[API Proposal]: aot export api stdcall,UnmanagedCallersOnly for vb6

[xiaoyaocode163]

Background and motivation

HOW TO EXPORT API IN VB.NET? LIKE:DotNetRuntimeDebugHeader

c# can export stdcall api by UnmanagedCallersOnly,but vb.net can't do this,how can you fix?
or i can use
public function add_export_stdcall(a as long,b as long) as long
return a+b
end function

aot will auto set add_export_stdcall to export as :add

`public static class MyFunctions
{
[UnmanagedCallersOnly(EntryPoint = "Add")]
public static int Add(int a, int b)
{
return a + b;
}

[UnmanagedCallersOnly(EntryPoint = "PrintString")]
public static void PrintString(IntPtr str)
{
    Console.WriteLine(Marshal.PtrToStringAnsi(str));
}

[UnmanagedCallersOnly(EntryPoint = "GetSystemInfoWrite")]
public static void GetSystemInfo()
{
    Console.WriteLine($"ProcessorCount: {Environment.ProcessorCount}");
    Console.WriteLine($"MachineName: {Environment.MachineName}");
}

}`

API Proposal

namespace System.Collections.Generic;

public class MyFancyCollection<T> : IEnumerable<T>
{
    public void Fancy(T item);
}

API Usage

// Fancy the value
var c = new MyFancyCollection<int>();
c.Fancy(42);

// Getting the values out
foreach (var v in c)
    Console.WriteLine(v);

Alternative Designs

No response

Risks

No response

[ghost]

Tagging subscribers to this area: @agocke, @MichalStrehovsky, @jkotas
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Background and motivation

HOW TO EXPORT API IN VB.NET? LIKE:DotNetRuntimeDebugHeader

c# can export stdcall api by UnmanagedCallersOnly,but vb.net can't do this,how can you fix?
or i can use
public function add_export_stdcall(a as long,b as long) as long
return a+b
end function

aot will auto set add_export_stdcall to export as :add

`public static class MyFunctions
{
[UnmanagedCallersOnly(EntryPoint = "Add")]
public static int Add(int a, int b)
{
return a + b;
}

[UnmanagedCallersOnly(EntryPoint = "PrintString")]
public static void PrintString(IntPtr str)
{
    Console.WriteLine(Marshal.PtrToStringAnsi(str));
}

[UnmanagedCallersOnly(EntryPoint = "GetSystemInfoWrite")]
public static void GetSystemInfo()
{
    Console.WriteLine($"ProcessorCount: {Environment.ProcessorCount}");
    Console.WriteLine($"MachineName: {Environment.MachineName}");
}

}`

API Proposal

namespace System.Collections.Generic;

public class MyFancyCollection<T> : IEnumerable<T>
{
    public void Fancy(T item);
}

API Usage

// Fancy the value
var c = new MyFancyCollection<int>();
c.Fancy(42);

// Getting the values out
foreach (var v in c)
    Console.WriteLine(v);

Alternative Designs

No response

Risks

No response

Author:	xiaoyaocode163
Assignees:	-
Labels:	api-suggestion, untriaged, area-NativeAOT-coreclr
Milestone:	-

[am11]

I assume this is because UnmanagedCallersOnly is not CLS complaint: #40461. VB compiler gives error BC37316: 'UnmanagedCallersOnly' attribute is not supported :(

Bad workaround: manually inject attribute in IL using reflection etc.
Better workaround: use C# project to expose your API with <ProjectReference Include="path\to\your.vbproj" /> in csproj.

[jkotas]

It is by design that Visual Basic cannot do everything that C# can do. .NET language strategy explains our approach in more detail.

use C# project to expose your API

Yes, this is the right solution.

[MichalStrehovsky]

Cc @dotnet/interop-contrib - UnamangedCallersOnlyAttribute cannot be used with VB due to the non-CLS compliant constructor