GetCustomAttribute on inherited property throws IndexOutOfRangeException

[Steve887]

Description

I ran into an interesting situation trying to get Entity Framework working in my Xamarin application which I have narrowed down to what seems to be a bug internally. This may be the wrong place to post this as it may be better on the AspNetCore repo so I will move if required.

The bug occurs when you call GetCustomAttribute on an inherited property's GetMethod ReturnParameter. This results in an IndexOutOfRangeException. However, if the same code is called from a netcoreapp3.0 application it works as expected.

The exception occurs inside the internal InternalParamGetCustomAttributes method.

The setup for this reproduction comes from Entity Framework Core's NonNullableConventionBase which is called during Model setup, but Entity Framework is not required to reproduce.

var works = typeof(Blog).GetProperty("Url").GetMethod.ReturnParameter.GetCustomAttribute(typeof(AttributeUsageAttribute));
var worksAlso = typeof(Blog).GetProperty("Id").GetMethod.ReturnParameter.GetCustomAttribute(typeof(AttributeUsageAttribute));
var fails = typeof(Blog).GetProperty("Author").GetMethod.ReturnParameter.GetCustomAttribute(typeof(AttributeUsageAttribute));

public class Blog : BaseBlog
{
    public int Id { get; set; }
    public string Url { get; set; }
}

public class BaseBlog
{
    public string Author { get; set; }
}

Steps to Reproduce

1. Call GetMethod.ReturnParameter.GetCustomAttribute on an inherited property.

Expected Behavior

The Custom Attribute is returned, or null if it doesn't exist.

Actual Behavior

System.IndexOutOfRangeException

Basic Information

• Version with issue: 4.2.0.709249
• Last known good version: N/A
• IDE: Visual Studio 2019 16.3.5
• Platform Target Frameworks:
  • Android: 9.0
• Android Support Library Version: 28.0.0.1

Screenshots

Reproduction Link

IndexOutOfRangeException.zip Switch startup project between the Console app and Android app to see the issue.

[mindphaser]

Got this issue today when tried to migrate EF Core from 2.2.6 to 3.0.0 in Xamarin Forms project.

[Steve887]

@mindphaser That's how I came across the issue as well. It appears the EF Core team has worked around the issue in the latest preview build 3.1.0-preview2.19525.5 with this commit: https://github.com/aspnet/EntityFrameworkCore/commit/5fec0d085ef7e5702208c1169758f4f2d4e996d7#diff-920a9f983bb40645fe12f779d7f2d6df

The NonNullableConventionBase has been updated to do it's own filtering of Custom Attributes, rather than use the internal GetCustomAttribute implementation.

[Steve887]

@mindphaser I opened an issue in EFCore to track https://github.com/aspnet/EntityFrameworkCore/issues/18793

[MaximMikhisor]

Got this issue today when tried to migrate EF Core from 3.1.7 to 5.0.0-rc.1.20451.13 in Xamarin Forms project.