Fix DataGrid native aot crash when sorting.

[dameng324]

What does the pull request do?

When sorting datagrid with a non string type field, the application will crash as no metadata of Comparer<int>. This PR fix it.

Fixed: #14059

What is the current behavior?

• When user does not provide the ViewModel meta data (by [DynamicDependcy] or Rd.xml etc), the application does not crash when sorting int field. but the sort function is broken.

• When user provide the ViewModel meta data (by [DynamicDependcy] or Rd.xml etc), the application will crash when sorting int field.

What is the updated/expected behavior with this PR?

• When user does not provide the ViewModel meta data (by [DynamicDependcy] or Rd.xml etc), the application will behave same as before when sorting.

• When user provide the ViewModel meta data (by [DynamicDependcy] or Rd.xml etc), the application will work normal when sorting int/int?/Enum/Enum? and other type which implements IComparable interface when using aot. Other type which does not implements IComparable should not crash, only does nothing when sorting.

How was the solution implemented (if it's not obvious)?

Old solution:

return (typeof(Comparer<>).MakeGenericType(type).GetProperty("Default")).GetValue(null, null) as IComparer;

My solution:

#if NET6_0_OR_GREATER
if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>) && type.GetGenericArguments()[0].IsAssignableTo(typeof(IComparable)))
    return Comparer<object>.Create((x, y) => 
    {
        if (x == null)
            return y == null ? 0 : -1;
        else
            return (x as IComparable)!.CompareTo(y);
    });
else if (type.IsAssignableTo(typeof(IComparable)))
    return Comparer<object>.Create((x, y) => (x as IComparable)!.CompareTo(y));
else
    return Comparer<object>.Create((x, y) => 0);
#else
    return (typeof(Comparer<>).MakeGenericType(type).GetProperty("Default")).GetValue(null, null) as IComparer;
#endif

Checklist

• Added unit tests (if possible)?
• Added XML documentation to any related classes?
• Consider submitting a PR to https://github.com/AvaloniaUI/avalonia-docs with user documentation

Breaking changes

Obsoletions / Deprecations

Fixed issues

Fixed: #14059

[avaloniaui-bot]

You can test this PR using the following package version. 11.3.999-cibuild0052600-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[cla-avalonia]

• All contributors have signed the CLA.

[dameng324]

@cla-avalonia agree

[avaloniaui-bot]

You can test this PR using the following package version. 11.3.999-cibuild0052602-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[maxkatz6]

On NET6_0_OR_GREATER you can check for this property whether reflection is supported: https://learn.microsoft.com/en-us/dotnet/api/system.runtime.compilerservices.runtimefeature.isdynamiccodesupported?view=net-8.0

On AOT builds IsDynamicCodeSupported returns false, and this fallback would make sense there.

[maxkatz6]

This way we also won't regress any application that relies on this reflection sorting right now.

[dameng324]

Nice suggestion. Done.

[dameng324]

User can not use sort feature when they does not provide metadata of the type when using aot, Can we do better to avoid user make this kind of mistake? such as add some aot compile warning, or add [DynamicallyAccessedMembersAttribute] or [DynamicDependency] to somewhere? @maxkatz6 do you have any idea on it?

[avaloniaui-bot]

You can test this PR using the following package version. 11.3.999-cibuild0052607-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[maxkatz6]

@dameng324 we could generate DynamicDependency based on DataGridColumn.SortMemberPath type. See #14085. As an extra attribute on https://github.com/AvaloniaUI/Avalonia/blob/master/src/Avalonia.Controls.DataGrid/DataGridColumn.cs#L1124C23-L1124C37

Ideally, AOT apps would utilize CustomSortComparer instead https://github.com/AvaloniaUI/Avalonia/blob/master/src/Avalonia.Controls.DataGrid/DataGridColumn.cs#L1142, which would reduce reflection usage quite a bit.

Other than this, any refactorings of DataGrid control are not planned.

[dameng324]

@maxkatz6 Thanks for the info.

solving this by xaml compiler will be really nice.

[dameng324]

@maxkatz6 I wonder when will it be published? I didn't see this in the latest 11.2 rc version.