fix: stack overflow in comparer

Signed-off-by: Vincent Biret <vibiret@microsoft.com>

CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Fixed a stack overflow in the core generator caused by circular comparisons. [#5369](https://github.com/microsoft/kiota/issues/5369)
 - Fixed a bug where collection/array of primitive types members for union/intersection types would be ignored. [#5283](https://github.com/microsoft/kiota/issues/5283)
 - Fixed a when generating a plugin when only an operation is selected in the root node in the extension. [#5300](https://github.com/microsoft/kiota/issues/5300)
 

src/Kiota.Builder/Validation/OpenApiSchemaComparer.cs

@@ -27,7 +27,7 @@ internal class OpenApiSchemaComparer : IEqualityComparer<OpenApiSchema>
     /// <inheritdoc/>
     public bool Equals(OpenApiSchema? x, OpenApiSchema? y)
     {
-        return EqualsInternal(x, y);
+        return x == null && y == null || x != null && y != null && GetHashCode(x) == GetHashCode(y);
     }
     /// <inheritdoc/>
     public int GetHashCode([DisallowNull] OpenApiSchema obj)
@@ -37,25 +37,6 @@ internal class OpenApiSchemaComparer : IEqualityComparer<OpenApiSchema>
         return hash.ToHashCode();
     }
 
-    private bool EqualsInternal(OpenApiSchema? x, OpenApiSchema? y)
-    {
-        if (x is null || y is null) return object.Equals(x, y);
-        return x.Deprecated == y.Deprecated
-               && x.Nullable == y.Nullable
-               && x.AdditionalPropertiesAllowed == y.AdditionalPropertiesAllowed
-               && discriminatorComparer.Equals(x.Discriminator, y.Discriminator)
-               && string.Equals(x.Format, y.Format, StringComparison.OrdinalIgnoreCase)
-               && string.Equals(x.Type, y.Type, StringComparison.OrdinalIgnoreCase)
-               && string.Equals(x.Title, y.Title, StringComparison.Ordinal)
-               && openApiAnyComparer.Equals(x.Default, y.Default)
-               && EqualsInternal(x.AdditionalProperties, y.AdditionalProperties)
-               && EqualsInternal(x.Items, y.Items)
-               && Enumerable.SequenceEqual(x.Properties, y.Properties, schemaMapComparer)
-               && Enumerable.SequenceEqual(x.AnyOf, y.AnyOf, this)
-               && Enumerable.SequenceEqual(x.AllOf, y.AllOf, this)
-               && Enumerable.SequenceEqual(x.OneOf, y.OneOf, this);
-    }
-
     private void GetHashCodeInternal([DisallowNull] OpenApiSchema obj, HashSet<OpenApiSchema> visitedSchemas, ref HashCode hash)
     {
         if (obj is null) return;

tests/Kiota.Builder.Tests/Validation/OpenApiSchemaComparerTests.cs

@@ -1,5 +1,6 @@
 using System;
 using Kiota.Builder.Validation;
+using Microsoft.OpenApi.Models;
 using Xunit;
 
 namespace Kiota.Builder.Tests.Validation;
@@ -21,4 +22,21 @@ public class OpenApiSchemaComparerTests
     {
         Assert.True(_comparer.Equals(new(), new()));
     }
+    [Fact]
+    public void DoesNotStackOverFlowOnCircularReferencesForEquals()
+    {
+        var schema = new OpenApiSchema
+        {
+
+        };
+        schema.Properties.Add("test", schema);
+        schema.AnyOf.Add(schema);
+        var schema2 = new OpenApiSchema
+        {
+
+        };
+        schema2.Properties.Add("test", schema2);
+        schema2.AnyOf.Add(schema2);
+        Assert.True(_comparer.Equals(schema, schema2));
+    }
 }