Use record keyword to display records (#46338)

src/Compilers/CSharp/Portable/SymbolDisplay/SymbolDisplayVisitor.Types.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Linq;
@@ -658,6 +659,11 @@ private void AddTypeKind(INamedTypeSymbol symbol)
                 {
                     switch (symbol.TypeKind)
                     {
+                        case TypeKind.Class when FindValidCloneMethod(symbol) is object:
+                            AddKeyword(SyntaxKind.RecordKeyword);
+                            AddSpace();
+                            break;
+
                         case TypeKind.Module:
                         case TypeKind.Class:
                             AddKeyword(SyntaxKind.ClassKeyword);
@@ -700,6 +706,61 @@ private void AddTypeKind(INamedTypeSymbol symbol)
             }
         }
 
+        /// <summary>
+        /// Copy of <see cref="SynthesizedRecordClone.FindValidCloneMethod(TypeSymbol, ref HashSet{DiagnosticInfo}?)"/>
+        /// </summary>
+        private static IMethodSymbol FindValidCloneMethod(ITypeSymbol containingType)
+        {
+            IMethodSymbol candidate = null;
+
+            foreach (var member in containingType.GetMembers(WellKnownMemberNames.CloneMethodName))
+            {
+                if (member is IMethodSymbol
+                {
+                    DeclaredAccessibility: Accessibility.Public,
+                    IsStatic: false,
+                    Parameters: { Length: 0 },
+                    Arity: 0
+                } method)
+                {
+                    if (candidate is object)
+                    {
+                        // An ambiguity case, can come from metadata, treat as an error for simplicity.
+                        return null;
+                    }
+
+                    candidate = method;
+                }
+            }
+
+            if (candidate is null ||
+                !(containingType.IsSealed || candidate.IsOverride || candidate.IsVirtual || candidate.IsAbstract) ||
+                !isEqualToOrDerivedFrom(
+                    containingType,
+                    candidate.ReturnType))
+            {
+                return null;
+            }
+
+            return candidate;
+
+            static bool isEqualToOrDerivedFrom(ITypeSymbol one, ITypeSymbol other)
+            {
+                do
+                {
+                    if (one.Equals(other, SymbolEqualityComparer.IgnoreAll))
+                    {
+                        return true;
+                    }
+
+                    one = one.BaseType;
+                }
+                while (one != null);
+
+                return false;
+            }
+        }
+
         private void AddTypeParameterVarianceIfRequired(ITypeParameterSymbol symbol)
         {
             if (format.GenericsOptions.IncludesOption(SymbolDisplayGenericsOptions.IncludeVariance))

src/Compilers/CSharp/Portable/Symbols/Synthesized/Records/SynthesizedRecordClone.cs

@@ -139,6 +139,7 @@ internal override void GenerateMethodBody(TypeCompilationState compilationState,
             throw ExceptionUtilities.Unreachable;
         }
 
+        // Note: this method was replicated in SymbolDisplayVisitor.FindValidCloneMethod
         internal static MethodSymbol? FindValidCloneMethod(TypeSymbol containingType, ref HashSet<DiagnosticInfo>? useSiteDiagnostics)
         {
             MethodSymbol? candidate = null;
@@ -155,7 +156,7 @@ internal override void GenerateMethodBody(TypeCompilationState compilationState,
                 {
                     if (candidate is object)
                     {
-                        // An ammbiguity case, can come from metadata, treat as an error for simplicity.
+                        // An ambiguity case, can come from metadata, treat as an error for simplicity.
                         return null;
                     }
 

src/Compilers/CSharp/Test/Semantic/Semantics/RecordTests.cs

@@ -1730,6 +1730,9 @@ public void Clone_01()
 
             Assert.True(clone.ContainingType.IsSealed);
             Assert.True(clone.ContainingType.IsAbstract);
+
+            Assert.Equal("record C1", comp.GlobalNamespace.GetTypeMember("C1")
+                .ToDisplayString(SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
         }
 
         [Fact]
@@ -1756,6 +1759,9 @@ public void Clone_02()
 
             Assert.True(clone.ContainingType.IsSealed);
             Assert.True(clone.ContainingType.IsAbstract);
+
+            Assert.Equal("record C1", comp.GlobalNamespace.GetTypeMember("C1")
+                .ToDisplayString(SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
         }
 
         [Fact]
@@ -1810,10 +1816,13 @@ public void Clone_04()
 
             Assert.True(clone.ContainingType.IsSealed);
             Assert.True(clone.ContainingType.IsAbstract);
+
+            Assert.Equal("record C1", comp.GlobalNamespace.GetTypeMember("C1")
+                .ToDisplayString(SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
         }
 
         [Fact]
-        public void Clone_05()
+        public void Clone_05_IntReturnType_UsedAsBaseType()
         {
             var ilSource = @"
 .class public auto ansi beforefieldinit A
@@ -1904,10 +1913,13 @@ .maxstack 8
                 // public record B : A {
                 Diagnostic(ErrorCode.ERR_BadRecordBase, "A").WithLocation(2, 19)
                 );
+
+            Assert.Equal("class A", comp.GlobalNamespace.GetTypeMember("A")
+                .ToDisplayString(SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
         }
 
         [Fact]
-        public void Clone_06()
+        public void Clone_06_IntReturnType_UsedInWith()
         {
             var ilSource = @"
 .class public auto ansi beforefieldinit A
@@ -2004,10 +2016,13 @@ static void Main()
                 //         A x = new A() with { };
                 Diagnostic(ErrorCode.ERR_NoSingleCloneMethod, "new A()").WithArguments("A").WithLocation(6, 15)
                 );
+
+            Assert.Equal("class A", comp.GlobalNamespace.GetTypeMember("A")
+                .ToDisplayString(SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
         }
 
         [Fact]
-        public void Clone_07()
+        public void Clone_07_Ambiguous_UsedAsBaseType()
         {
             var ilSource = @"
 .class public auto ansi beforefieldinit A
@@ -2108,10 +2123,13 @@ .maxstack 8
                 // public record B : A {
                 Diagnostic(ErrorCode.ERR_BadRecordBase, "A").WithLocation(2, 19)
                 );
+
+            Assert.Equal("class A", comp.GlobalNamespace.GetTypeMember("A")
+                .ToDisplayString(SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
         }
 
         [Fact]
-        public void Clone_08()
+        public void Clone_08_Ambiguous_UsedInWith()
         {
             var ilSource = @"
 .class public auto ansi beforefieldinit A
@@ -2218,16 +2236,18 @@ static void Main()
                 //         A x = new A() with { };
                 Diagnostic(ErrorCode.ERR_NoSingleCloneMethod, "new A()").WithArguments("A").WithLocation(6, 15)
                 );
+
+            Assert.Equal("class A", comp.GlobalNamespace.GetTypeMember("A")
+                .ToDisplayString(SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
         }
 
         [Fact]
-        public void Clone_09()
+        public void Clone_09_AmbiguousReverseOrder_UsedAsBaseType()
         {
             var ilSource = @"
 .class public auto ansi beforefieldinit A
     extends System.Object
 {
-    // Methods
     // Methods
     .method public hidebysig specialname newslot virtual 
         instance class A '" + WellKnownMemberNames.CloneMethodName + @"' () cil managed 
@@ -2322,10 +2342,13 @@ .maxstack 8
                 // public record B : A {
                 Diagnostic(ErrorCode.ERR_BadRecordBase, "A").WithLocation(2, 19)
                 );
+
+            Assert.Equal("class A", comp.GlobalNamespace.GetTypeMember("A")
+                .ToDisplayString(SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
         }
 
         [Fact]
-        public void Clone_10()
+        public void Clone_10_AmbiguousReverseOrder_UsedInWith()
         {
             var ilSource = @"
 .class public auto ansi beforefieldinit A
@@ -2432,6 +2455,9 @@ static void Main()
                 //         A x = new A() with { };
                 Diagnostic(ErrorCode.ERR_NoSingleCloneMethod, "new A()").WithArguments("A").WithLocation(6, 15)
                 );
+
+            Assert.Equal("class A", comp.GlobalNamespace.GetTypeMember("A")
+                .ToDisplayString(SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
         }
 
         [Fact]
@@ -2731,7 +2757,7 @@ public static void Main()
         }
 
         [Fact]
-        public void Clone_17()
+        public void Clone_17_NonOverridable()
         {
             var ilSource = @"
 .class public auto ansi beforefieldinit A
@@ -2822,10 +2848,13 @@ .maxstack 8
                 // public record B : A {
                 Diagnostic(ErrorCode.ERR_BadRecordBase, "A").WithLocation(2, 19)
                 );
+
+            Assert.Equal("class A", comp.GlobalNamespace.GetTypeMember("A")
+                .ToDisplayString(SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
         }
 
         [Fact]
-        public void Clone_18()
+        public void Clone_18_NonOverridable()
         {
             var ilSource = @"
 .class public auto ansi beforefieldinit A
@@ -2916,6 +2945,9 @@ .maxstack 8
                 // public record B : A {
                 Diagnostic(ErrorCode.ERR_BadRecordBase, "A").WithLocation(2, 19)
                 );
+
+            Assert.Equal("class A", comp.GlobalNamespace.GetTypeMember("A")
+                .ToDisplayString(SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
         }
 
         [Fact]
@@ -19120,6 +19152,19 @@ public static void Main()
                 );
         }
 
+        [Fact]
+        public void RecordLoadedInVisualBasicDisplaysAsRecord()
+        {
+            var src = @"
+public record A;
+";
+            var compRef = CreateCompilation(src).EmitToImageReference();
+            var vbComp = CreateVisualBasicCompilation("", referencedAssemblies: new[] { compRef });
+            var symbol = vbComp.GlobalNamespace.GetTypeMember("A");
+            Assert.Equal("record A",
+                SymbolDisplay.ToDisplayString(symbol, SymbolDisplayFormat.TestFormat.AddKindOptions(SymbolDisplayKindOptions.IncludeTypeKeyword)));
+        }
+
         [Fact]
         public void AnalyzerActions_01()
         {

src/Compilers/CSharp/Test/Symbol/SymbolDisplay/SymbolDisplayTests.cs

@@ -7584,5 +7584,26 @@ class B
                 method.ToDisplayParts(formatWithoutOptions),
                 "static void F4(nint[] x, A<nuint> y)");
         }
+
+        [Fact]
+        public void RecordDeclaration()
+        {
+            var text = @"
+record Person(string First, string Last);
+";
+            Func<NamespaceSymbol, Symbol> findSymbol = global => global.GetTypeMembers("Person").Single();
+
+            var format = new SymbolDisplayFormat(memberOptions: SymbolDisplayMemberOptions.IncludeType, kindOptions: SymbolDisplayKindOptions.IncludeTypeKeyword);
+
+            TestSymbolDescription(
+                text,
+                findSymbol,
+                format,
+                TestOptions.Regular.WithLanguageVersion(LanguageVersion.CSharp9),
+                "record Person",
+                SymbolDisplayPartKind.Keyword,
+                SymbolDisplayPartKind.Space,
+                SymbolDisplayPartKind.ClassName);
+        }
     }
 }

src/Compilers/Core/Portable/Symbols/SymbolEqualityComparer.cs

@@ -27,6 +27,7 @@ public sealed class SymbolEqualityComparer : IEqualityComparer<ISymbol?>
 
         // Internal only comparisons:
         internal readonly static SymbolEqualityComparer ConsiderEverything = new SymbolEqualityComparer(TypeCompareKind.ConsiderEverything);
+        internal readonly static SymbolEqualityComparer IgnoreAll = new SymbolEqualityComparer(TypeCompareKind.AllIgnoreOptions);
 
         internal TypeCompareKind CompareKind { get; }
 

src/EditorFeatures/CSharpTest/QuickInfo/SemanticQuickInfoSourceTests.cs

@@ -7036,5 +7036,35 @@ void Goo(object o)
     }
 }");
         }
+
+        [Fact, Trait(Traits.Feature, Traits.Features.QuickInfo)]
+        public async Task QuickInfoRecord()
+        {
+            await TestWithOptionsAsync(
+                Options.Regular.WithLanguageVersion(LanguageVersion.CSharp9),
+@"record Person(string First, string Last)
+{
+    void M($$Person p)
+    {
+    }
+}", MainDescription("record Person"));
+        }
+
+        [Fact, Trait(Traits.Feature, Traits.Features.QuickInfo)]
+        public async Task QuickInfoDerivedRecord()
+        {
+            await TestWithOptionsAsync(
+                Options.Regular.WithLanguageVersion(LanguageVersion.CSharp9),
+@"record Person(string First, string Last)
+{
+}
+record Student(string Id)
+{
+    void M($$Student p)
+    {
+    }
+}
+", MainDescription("record Student"));
+        }
     }
 }