Merge pull request #54394 from dotnet/merges/main-to-main-vs-deps

Merge main to main-vs-deps

.git-blame-ignore-revs

@@ -0,0 +1,2 @@
+# Dotnet-format -w Roslyn.sln
+abce41d282ac631be5217140f1bd46d0e250ad02

docs/Language Feature Status.md

@@ -10,27 +10,32 @@ efforts behind them.
 
 | Feature | Branch | State | Developer | Reviewer | LDM Champ |
 | ------- | ------ | ----- | --------- | -------- | --------- |
-| [Record structs](https://github.com/dotnet/csharplang/issues/4334) | [record-structs](https://github.com/dotnet/roslyn/tree/features/record-structs) | [Merged into 16.11](https://github.com/dotnet/roslyn/issues/51199) | [jcouv](https://github.com/jcouv) | [AlekseyTs](https://github.com/AlekseyTs), [RikkiGibson](https://github.com/RikkiGibson) | [jcouv](https://github.com/jcouv) |
-| [Global Using Directive](https://github.com/dotnet/csharplang/issues/3428) | [GlobalUsingDirective](https://github.com/dotnet/roslyn/tree/features/GlobalUsingDirective) | [Merged into 16.11](https://github.com/dotnet/roslyn/issues/51307) | [AlekseyTs](https://github.com/AlekseyTs) | [333fred](https://github.com/333fred), [cston](https://github.com/cston) | [AlekseyTs](https://github.com/AlekseyTs) |
 | [Static Abstract Members In Interfaces](https://github.com/dotnet/csharplang/issues/4436) | [StaticAbstractMembersInInterfaces](https://github.com/dotnet/roslyn/tree/features/StaticAbstractMembersInInterfaces) | [In Progress](https://github.com/dotnet/roslyn/issues/52221) | [AlekseyTs](https://github.com/AlekseyTs) | [333fred](https://github.com/333fred), [RikkiGibson](https://github.com/RikkiGibson) | [MadsTorgersen](https://github.com/MadsTorgersen) |
 | [File-scoped namespace](https://github.com/dotnet/csharplang/issues/137) | [FileScopedNamespaces](https://github.com/dotnet/roslyn/tree/features/FileScopedNamespaces) | [In Progress](https://github.com/dotnet/roslyn/issues/49000) | [RikkiGibson](https://github.com/RikkiGibson) | [jcouv](https://github.com/jcouv), [chsienki](https://github.com/chsienki) | [CyrusNajmabadi](https://github.com/CyrusNajmabadi) |
 | [Interpolated string improvements](https://github.com/dotnet/csharplang/issues/4487) | [interpolated-string](https://github.com/dotnet/roslyn/tree/features/interpolated-string) | [In Progress](https://github.com/dotnet/roslyn/issues/51499) | [333fred](https://github.com/333fred) | [AlekseyTs](https://github.com/AlekseyTs), [chsienki](https://github.com/chsienki) | [jaredpar](https://github.com/jaredpar) |
 | [Parameterless struct constructors](https://github.com/dotnet/csharplang/issues/99) | [struct-ctors](https://github.com/dotnet/roslyn/tree/features/struct-ctors) | [In Progress](https://github.com/dotnet/roslyn/issues/51698) | [cston](https://github.com/cston) | [jcouv](https://github.com/jcouv), [333fred](https://github.com/333fred) | [jcouv](https://github.com/jouv) |
 | [Lambda improvements](https://github.com/dotnet/csharplang/blob/main/proposals/lambda-improvements.md) | [lambdas](https://github.com/dotnet/roslyn/tree/features/lambdas) | [In Progress](https://github.com/dotnet/roslyn/issues/52192) | [cston](https://github.com/cston) | [333fred](https://github.com/333fred), [jcouv](https://github.com/jcouv) | [jaredpar](https://github.com/jaredpar) |
 | [nameof(parameter)](https://github.com/dotnet/csharplang/issues/373) | main | [In Progress](https://github.com/dotnet/roslyn/issues/40524) | [jcouv](https://github.com/jcouv) | TBD | [jcouv](https://github.com/jcouv) |
-| [Improved Definite Assignment](https://github.com/dotnet/csharplang/issues/4465) | [improved-definite-assignment](https://github.com/dotnet/roslyn/tree/features/improved-definite-assignment) | [Merged into 17.0](https://github.com/dotnet/roslyn/issues/51463) | [RikkiGibson](https://github.com/RikkiGibson) | [jcouv](https://github.com/jcouv) | [jaredpar](https://github.com/jaredpar) |
 | [Relax ordering of `ref` and `partial` modifiers](https://github.com/dotnet/csharplang/issues/946) | [ref-partial](https://github.com/dotnet/roslyn/tree/features/ref-partial) | In Progress | [alrz](https://github.com/alrz) | [gafter](https://github.com/gafter) | [jcouv](https://github.com/jcouv) |
 | [Parameter null-checking](https://github.com/dotnet/csharplang/issues/2145) | [param-nullchecking](https://github.com/dotnet/roslyn/tree/features/param-nullchecking) | [In Progress](https://github.com/dotnet/roslyn/issues/36024) | [fayrose](https://github.com/fayrose) | [agocke](https://github.com/agocke) | [jaredpar](https://github.com/jaredpar) |
 | [Caller expression attribute](https://github.com/dotnet/csharplang/issues/287) | [caller-argument-expression](https://github.com/dotnet/roslyn/tree/features/caller-argument-expression) | [In Progress](https://github.com/dotnet/roslyn/issues/52745) | [Youssef1313](https://github.com/Youssef1313) | [333fred](https://github.com/333fred),[AlekseyTs](https://github.com/AlekseyTs) | [jcouv](https://github.com/jcouv) |
 | [Generic attributes](https://github.com/dotnet/csharplang/issues/124) | [generic-attributes](https://github.com/dotnet/roslyn/tree/features/generic-attributes) | [In Progress](https://github.com/dotnet/roslyn/issues/36285) | [AviAvni](https://github.com/AviAvni) | [agocke](https://github.com/agocke) | [mattwar](https://github.com/mattwar) |
 | [Default in deconstruction](https://github.com/dotnet/roslyn/pull/25562) | [decon-default](https://github.com/dotnet/roslyn/tree/features/decon-default) | [Implemented](https://github.com/dotnet/roslyn/issues/25559) | [jcouv](https://github.com/jcouv) | [gafter](https://github.com/gafter) | [jcouv](https://github.com/jcouv) |
-| [Constant Interpolated Strings](https://github.com/dotnet/csharplang/issues/2951) | main | [Merged into 16.9p3](https://github.com/dotnet/roslyn/pull/49676) | [kevinsun-dev](https://github.com/kevinsun-dev) | [333fred](https://github.com/333fred) | [jaredar](https://github.com/jaredpar), [agocke](https://github.com/agocke) |
-| [Mix declarations and variables in deconstruction](https://github.com/dotnet/csharplang/issues/125) | main | [Merged into 16.10](https://github.com/dotnet/roslyn/issues/47746) | [YairHalberstadt ](https://github.com/YairHalberstadt) | [jcouv](https://github.com/jcouv) | [MadsTorgersen](https://github.com/MadsTorgersen) |
 | [List patterns](https://github.com/dotnet/csharplang/issues/3435) | [list-patterns](https://github.com/dotnet/roslyn/tree/features/list-patterns) | [In Progress](https://github.com/dotnet/roslyn/issues/51289) | [alrz](https://github.com/alrz) | [jcouv](https://github.com/jcouv), [333fred](https://github.com/333fred) | [333fred](https://github.com/333fred) |
+
+# C# 10.0
+
+| Feature | Branch | State | Developer | Reviewer | LDM Champ |
+| ------- | ------ | ----- | --------- | -------- | --------- |
+| [Record structs](https://github.com/dotnet/csharplang/issues/4334) | [record-structs](https://github.com/dotnet/roslyn/tree/features/record-structs) | [Merged into 16.11](https://github.com/dotnet/roslyn/issues/51199) | [jcouv](https://github.com/jcouv) | [AlekseyTs](https://github.com/AlekseyTs), [RikkiGibson](https://github.com/RikkiGibson) | [jcouv](https://github.com/jcouv) |
+| [Global Using Directive](https://github.com/dotnet/csharplang/issues/3428) | [GlobalUsingDirective](https://github.com/dotnet/roslyn/tree/features/GlobalUsingDirective) | [Merged into 16.11](https://github.com/dotnet/roslyn/issues/51307) | [AlekseyTs](https://github.com/AlekseyTs) | [333fred](https://github.com/333fred), [cston](https://github.com/cston) | [AlekseyTs](https://github.com/AlekseyTs) |
+| [Improved Definite Assignment](https://github.com/dotnet/csharplang/issues/4465) | [improved-definite-assignment](https://github.com/dotnet/roslyn/tree/features/improved-definite-assignment) | [Merged into 17.0](https://github.com/dotnet/roslyn/issues/51463) | [RikkiGibson](https://github.com/RikkiGibson) | [jcouv](https://github.com/jcouv) | [jaredpar](https://github.com/jaredpar) |
+| [Constant Interpolated Strings](https://github.com/dotnet/csharplang/issues/2951) | main | [Merged into 16.9p3](https://github.com/dotnet/roslyn/pull/49676) | [kevinsun-dev](https://github.com/kevinsun-dev) | [333fred](https://github.com/333fred) | [jaredar](https://github.com/jaredpar), [agocke](https://github.com/agocke) |
 | [Extended property patterns](https://github.com/dotnet/csharplang/issues/4394) | [extended-property-patterns](https://github.com/dotnet/roslyn/tree/features/extended-property-patterns) | [Merged into 17.0](https://github.com/dotnet/roslyn/issues/52468) | [alrz](https://github.com/alrz) | [jcouv](https://github.com/jcouv), [333fred](https://github.com/333fred) | [333fred](https://github.com/333fred) |
 | [Sealed record ToString](https://github.com/dotnet/csharplang/issues/4174) | main | [Merged](https://github.com/dotnet/roslyn/issues/52031) | [thomaslevesque](https://github.com/thomaslevesque/) | [jcouv](https://github.com/jcouv) | [333fred](https://github.com/333fred) |
-| [Source Generator V2 APIs](https://github.com/dotnet/roslyn/issues/51257) | [features/source-generators](https://github.com/dotnet/roslyn/tree/features/source-generators) | [In Progress](https://github.com/dotnet/roslyn/issues/51257) | [chsienki](https://github.com/chsienki/) | [rikkigibson](https://github.com/rikkigibson), [jaredpar](https://github.com/jaredpar), [cston](https://github.com/cston) | N/A |
-| [Async method builder override](https://github.com/dotnet/csharplang/issues/1407) | main | [In Progress](https://github.com/dotnet/roslyn/issues/51999) | [jcouv](https://github.com/jcouv) | TBD | [stephentoub](https://github.com/stephentoub) |
+| [Source Generator V2 APIs](https://github.com/dotnet/roslyn/issues/51257) | [features/source-generators](https://github.com/dotnet/roslyn/tree/features/source-generators) | [Merged into 17.0p2](https://github.com/dotnet/roslyn/issues/51257) | [chsienki](https://github.com/chsienki/) | [rikkigibson](https://github.com/rikkigibson), [jaredpar](https://github.com/jaredpar), [cston](https://github.com/cston) | N/A |
+| [Mix declarations and variables in deconstruction](https://github.com/dotnet/csharplang/issues/125) | main | [Merged into 16.10](https://github.com/dotnet/roslyn/issues/47746) | [YairHalberstadt ](https://github.com/YairHalberstadt) | [jcouv](https://github.com/jcouv) | [MadsTorgersen](https://github.com/MadsTorgersen) |
+| [Async method builder override](https://github.com/dotnet/csharplang/issues/1407) | main | [Merged into 17.0p2](https://github.com/dotnet/roslyn/issues/51999) | [jcouv](https://github.com/jcouv) | [cston](https://github.com/cston), [RikkiGibson](https://github.com/RikkiGibson) | [stephentoub](https://github.com/stephentoub) |
 
 # VB 16.9
 

dotnet-tools.json

@@ -2,7 +2,7 @@
  "isRoot": true,
  "tools": {
  "dotnet-format": {
- "version": "5.0.141503",
+ "version": "6.0.231801",
  "commands": [
  "dotnet-format"
  ]

eng/Version.Details.xml

@@ -6,9 +6,9 @@
  <Sha>7e80445ee82adbf9a8e6ae601ac5e239d982afaa</Sha>
  <SourceBuild RepoName="xliff-tasks" ManagedOnly="true" />
  </Dependency>
- <Dependency Name="Microsoft.SourceBuild.Intermediate.source-build" Version="0.1.0-alpha.1.21318.1">
+ <Dependency Name="Microsoft.SourceBuild.Intermediate.source-build" Version="0.1.0-alpha.1.21323.2">
  <Uri>https://github.com/dotnet/source-build</Uri>
- <Sha>3fb25b8db3bec654e37e71a5b2b7fde14444bc2f</Sha>
+ <Sha>c35d744cbe24f85d2165a5edb1730355b8cb916f</Sha>
  <SourceBuild RepoName="source-build" ManagedOnly="true" />
  </Dependency>
  </ProductDependencies>

src/Compilers/CSharp/Portable/Binder/MethodArgumentInfo.cs

@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -6418,6 +6418,9 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
  <data name="ERR_FeatureNotAvailableInVersion9" xml:space="preserve">
  <value>Feature '{0}' is not available in C# 9.0. Please use language version {1} or greater.</value>
  </data>
+ <data name="ERR_FeatureNotAvailableInVersion10" xml:space="preserve">
+ <value>Feature '{0}' is not available in C# 10.0. Please use language version {1} or greater.</value>
+ </data>
  <data name="ERR_UnexpectedArgumentList" xml:space="preserve">
  <value>Unexpected argument list.</value>
  </data>
@@ -6719,4 +6722,7 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
  <data name="ERR_BuilderAttributeDisallowed" xml:space="preserve">
  <value>The AsyncMethodBuilder attribute is disallowed on anonymous methods without an explicit return type.</value>
  </data>
+ <data name="ERR_SimpleProgramIsEmpty" xml:space="preserve">
+ <value>At least one top-level statement must be non-empty.</value>
+ </data>
 </root>

src/Compilers/CSharp/Portable/Compilation/MemberSemanticModel.cs

@@ -899,7 +899,7 @@ public override AwaitExpressionInfo GetAwaitExpressionInfo(AwaitExpressionSyntax
  throw new ArgumentException("node.Kind==" + node.Kind());
  }
 
- var bound = GetUpperBoundNode(node);
+ var bound = GetLowerBoundNode(node);
  BoundAwaitableInfo awaitableInfo = (((bound as BoundExpressionStatement)?.Expression ?? bound) as BoundAwaitExpression)?.AwaitableInfo;
  if (awaitableInfo == null)
  {

src/Compilers/CSharp/Portable/Declarations/DeclarationTreeBuilder.cs

@@ -59,6 +59,7 @@ private ImmutableArray<SingleNamespaceOrTypeDeclaration> VisitNamespaceChildren(
  bool isIterator = false;
  bool hasReturnWithExpression = false;
  GlobalStatementSyntax firstGlobalStatement = null;
+ bool hasNonEmptyGlobalSatement = false;
 
  var childrenBuilder = ArrayBuilder<SingleNamespaceOrTypeDeclaration>.GetInstance();
  foreach (var member in members)
@@ -74,6 +75,11 @@ private ImmutableArray<SingleNamespaceOrTypeDeclaration> VisitNamespaceChildren(
  firstGlobalStatement ??= global;
  var topLevelStatement = global.Statement;
 
+ if (!topLevelStatement.IsKind(SyntaxKind.EmptyStatement))
+ {
+ hasNonEmptyGlobalSatement = true;
+ }
+
  if (!hasAwaitExpressions)
  {
  hasAwaitExpressions = SyntaxFacts.HasAwaitOperations(topLevelStatement);
@@ -98,7 +104,16 @@ private ImmutableArray<SingleNamespaceOrTypeDeclaration> VisitNamespaceChildren(
  // wrap all global statements in a compilation unit into a simple program type:
  if (firstGlobalStatement is object)
  {
- childrenBuilder.Add(CreateSimpleProgram(firstGlobalStatement, hasAwaitExpressions, isIterator, hasReturnWithExpression));
+ var diagnostics = ImmutableArray<Diagnostic>.Empty;
+
+ if (!hasNonEmptyGlobalSatement)
+ {
+ var bag = DiagnosticBag.GetInstance();
+ bag.Add(ErrorCode.ERR_SimpleProgramIsEmpty, ((EmptyStatementSyntax)firstGlobalStatement.Statement).SemicolonToken.GetLocation());
+ diagnostics = bag.ToReadOnlyAndFree();
+ }
+
+ childrenBuilder.Add(CreateSimpleProgram(firstGlobalStatement, hasAwaitExpressions, isIterator, hasReturnWithExpression, diagnostics));
  }
 
  // wrap all members that are defined in a namespace or compilation unit into an implicit type:
@@ -130,7 +145,7 @@ private static SingleNamespaceOrTypeDeclaration CreateImplicitClass(ImmutableSeg
  diagnostics: ImmutableArray<Diagnostic>.Empty);
  }
 
- private static SingleNamespaceOrTypeDeclaration CreateSimpleProgram(GlobalStatementSyntax firstGlobalStatement, bool hasAwaitExpressions, bool isIterator, bool hasReturnWithExpression)
+ private static SingleNamespaceOrTypeDeclaration CreateSimpleProgram(GlobalStatementSyntax firstGlobalStatement, bool hasAwaitExpressions, bool isIterator, bool hasReturnWithExpression, ImmutableArray<Diagnostic> diagnostics)
  {
  return new SingleTypeDeclaration(
  kind: DeclarationKind.SimpleProgram,
@@ -144,7 +159,7 @@ private static SingleNamespaceOrTypeDeclaration CreateSimpleProgram(GlobalStatem
  nameLocation: new SourceLocation(firstGlobalStatement.GetFirstToken()),
  memberNames: ImmutableSegmentedDictionary<string, VoidResult>.Empty,
  children: ImmutableArray<SingleTypeDeclaration>.Empty,
- diagnostics: ImmutableArray<Diagnostic>.Empty);
+ diagnostics: diagnostics);
  }
 
  /// <summary>

src/Compilers/CSharp/Portable/Errors/ErrorCode.cs

@@ -1958,6 +1958,8 @@ internal enum ErrorCode
  HDN_DuplicateWithGlobalUsing = 8933,
  ERR_CantConvAnonMethReturnType = 8934,
  ERR_BuilderAttributeDisallowed = 8935,
+ ERR_FeatureNotAvailableInVersion10 = 8936,
+ ERR_SimpleProgramIsEmpty = 8937,
 
  #endregion
 

src/Compilers/CSharp/Portable/Errors/MessageID.cs

@@ -335,6 +335,10 @@ internal static LanguageVersion RequiredVersion(this MessageID feature)
  switch (feature)
  {
  // C# preview features.
+ case MessageID.IDS_FeatureStaticAbstractMembersInInterfaces: // semantic check
+ return LanguageVersion.Preview;
+
+ // C# 10.0 features.
  case MessageID.IDS_FeatureMixedDeclarationsAndExpressionsInDeconstruction: // semantic check
  case MessageID.IDS_FeatureSealedToStringInRecord: // semantic check
  case MessageID.IDS_FeatureRecordStructs:
@@ -345,10 +349,10 @@ internal static LanguageVersion RequiredVersion(this MessageID feature)
  case MessageID.IDS_FeatureInferredDelegateType: // semantic check
  case MessageID.IDS_FeatureLambdaAttributes: // semantic check
  case MessageID.IDS_FeatureExtendedPropertyPatterns:
- case MessageID.IDS_FeatureStaticAbstractMembersInInterfaces: // semantic check
  case MessageID.IDS_FeatureLambdaReturnType: // semantic check
  case MessageID.IDS_AsyncMethodBuilderOverride: // semantic check
- return LanguageVersion.Preview;
+ case MessageID.IDS_FeatureConstantInterpolatedStrings: // semantic check
+ return LanguageVersion.CSharp10;
 
  // C# 9.0 features.
  case MessageID.IDS_FeatureLambdaDiscardParameters: // semantic check
@@ -375,12 +379,9 @@ internal static LanguageVersion RequiredVersion(this MessageID feature)
  case MessageID.IDS_FeatureStaticAnonymousFunction: // syntax check
  case MessageID.IDS_FeatureModuleInitializers: // semantic check on method attribute
  case MessageID.IDS_FeatureDefaultTypeParameterConstraint:
+ case MessageID.IDS_FeatureVarianceSafetyForStaticInterfaceMembers: // semantic check
  return LanguageVersion.CSharp9;
 
- case MessageID.IDS_FeatureVarianceSafetyForStaticInterfaceMembers: //semantic check
- case MessageID.IDS_FeatureConstantInterpolatedStrings: //semantic check
- return LanguageVersion.Preview;
-
  // C# 8.0 features.
  case MessageID.IDS_FeatureAltInterpolatedVerbatimStrings:
  case MessageID.IDS_FeatureCoalesceAssignmentExpression: