github.com/jaredpar) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [jaredpar](https://github.com/jaredpar) |
 | [Dictionary expressions](https://github.com/dotnet/csharplang/issues/8659) | [dictionary-expressions](https://github.com/dotnet/roslyn/tree/features/dictionary-expressions) | [In progress](https://github.com/dotnet/roslyn/issues/76310) | [cston](https://github.com/cston), [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [333fred](https://github.com/333fred), [jcouv](https://github.com/jcouv) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) |
-| [User Defined Compound Assignment Operators](https://github.com/dotnet/csharplang/issues/9101) | [UserDefinedCompoundAssignment](https://github.com/dotnet/roslyn/tree/features/UserDefinedCompoundAssignment) | [Merged to main](https://github.com/dotnet/roslyn/issues/76934) | [AlekseyTs](https://github.com/AlekseyTs) | [333fred](https://github.com/333fred), [cston](https://github.com/cston) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [AlekseyTs](https://github.com/AlekseyTs) |
 
 # Working Set VB
 
@@ -30,6 +20,21 @@ efforts behind them.
 | Recognizing 'unmanaged' constraint | main | [Merged into 17.13 P2](https://github.com/dotnet/roslyn/pull/75665) | [AlekseyTs](https://github.com/AlekseyTs) | [cston](https://github.com/cston), [333fred](https://github.com/333fred) | (no IDE impact) | [jaredpar](https://github.com/jaredpar) |
 | Overload Resolution Priority | main | [Merged into 17.13 P3](https://github.com/dotnet/roslyn/pull/76419) | [AlekseyTs](https://github.com/AlekseyTs) | [333fred](https://github.com/333fred), [cston](https://github.com/cston) | (no IDE impact) | [333fred](https://github.com/333fred) |
 
+# C# 14.0
+
+| Feature | Branch | State | Developer | Reviewer | IDE Buddy | LDM Champ |
+| ------- | ------ | ----- | --------- | -------- | --------- | --------- |
+| [`field` keyword in properties](https://github.com/dotnet/csharplang/issues/8635) | [field-keyword](https://github.com/dotnet/roslyn/tree/features/field-keyword) | [Merged into 17.12p3](https://github.com/dotnet/roslyn/issues/57012) | [Youssef1313](https://github.com/Youssef1313), [cston](https://github.com/cston) | [333fred](https://github.com/333fred), [RikkiGibson](https://github.com/RikkiGibson) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) |
+| [First-class Span Types](https://github.com/dotnet/csharplang/issues/8714) | [FirstClassSpan](https://github.com/dotnet/roslyn/tree/features/FirstClassSpan) | [Merged into 17.13p1](https://github.com/dotnet/roslyn/issues/73445) | [jjonescz](https://github.com/jjonescz) | [cston](https://github.com/cston), [333fred](https://github.com/333fred) | | [333fred](https://github.com/333fred), [stephentoub](https://github.com/stephentoub) |
+| [Unbound generic types in `nameof`](https://github.com/dotnet/csharplang/issues/8662) | [PR](https://github.com/dotnet/roslyn/pull/75368) | [Merged into 17.13p2](https://github.com/dotnet/roslyn/pull/75368) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [jcouv](https://github.com/jcouv), [AlekseyTs](https://github.com/AlekseyTs) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) |
+| [String literals in data section as UTF8](https://github.com/dotnet/roslyn/blob/main/docs/features/string-literals-data-section.md) | [PR](https://github.com/dotnet/roslyn/pull/76036) | [Merged into 17.13p4](https://github.com/dotnet/roslyn/issues/76234) | [jjonescz](https://github.com/jjonescz) | [AlekseyTs](https://github.com/AlekseyTs), [cston](https://github.com/cston) | N/A | N/A |
+| [Simple lambda parameters with modifiers](https://github.com/dotnet/csharplang/issues/8637) | [PR](https://github.com/dotnet/roslyn/pull/75400) | [Merged into 17.14p1](https://github.com/dotnet/roslyn/pull/75400) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [jjonescz](https://github.com/jjonescz), [cston](https://github.com/cston) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) |
+| [Partial Events and Constructors](https://github.com/dotnet/csharplang/issues/9058) | [PartialEventsCtors](https://github.com/dotnet/roslyn/tree/features/PartialEventsCtors) | [Merged into 17.14p3](https://github.com/dotnet/roslyn/issues/76859) | [jjonescz](https://github.com/jjonescz) | [cston](https://github.com/cston), [RikkiGibson](https://github.com/RikkiGibson) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [jaredpar](https://github.com/jaredpar) |
+| [Extensions](https://github.com/dotnet/csharplang/issues/8697) | [extensions](https://github.com/dotnet/roslyn/tree/features/extensions) | [Merged into 17.14p3](https://github.com/dotnet/roslyn/issues/76130) | [jcouv](https://github.com/jcouv), [AlekseyTs](https://github.com/AlekseyTs) | [jjonescz](https://github.com/jjonescz), TBD | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [MadsTorgersen](https://github.com/MadsTorgersen) |
+| [Null-conditional assignment](https://github.com/dotnet/csharplang/issues/8677) | [null-conditional-assignment](https://github.com/dotnet/roslyn/tree/features/null-conditional-assignment) | [Merged into 17.14p3](https://github.com/dotnet/roslyn/issues/75554) | [RikkiGibson](https://github.com/RikkiGibson) | [cston](https://github.com/cston), [jjonescz](https://github.com/jjonescz) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [RikkiGibson](https://github.com/RikkiGibson) |
+| [Ignored directives](https://github.com/dotnet/csharplang/issues/8617) | [PR](https://github.com/dotnet/roslyn/pull/77696) | Merged into 17.14p3 | [jjonescz](https://github.com/jjonescz) | [RikkiGibson](https://github.com/RikkiGibson), [jaredpar](https://github.com/jaredpar) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [jaredpar](https://github.com/jaredpar) |
+| [User Defined Compound Assignment Operators](https://github.com/dotnet/csharplang/issues/9101) | [UserDefinedCompoundAssignment](https://github.com/dotnet/roslyn/tree/features/UserDefinedCompoundAssignment) | [Merged to main](https://github.com/dotnet/roslyn/issues/76934) | [AlekseyTs](https://github.com/AlekseyTs) | [333fred](https://github.com/333fred), [cston](https://github.com/cston) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [AlekseyTs](https://github.com/AlekseyTs) |
+| [Optional and named arguments in `Expression` trees](https://github.com/dotnet/csharplang/issues/9246) | [PR](https://github.com/dotnet/roslyn/pull/77972) | Merged to main(https://github.com/dotnet/roslyn/issues/76934) | [cston](https://github.com/cston) | [333fred](https://github.com/333fred), [AlekseyTs](https://github.com/AlekseyTs) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) | [cston](https://github.com/cston) |
 
 # C# 13.0
 

src/Analyzers/CSharp/CodeFixes/UpgradeProject/CSharpUpgradeProjectCodeFixProvider.cs

@@ -56,6 +56,7 @@ internal sealed class CSharpUpgradeProjectCodeFixProvider() : AbstractUpgradePro
         "CS9194",
         "CS9202",
         "CS9260",
+        "CS9327"
     ];
 
     public override string UpgradeThisProjectResource => CSharpCodeFixesResources.Upgrade_this_project_to_csharp_language_version_0;

src/Analyzers/CSharp/Tests/GenerateMethod/GenerateMethodTests.cs

@@ -10575,7 +10575,7 @@ private int Goo()
                     throw new NotImplementedException();
                 }
             }
-            """, new(parseOptions: CSharpParseOptions.Default.WithLanguageVersion(LanguageVersionExtensions.CSharpNext)));
+            """, new(parseOptions: CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp14)));
 
     [Fact]
     public Task TestNullConditionalAssignment2()
@@ -10612,5 +10612,5 @@ private int Goo()
                     throw new NotImplementedException();
                 }
             }
-            """, new(parseOptions: CSharpParseOptions.Default.WithLanguageVersion(LanguageVersionExtensions.CSharpNext)));
+            """, new(parseOptions: CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp14)));
 }

src/Analyzers/CSharp/Tests/ImplementInterface/ImplementInterfaceCodeFixTests.cs

@@ -11836,7 +11836,7 @@ class C1 : I1
                 }
                 """,
             ReferenceAssemblies = ReferenceAssemblies.Net.Net80,
-            LanguageVersion = LanguageVersionExtensions.CSharpNext,
+            LanguageVersion = LanguageVersion.CSharp14,
         }.RunAsync();
 
     [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/78281")]
@@ -11878,7 +11878,7 @@ class C1 : I1
                 """,
             CodeActionIndex = 1,
             ReferenceAssemblies = ReferenceAssemblies.Net.Net80,
-            LanguageVersion = LanguageVersionExtensions.CSharpNext,
+            LanguageVersion = LanguageVersion.CSharp14,
         }.RunAsync();
 
     [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/79584")]
@@ -11900,7 +11900,7 @@ class C : IDisposable
                 """.Replace("\r\n", "\n"),
              CodeActionIndex = 1,
              ReferenceAssemblies = ReferenceAssemblies.Net.Net80,
-             LanguageVersion = LanguageVersionExtensions.CSharpNext,
+             LanguageVersion = LanguageVersion.CSharp14,
              Options = { { FormattingOptions2.NewLine, "\n" } },
          }.RunAsync();
 }

src/Analyzers/CSharp/Tests/UpgradeProject/UpgradeProjectTests.cs

@@ -1153,4 +1153,15 @@ void M2(ref int y)
             """,
             expected: LanguageVersion.CSharp12,
             new CSharpParseOptions(LanguageVersion.CSharp11));
+
+    [Fact]
+    public Task UpgradeProjectForUserDefinedCompoundAssignment()
+        => TestLanguageVersionUpgradedAsync("""
+            class C
+            {
+                public C operator [|+=|](C c) => c;
+            }
+            """,
+            expected: LanguageVersion.CSharp14,
+            new CSharpParseOptions(LanguageVersion.CSharp13));
 }

src/Analyzers/CSharp/Tests/UseAutoProperty/UseAutoPropertyTests_Field.cs

@@ -15,7 +15,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.UseAutoProperty;
 public sealed partial class UseAutoPropertyTests
 {
     private static readonly ParseOptions CSharp13 = CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp13);
-    private static readonly ParseOptions CSharp14 = CSharpParseOptions.Default.WithLanguageVersion(LanguageVersionExtensions.CSharpNext);
+    private static readonly ParseOptions CSharp14 = CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp14);
 
     [Fact]
     public Task TestNotInCSharp13()

src/Analyzers/CSharp/Tests/UseConditionalExpression/UseConditionalExpressionForAssignmentTests.cs

@@ -2365,5 +2365,5 @@ void M(C c)
                 }
             }
             """,
-            languageVersion: LanguageVersionExtensions.CSharpNext);
+            languageVersion: LanguageVersion.CSharp14);
 }

src/Analyzers/CSharp/Tests/UseExpressionBody/UseExpressionBodyForPropertiesAnalyzerTests.cs

@@ -542,7 +542,7 @@ object Goo
                 } = new();
             }
             """;
-        await TestWithUseExpressionBody(code, code, LanguageVersionExtensions.CSharpNext);
+        await TestWithUseExpressionBody(code, code, LanguageVersion.CSharp14);
     }
 
     [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/77473")]
@@ -560,6 +560,6 @@ object Goo
                 } = new();
             }
             """;
-        await TestWithUseExpressionBody(code, code, LanguageVersionExtensions.CSharpNext);
+        await TestWithUseExpressionBody(code, code, LanguageVersion.CSharp14);
     }
 }

src/Analyzers/CSharp/Tests/UseImplicitlyTypedLambdaExpression/UseImplicitlyTypedLambdaExpressionTests.cs

@@ -19,7 +19,7 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.UseImplicitlyTypedLambd
 [Trait(Traits.Feature, Traits.Features.CodeActionsUseImplicitObjectCreation)]
 public sealed class UseImplicitlyTypedLambdaExpressionTests
 {
-    private static readonly LanguageVersion CSharp14 = LanguageVersionExtensions.CSharpNext;
+    private static readonly LanguageVersion CSharp14 = LanguageVersion.CSharp14;
 
     [Fact]
     public Task TestAssignedToObject()

src/Analyzers/CSharp/Tests/UseNullPropagation/UseNullPropagationTests.cs

@@ -2377,7 +2377,7 @@ void M(C c)
                 }
             }
             """,
-            languageVersion: LanguageVersionExtensions.CSharpNext);
+            languageVersion: LanguageVersion.CSharp14);
 
     [Fact]
     public Task TestNullConditionalAssignment2()
@@ -2431,7 +2431,7 @@ void M(C c)
                 }
             }
             """,
-            languageVersion: LanguageVersionExtensions.CSharpNext);
+            languageVersion: LanguageVersion.CSharp14);
 
     [Fact]
     public Task TestNullAssignmentAfterOperation2()
@@ -2469,7 +2469,7 @@ void M(C c)
                 }
             }
             """,
-            languageVersion: LanguageVersionExtensions.CSharpNext);
+            languageVersion: LanguageVersion.CSharp14);
 
     [Fact]
     public Task TestNotNullAssignmentAfterOperation1()
@@ -2491,7 +2491,7 @@ void M(C c)
                 }
             }
             """,
-            languageVersion: LanguageVersionExtensions.CSharpNext);
+            languageVersion: LanguageVersion.CSharp14);
 
     [Fact]
     public Task TestNotNullAssignmentAfterOperation2()
@@ -2513,7 +2513,7 @@ void M(C c)
                 }
             }
             """,
-            languageVersion: LanguageVersionExtensions.CSharpNext);
+            languageVersion: LanguageVersion.CSharp14);
 
     [Fact]
     public Task TestNotNullAssignmentAfterOperation3()
@@ -2535,7 +2535,7 @@ void M(C c, C d)
                 }
             }
             """,
-            languageVersion: LanguageVersionExtensions.CSharpNext);
+            languageVersion: LanguageVersion.CSharp14);
 
     [Fact]
     public Task TestNotNullAssignmentAfterOperation4()
@@ -2557,7 +2557,7 @@ void M(C c)
                 }
             }
             """,
-            languageVersion: LanguageVersionExtensions.CSharpNext);
+            languageVersion: LanguageVersion.CSharp14);
 
     [Fact]
     public Task TestNullAssignmentAfterOperation_TopLevel1()
@@ -2591,7 +2591,7 @@ class C
             }
             """,
             OutputKind.ConsoleApplication,
-            LanguageVersionExtensions.CSharpNext);
+            LanguageVersion.CSharp14);
 
     [Fact]
     public Task TestNullAssignmentAfterOperation_TopLevel2()
@@ -2627,7 +2627,7 @@ class C
             }
             """,
             OutputKind.ConsoleApplication,
-            LanguageVersionExtensions.CSharpNext);
+            LanguageVersion.CSharp14);
 
     [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/79338")]
     public Task TestNestedNullPropagation_DifferentForms()
@@ -2663,5 +2663,5 @@ void M(C c)
                 void X(string s) { }
             }
             """,
-            languageVersion: LanguageVersionExtensions.CSharpNext);
+            languageVersion: LanguageVersion.CSharp14);
 }