CallingConvention gap in ILGenerator.EmitCalli

[mellinoe]

Based on this stackoverflow submission.

It seems like there is a bit of a feature gap in the current interface for ILGenerator. .NET Core has a EmitCalli method, but the calling conventions it supports do not line up exactly with the ones exposed from the .NET Framework: https://msdn.microsoft.com/en-us/library/d81ee808(v=vs.110).aspx

We should understand if this is a meaningful gap, or if the use cases for the .NET Framework version can still be covered by the new version.

We may already be considering adding this functionality back as part of our bigger API compat push.

cc: @atsushikan

For future clarification:

ILGenerator on Core is missing the overload of EmitCalli that takes a System.Runtime.InteropServices.CallingConvention enum (the unmanaged calling convention enum that includes CDecl.)

[karelz]

@atsushikan @DnlHarvey please update top post with proposal if it is ready.

Does not need an api review as this proposal is simply about restoring an overload that already exists on the full framework:

public virtual void EmitCalli(
OpCode opcode,
CallingConvention unmanagedCallConv,
Type returnType,
Type[] parameterTypes
)

[karelz]

@atsushikan is it just matter of exposing existing functionality, or what is involved in the work? (the "next step & complexity" comment ;-))

[karelz]

Also, unassigning you as you don't plan to work on it now ...

The overload and its underlying support was physically removed from CoreClr so it'll have to be exhumed from the desktop source. Estimate: light to medium complexity.

[Cronan]

I'm interested in having a go at this, it's a major blocking issue for
pythonnet/pythonnet#96

Any advice other than "read the contrib dox"?

[jkotas]

Needs to be exposed from the contracts: https://github.com/dotnet/corefx/tree/master/src/System.Reflection.Emit.ILGeneration

[Cronan]

I noticed this - I can do it as well, if you like, I’ve got the code open as it is

[jkotas]

@Cronan Yes, that would be great. Thanks!

[Cronan]

I'm slightly confused about where exactly the change should be made.
The screen grab below is from my corefx checkout of master

Also, this is in the interface:
coreclr\src\mscorlib\shared\System\Runtime\InteropServices\CallingConvention.cs

I'm not sure how to reference it correctly from corefx.