From 3e42f981147108fa1a31971f21b35e3c30fc2058 Mon Sep 17 00:00:00 2001
From: AlekseyTs <alekseyt@microsoft.com>
Date: Tue, 24 Nov 2020 16:35:56 -0800
Subject: [PATCH 1/2] AddSynthesizedRecordMembersIfNecessary - avoid touching
 members that are known to have no effect on the outcome of the function.

This avoids unnecessary work and fixes #49286.
---
 .../Source/SourceMemberContainerSymbol.cs     |  8 +++
 .../Test/Symbol/Symbols/Source/RecordTests.cs | 66 +++++++++++++++++++
 2 files changed, 74 insertions(+)

diff --git a/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberContainerSymbol.cs b/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberContainerSymbol.cs
index 5be7d7f72f8f9..814183255f432 100644
--- a/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberContainerSymbol.cs
+++ b/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberContainerSymbol.cs
@@ -3034,6 +3034,14 @@ private void AddSynthesizedRecordMembersIfNecessary(MembersAndInitializersBuilde
             var members = ArrayBuilder<Symbol>.GetInstance(builder.NonTypeNonIndexerMembers.Count + 1);
             foreach (var member in builder.NonTypeNonIndexerMembers)
             {
+                switch(member)
+                {
+                    case FieldSymbol:
+                    case EventSymbol:
+                    case MethodSymbol { MethodKind: not (MethodKind.Ordinary or MethodKind.Constructor) }:
+                        continue;
+                }
+
                 if (!memberSignatures.ContainsKey(member))
                 {
                     memberSignatures.Add(member, member);
diff --git a/src/Compilers/CSharp/Test/Symbol/Symbols/Source/RecordTests.cs b/src/Compilers/CSharp/Test/Symbol/Symbols/Source/RecordTests.cs
index 3c9bfe700fdba..81534c2b48141 100644
--- a/src/Compilers/CSharp/Test/Symbol/Symbols/Source/RecordTests.cs
+++ b/src/Compilers/CSharp/Test/Symbol/Symbols/Source/RecordTests.cs
@@ -1566,5 +1566,71 @@ .maxstack  1
   IL_001b:  ret
 }");
         }
+
+        [Fact]
+        [WorkItem(49286, "https://github.com/dotnet/roslyn/issues/49286")]
+        public void RecordWithEventImplicitlyImplementingAnInterface()
+        {
+            var src = @"
+using System;
+
+public interface I1
+{
+    event Action E1;
+}
+
+public record R1 : I1
+{
+    public event Action E1 {  add { } remove { } }
+}
+";
+
+            var comp = CreateCompilation(src);
+            comp.VerifyEmitDiagnostics();
+        }
+
+        [Fact]
+        [WorkItem(49286, "https://github.com/dotnet/roslyn/issues/49286")]
+        public void RecordWithPropertyImplicitlyImplementingAnInterface()
+        {
+            var src = @"
+using System;
+
+public interface I1
+{
+    Action P1 { get; set; }
+}
+
+public record R1 : I1
+{
+    public Action P1 {  get; set; }
+}
+";
+
+            var comp = CreateCompilation(src);
+            comp.VerifyEmitDiagnostics();
+        }
+
+        [Fact]
+        [WorkItem(49286, "https://github.com/dotnet/roslyn/issues/49286")]
+        public void RecordWithMethodImplicitlyImplementingAnInterface()
+        {
+            var src = @"
+using System;
+
+public interface I1
+{
+    Action M1();
+}
+
+public record R1 : I1
+{
+    public Action M1() => throw null;
+}
+";
+
+            var comp = CreateCompilation(src);
+            comp.VerifyEmitDiagnostics();
+        }
     }
 }

From 736bddaff88748a4e284258bdb380bb9b70220d5 Mon Sep 17 00:00:00 2001
From: AlekseyTs <alekseyt@microsoft.com>
Date: Tue, 24 Nov 2020 17:15:39 -0800
Subject: [PATCH 2/2] Fix formatting

---
 .../Portable/Symbols/Source/SourceMemberContainerSymbol.cs      | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberContainerSymbol.cs b/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberContainerSymbol.cs
index 814183255f432..9d22f94f23437 100644
--- a/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberContainerSymbol.cs
+++ b/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberContainerSymbol.cs
@@ -3034,7 +3034,7 @@ private void AddSynthesizedRecordMembersIfNecessary(MembersAndInitializersBuilde
             var members = ArrayBuilder<Symbol>.GetInstance(builder.NonTypeNonIndexerMembers.Count + 1);
             foreach (var member in builder.NonTypeNonIndexerMembers)
             {
-                switch(member)
+                switch (member)
                 {
                     case FieldSymbol:
                     case EventSymbol: