List pattern syntax

eng/targets/Settings.props

@@ -207,7 +207,8 @@
  and hence suppress this warning until we get closer to release and a more
  thorough documentation story
  -->
- <NoWarn>$(NoWarn);1573;1591;1701</NoWarn>
+ <!-- PROTOTYPE(list-patterns) PublicAPIs -->
+ <NoWarn>$(NoWarn);1573;1591;1701;RS0016</NoWarn>
  </PropertyGroup>
  <PropertyGroup>
  <DefineConstants Condition="'$(InitialDefineConstants)' != ''">$(DefineConstants);$(InitialDefineConstants)</DefineConstants>

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -6606,4 +6606,13 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
  <data name="ERR_InheritingFromRecordWithSealedToString" xml:space="preserve">
  <value>Inheriting from a record with a sealed 'Object.ToString' is not supported in C# {0}. Please use language version '{1}' or greater.</value>
  </data>
+ <data name="IDS_FeatureListPattern" xml:space="preserve">
+ <value>list pattern</value>
+ </data>
+ <data name="IDS_FeatureSlicePattern" xml:space="preserve">
+ <value>slice pattern</value>
+ </data>
+ <data name="IDS_FeatureLengthPattern" xml:space="preserve">
+ <value>length pattern</value>
+ </data>
 </root>

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

@@ -4418,6 +4418,7 @@ private SymbolInfo GetNamedArgumentSymbolInfo(IdentifierNameSyntax identifierNam
  return (object)tupleElement == null ? SymbolInfo.None : new SymbolInfo(tupleElement, ImmutableArray<ISymbol>.Empty, CandidateReason.None);
  }
 
+ // PROTOTYPE(list-patterns) SyntaxKind.ListPatternClause
  if (parent3.IsKind(SyntaxKind.PropertyPatternClause) || parent3.IsKind(SyntaxKind.PositionalPatternClause))
  {
  return GetSymbolInfoWorker(identifierNameSyntax, SymbolInfoOptions.DefaultOptions, cancellationToken);

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

@@ -191,6 +191,11 @@ internal enum MessageID
  IDS_FeatureExternLocalFunctions = MessageBase + 12767,
  IDS_FeatureMemberNotNull = MessageBase + 12768,
 
+ // PROTOTYPE(list-patterns) To reduce conflicts with upstream. Should be moved eventually.
+ IDS_FeatureListPattern = MessageBase + 12800,
+ IDS_FeatureSlicePattern,
+ IDS_FeatureLengthPattern,
+
  IDS_FeatureNativeInt = MessageBase + 12769,
  IDS_FeatureImplicitObjectCreation = MessageBase + 12770,
  IDS_FeatureTypePattern = MessageBase + 12771,
@@ -491,6 +496,12 @@ internal static LanguageVersion RequiredVersion(this MessageID feature)
 
  default:
  throw ExceptionUtilities.UnexpectedValue(feature);
+
+ // PROTOTYPE(list-patterns)
+ case MessageID.IDS_FeatureListPattern:
+ case MessageID.IDS_FeatureSlicePattern:
+ case MessageID.IDS_FeatureLengthPattern:
+ return LanguageVersion.Preview;
  }
  }
  }

src/Compilers/CSharp/Portable/Generated/CSharpSyntaxGenerator/CSharpSyntaxGenerator.SourceGenerator/Syntax.xml.Main.Generated.cs

@@ -273,6 +273,9 @@ public partial class CSharpSyntaxVisitor<TResult>
  /// <summary>Called when the visitor visits a RecursivePatternSyntax node.</summary>
  public virtual TResult? VisitRecursivePattern(RecursivePatternSyntax node) => this.DefaultVisit(node);
 
+ /// <summary>Called when the visitor visits a LengthPatternClauseSyntax node.</summary>
+ public virtual TResult? VisitLengthPatternClause(LengthPatternClauseSyntax node) => this.DefaultVisit(node);
+
  /// <summary>Called when the visitor visits a PositionalPatternClauseSyntax node.</summary>
  public virtual TResult? VisitPositionalPatternClause(PositionalPatternClauseSyntax node) => this.DefaultVisit(node);
 
@@ -300,6 +303,9 @@ public partial class CSharpSyntaxVisitor<TResult>
  /// <summary>Called when the visitor visits a UnaryPatternSyntax node.</summary>
  public virtual TResult? VisitUnaryPattern(UnaryPatternSyntax node) => this.DefaultVisit(node);
 
+ /// <summary>Called when the visitor visits a SlicePatternSyntax node.</summary>
+ public virtual TResult? VisitSlicePattern(SlicePatternSyntax node) => this.DefaultVisit(node);
+
  /// <summary>Called when the visitor visits a InterpolatedStringTextSyntax node.</summary>
  public virtual TResult? VisitInterpolatedStringText(InterpolatedStringTextSyntax node) => this.DefaultVisit(node);
 
@@ -969,6 +975,9 @@ public partial class CSharpSyntaxVisitor
  /// <summary>Called when the visitor visits a RecursivePatternSyntax node.</summary>
  public virtual void VisitRecursivePattern(RecursivePatternSyntax node) => this.DefaultVisit(node);
 
+ /// <summary>Called when the visitor visits a LengthPatternClauseSyntax node.</summary>
+ public virtual void VisitLengthPatternClause(LengthPatternClauseSyntax node) => this.DefaultVisit(node);
+
  /// <summary>Called when the visitor visits a PositionalPatternClauseSyntax node.</summary>
  public virtual void VisitPositionalPatternClause(PositionalPatternClauseSyntax node) => this.DefaultVisit(node);
 
@@ -996,6 +1005,9 @@ public partial class CSharpSyntaxVisitor
  /// <summary>Called when the visitor visits a UnaryPatternSyntax node.</summary>
  public virtual void VisitUnaryPattern(UnaryPatternSyntax node) => this.DefaultVisit(node);
 
+ /// <summary>Called when the visitor visits a SlicePatternSyntax node.</summary>
+ public virtual void VisitSlicePattern(SlicePatternSyntax node) => this.DefaultVisit(node);
+
  /// <summary>Called when the visitor visits a InterpolatedStringTextSyntax node.</summary>
  public virtual void VisitInterpolatedStringText(InterpolatedStringTextSyntax node) => this.DefaultVisit(node);
 
@@ -1663,7 +1675,10 @@ public partial class CSharpSyntaxRewriter : CSharpSyntaxVisitor<SyntaxNode?>
  => node.Update(VisitToken(node.VarKeyword), (VariableDesignationSyntax?)Visit(node.Designation) ?? throw new ArgumentNullException("designation"));
 
  public override SyntaxNode? VisitRecursivePattern(RecursivePatternSyntax node)
- => node.Update((TypeSyntax?)Visit(node.Type), (PositionalPatternClauseSyntax?)Visit(node.PositionalPatternClause), (PropertyPatternClauseSyntax?)Visit(node.PropertyPatternClause), (VariableDesignationSyntax?)Visit(node.Designation));
+ => node.Update((TypeSyntax?)Visit(node.Type), (PositionalPatternClauseSyntax?)Visit(node.PositionalPatternClause), (LengthPatternClauseSyntax?)Visit(node.LengthPatternClause), (PropertyPatternClauseSyntax?)Visit(node.PropertyPatternClause), (VariableDesignationSyntax?)Visit(node.Designation));
+
+ public override SyntaxNode? VisitLengthPatternClause(LengthPatternClauseSyntax node)
+ => node.Update(VisitToken(node.OpenBracketToken), (PatternSyntax?)Visit(node.Pattern) ?? throw new ArgumentNullException("pattern"), VisitToken(node.CloseBracketToken));
 
  public override SyntaxNode? VisitPositionalPatternClause(PositionalPatternClauseSyntax node)
  => node.Update(VisitToken(node.OpenParenToken), VisitList(node.Subpatterns), VisitToken(node.CloseParenToken));
@@ -1692,6 +1707,9 @@ public partial class CSharpSyntaxRewriter : CSharpSyntaxVisitor<SyntaxNode?>
  public override SyntaxNode? VisitUnaryPattern(UnaryPatternSyntax node)
  => node.Update(VisitToken(node.OperatorToken), (PatternSyntax?)Visit(node.Pattern) ?? throw new ArgumentNullException("pattern"));
 
+ public override SyntaxNode? VisitSlicePattern(SlicePatternSyntax node)
+ => node.Update(VisitToken(node.DotDotToken), (PatternSyntax?)Visit(node.Pattern));
+
  public override SyntaxNode? VisitInterpolatedStringText(InterpolatedStringTextSyntax node)
  => node.Update(VisitToken(node.TextToken));
 
@@ -3552,14 +3570,27 @@ public static VarPatternSyntax VarPattern(VariableDesignationSyntax designation)
  => SyntaxFactory.VarPattern(SyntaxFactory.Token(SyntaxKind.VarKeyword), designation);
 
  /// <summary>Creates a new RecursivePatternSyntax instance.</summary>
- public static RecursivePatternSyntax RecursivePattern(TypeSyntax? type, PositionalPatternClauseSyntax? positionalPatternClause, PropertyPatternClauseSyntax? propertyPatternClause, VariableDesignationSyntax? designation)
+ public static RecursivePatternSyntax RecursivePattern(TypeSyntax? type, PositionalPatternClauseSyntax? positionalPatternClause, LengthPatternClauseSyntax? lengthPatternClause, PropertyPatternClauseSyntax? propertyPatternClause, VariableDesignationSyntax? designation)
  {
- return (RecursivePatternSyntax)Syntax.InternalSyntax.SyntaxFactory.RecursivePattern(type == null ? null : (Syntax.InternalSyntax.TypeSyntax)type.Green, positionalPatternClause == null ? null : (Syntax.InternalSyntax.PositionalPatternClauseSyntax)positionalPatternClause.Green, propertyPatternClause == null ? null : (Syntax.InternalSyntax.PropertyPatternClauseSyntax)propertyPatternClause.Green, designation == null ? null : (Syntax.InternalSyntax.VariableDesignationSyntax)designation.Green).CreateRed();
+ return (RecursivePatternSyntax)Syntax.InternalSyntax.SyntaxFactory.RecursivePattern(type == null ? null : (Syntax.InternalSyntax.TypeSyntax)type.Green, positionalPatternClause == null ? null : (Syntax.InternalSyntax.PositionalPatternClauseSyntax)positionalPatternClause.Green, lengthPatternClause == null ? null : (Syntax.InternalSyntax.LengthPatternClauseSyntax)lengthPatternClause.Green, propertyPatternClause == null ? null : (Syntax.InternalSyntax.PropertyPatternClauseSyntax)propertyPatternClause.Green, designation == null ? null : (Syntax.InternalSyntax.VariableDesignationSyntax)designation.Green).CreateRed();
  }
 
  /// <summary>Creates a new RecursivePatternSyntax instance.</summary>
  public static RecursivePatternSyntax RecursivePattern()
- => SyntaxFactory.RecursivePattern(default, default, default, default);
+ => SyntaxFactory.RecursivePattern(default, default, default, default, default);
+
+ /// <summary>Creates a new LengthPatternClauseSyntax instance.</summary>
+ public static LengthPatternClauseSyntax LengthPatternClause(SyntaxToken openBracketToken, PatternSyntax pattern, SyntaxToken closeBracketToken)
+ {
+ if (openBracketToken.Kind() != SyntaxKind.OpenBracketToken) throw new ArgumentException(nameof(openBracketToken));
+ if (pattern == null) throw new ArgumentNullException(nameof(pattern));
+ if (closeBracketToken.Kind() != SyntaxKind.CloseBracketToken) throw new ArgumentException(nameof(closeBracketToken));
+ return (LengthPatternClauseSyntax)Syntax.InternalSyntax.SyntaxFactory.LengthPatternClause((Syntax.InternalSyntax.SyntaxToken)openBracketToken.Node!, (Syntax.InternalSyntax.PatternSyntax)pattern.Green, (Syntax.InternalSyntax.SyntaxToken)closeBracketToken.Node!).CreateRed();
+ }
+
+ /// <summary>Creates a new LengthPatternClauseSyntax instance.</summary>
+ public static LengthPatternClauseSyntax LengthPatternClause(PatternSyntax pattern)
+ => SyntaxFactory.LengthPatternClause(SyntaxFactory.Token(SyntaxKind.OpenBracketToken), pattern, SyntaxFactory.Token(SyntaxKind.CloseBracketToken));
 
  /// <summary>Creates a new PositionalPatternClauseSyntax instance.</summary>
  public static PositionalPatternClauseSyntax PositionalPatternClause(SyntaxToken openParenToken, SeparatedSyntaxList<SubpatternSyntax> subpatterns, SyntaxToken closeParenToken)
@@ -3574,16 +3605,22 @@ public static PositionalPatternClauseSyntax PositionalPatternClause(SeparatedSyn
  => SyntaxFactory.PositionalPatternClause(SyntaxFactory.Token(SyntaxKind.OpenParenToken), subpatterns, SyntaxFactory.Token(SyntaxKind.CloseParenToken));
 
  /// <summary>Creates a new PropertyPatternClauseSyntax instance.</summary>
- public static PropertyPatternClauseSyntax PropertyPatternClause(SyntaxToken openBraceToken, SeparatedSyntaxList<SubpatternSyntax> subpatterns, SyntaxToken closeBraceToken)
+ public static PropertyPatternClauseSyntax PropertyPatternClause(SyntaxKind kind, SyntaxToken openBraceToken, SeparatedSyntaxList<SubpatternSyntax> subpatterns, SyntaxToken closeBraceToken)
  {
+ switch (kind)
+ {
+ case SyntaxKind.PropertyPatternClause:
+ case SyntaxKind.ListPatternClause: break;
+ default: throw new ArgumentException(nameof(kind));
+ }
  if (openBraceToken.Kind() != SyntaxKind.OpenBraceToken) throw new ArgumentException(nameof(openBraceToken));
  if (closeBraceToken.Kind() != SyntaxKind.CloseBraceToken) throw new ArgumentException(nameof(closeBraceToken));
- return (PropertyPatternClauseSyntax)Syntax.InternalSyntax.SyntaxFactory.PropertyPatternClause((Syntax.InternalSyntax.SyntaxToken)openBraceToken.Node!, subpatterns.Node.ToGreenSeparatedList<Syntax.InternalSyntax.SubpatternSyntax>(), (Syntax.InternalSyntax.SyntaxToken)closeBraceToken.Node!).CreateRed();
+ return (PropertyPatternClauseSyntax)Syntax.InternalSyntax.SyntaxFactory.PropertyPatternClause(kind, (Syntax.InternalSyntax.SyntaxToken)openBraceToken.Node!, subpatterns.Node.ToGreenSeparatedList<Syntax.InternalSyntax.SubpatternSyntax>(), (Syntax.InternalSyntax.SyntaxToken)closeBraceToken.Node!).CreateRed();
  }
 
  /// <summary>Creates a new PropertyPatternClauseSyntax instance.</summary>
- public static PropertyPatternClauseSyntax PropertyPatternClause(SeparatedSyntaxList<SubpatternSyntax> subpatterns = default)
- => SyntaxFactory.PropertyPatternClause(SyntaxFactory.Token(SyntaxKind.OpenBraceToken), subpatterns, SyntaxFactory.Token(SyntaxKind.CloseBraceToken));
+ public static PropertyPatternClauseSyntax PropertyPatternClause(SyntaxKind kind, SeparatedSyntaxList<SubpatternSyntax> subpatterns = default)
+ => SyntaxFactory.PropertyPatternClause(kind, SyntaxFactory.Token(SyntaxKind.OpenBraceToken), subpatterns, SyntaxFactory.Token(SyntaxKind.CloseBraceToken));
 
  /// <summary>Creates a new SubpatternSyntax instance.</summary>
  public static SubpatternSyntax Subpattern(NameColonSyntax? nameColon, PatternSyntax pattern)
@@ -3684,6 +3721,17 @@ public static UnaryPatternSyntax UnaryPattern(SyntaxToken operatorToken, Pattern
  public static UnaryPatternSyntax UnaryPattern(PatternSyntax pattern)
  => SyntaxFactory.UnaryPattern(SyntaxFactory.Token(SyntaxKind.NotKeyword), pattern);
 
+ /// <summary>Creates a new SlicePatternSyntax instance.</summary>
+ public static SlicePatternSyntax SlicePattern(SyntaxToken dotDotToken, PatternSyntax? pattern)
+ {
+ if (dotDotToken.Kind() != SyntaxKind.DotDotToken) throw new ArgumentException(nameof(dotDotToken));
+ return (SlicePatternSyntax)Syntax.InternalSyntax.SyntaxFactory.SlicePattern((Syntax.InternalSyntax.SyntaxToken)dotDotToken.Node!, pattern == null ? null : (Syntax.InternalSyntax.PatternSyntax)pattern.Green).CreateRed();
+ }
+
+ /// <summary>Creates a new SlicePatternSyntax instance.</summary>
+ public static SlicePatternSyntax SlicePattern(PatternSyntax? pattern = default)
+ => SyntaxFactory.SlicePattern(SyntaxFactory.Token(SyntaxKind.DotDotToken), pattern);
+
  /// <summary>Creates a new InterpolatedStringTextSyntax instance.</summary>
  public static InterpolatedStringTextSyntax InterpolatedStringText(SyntaxToken textToken)
  {