More options for @(Import) and C# 10 global usings?

[jonathanpeppers]

Context: dotnet/android#6118

We have an issue in .NET 6 Android applications, where every Android app has a method like:

protected override void OnCreate(Bundle? savedInstanceState)

We don't want to include <Import Include="Android.OS" />, because Android.OS.Environment would conflict with System.Environment. Developers would likely use System.Environment, so we don't want to cause an issue there.

So our plan is to add the global using:

global using Bundle = global::Android.OS.Bundle;

Unfortunately, it's not possible to use the @(Import) item group to do this, because it always prefixes global:::

sdk/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.GenerateImplicitNamespaceImports.targets

Line 46 in 86946f5

<_ImportFileLine Include="global using global::%(_UniqueImport.Identity)%3B"/>

What we did for now is generate our own C# file for this one line.

This seems OK, but is it worth adding some support to @(Import) so you could do something like:

<Import Include="Bundle = global::Android.OS.Bundle" />

Maybe the dotnet/sdk could simply skip the global:: prefix if the string contains it?

[jonathanpeppers]

/cc @JunTaoLuo

[JunTaoLuo]

@DamianEdwards who's the area owner. I don't think this is a feature we're looking to add at the moment since it's explicitly only designed for namespace imports and not aliases.

[DamianEdwards]

@JunTaoLuo actually I listed that as one of the things to do as part of the feedback in #19521. As part of renaming <Import /> to <Using /> and <DisableImplicitNamespaceImports> to <ImplicitUsings> it becomes more natural and event expected to support this.

[DamianEdwards]

Closing this as the request feature is covered in #19521. Once that's done you'll be able to do:

<Using Include="Android.OS.Bundle" Alias="Bundle" />