From a5a67c4d0ca9339b97d6c2aaa6f88d4b8b67fb13 Mon Sep 17 00:00:00 2001
From: Shay Rojansky <roji@roji.org>
Date: Mon, 15 Aug 2022 16:07:48 +0200
Subject: [PATCH] Perform structural equality in ExpressionEqualityComparer

Fixes #28581
---
 .../Query/ExpressionEqualityComparer.cs       | 24 +++++++++++++++----
 .../Query/ExpressionEqualityComparerTest.cs   | 16 +++++++++++++
 2 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/src/EFCore/Query/ExpressionEqualityComparer.cs b/src/EFCore/Query/ExpressionEqualityComparer.cs
index bd8934fee4d..fd4bfd809ad 100644
--- a/src/EFCore/Query/ExpressionEqualityComparer.cs
+++ b/src/EFCore/Query/ExpressionEqualityComparer.cs
@@ -5,6 +5,8 @@
 // ReSharper disable ForCanBeConvertedToForeach
 // ReSharper disable LoopCanBeConvertedToQuery
 
+using System.Collections;
+
 namespace Microsoft.EntityFrameworkCore.Query;
 
 /// <summary>
@@ -64,10 +66,19 @@ public int GetHashCode(Expression obj)
                     break;
 
                 case ConstantExpression constantExpression:
-                    if (constantExpression.Value != null
-                        && !(constantExpression.Value is IQueryable))
+                    switch (constantExpression.Value)
                     {
-                        hash.Add(constantExpression.Value);
+                        case IQueryable:
+                        case null:
+                            break;
+
+                        case IStructuralEquatable structuralEquatable:
+                            hash.Add(structuralEquatable.GetHashCode(StructuralComparisons.StructuralEqualityComparer));
+                            break;
+
+                        default:
+                            hash.Add(constantExpression.Value);
+                            break;
                     }
 
                     break;
@@ -354,7 +365,12 @@ private bool CompareConditional(ConditionalExpression a, ConditionalExpression b
                 && Compare(a.IfFalse, b.IfFalse);
 
         private static bool CompareConstant(ConstantExpression a, ConstantExpression b)
-            => Equals(a.Value, b.Value);
+        {
+            var (v1, v2) = (a.Value, b.Value);
+
+            return Equals(v1, v2)
+                || (v1 is IStructuralEquatable array1 && array1.Equals(v2, StructuralComparisons.StructuralEqualityComparer));
+        }
 
         private bool CompareGoto(GotoExpression a, GotoExpression b)
             => a.Kind == b.Kind
diff --git a/test/EFCore.Tests/Query/ExpressionEqualityComparerTest.cs b/test/EFCore.Tests/Query/ExpressionEqualityComparerTest.cs
index 72f5ac01b21..7f61dfa7bdd 100644
--- a/test/EFCore.Tests/Query/ExpressionEqualityComparerTest.cs
+++ b/test/EFCore.Tests/Query/ExpressionEqualityComparerTest.cs
@@ -94,6 +94,22 @@ public void Index_expressions_are_compared_correctly()
         Assert.True(expressionComparer.Equals(e2, e3));
     }
 
+    [ConditionalFact]
+    public void Array_constant_expressions_are_compared_correctly()
+    {
+        var expressionComparer = ExpressionEqualityComparer.Instance;
+
+        var e1 = Expression.Constant(new[] { 1, 2, 3 });
+        var e2 = Expression.Constant(new[] { 1, 2, 3 });
+        var e3 = Expression.Constant(new[] { 1, 2, 4 });
+
+        Assert.True(expressionComparer.Equals(e1, e2));
+        Assert.False(expressionComparer.Equals(e1, e3));
+
+        Assert.Equal(expressionComparer.GetHashCode(e1), expressionComparer.GetHashCode(e2));
+        Assert.NotEqual(expressionComparer.GetHashCode(e1), expressionComparer.GetHashCode(e3));
+    }
+
     private class Node
     {
         [UsedImplicitly]