From 64b8b40cba8a13048bd4383acd69b4c91fc30aa1 Mon Sep 17 00:00:00 2001
From: Smit Patel <smitpatel@users.noreply.github.com>
Date: Tue, 31 Dec 2019 16:31:59 -0800
Subject: [PATCH] Metadata: Disallow backing field on indexer property

- Don't discover backing field for indexer property by convention
- Throw if trying to set a backing field for indexer property

Resolves #19448
---
 src/EFCore/Metadata/Internal/PropertyBase.cs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/EFCore/Metadata/Internal/PropertyBase.cs b/src/EFCore/Metadata/Internal/PropertyBase.cs
index 4c96274ac7b..8e3577aeda8 100644
--- a/src/EFCore/Metadata/Internal/PropertyBase.cs
+++ b/src/EFCore/Metadata/Internal/PropertyBase.cs
@@ -148,6 +148,14 @@ public virtual void SetField([CanBeNull] FieldInfo fieldInfo, ConfigurationSourc
                 return;
             }
 
+            if (PropertyInfo != null
+                && PropertyInfo.IsIndexerProperty()
+                && fieldInfo != null)
+            {
+                throw new InvalidOperationException(
+                    CoreStrings.BackingFieldOnIndexer(fieldInfo.GetSimpleMemberName(), DeclaringType.DisplayName(), Name));
+            }
+
             if (fieldInfo != null)
             {
                 IsCompatible(fieldInfo, ClrType, DeclaringType.ClrType, Name, shouldThrow: true);