[API Proposal]: SignatureTypeEncoder.TypedReference()

[jcouv]

Background and motivation

The roslyn compiler made two changes:

1. produce a warning instead of an error for pointer to managed type in unsafe context
2. consider System.TypedReference to be managed

As a result, it is possible to emit reference to this type in new contexts. For example in a pointer type.
The natural way to do it in Microsoft.Cci.MetadataWriter.SerializeTypeReference would be to call a SignatureTypeEncoder.TypedReference() method, but that method doesn't exist.
Note that such an API exists on ReturnTypeEncoder, LocalVariableTypeEncoder, and ParameterTypeEncoder already.

Relates to dotnet/roslyn#66328

API Proposal

namespace System.Reflection.Metadata.Ecma335;
public readonly struct SignatureTypeEncoder
{
    // additional method:
    public void TypedReference()
    {
        Builder.WriteByte((byte)SignatureTypeCode.TypedReference);
    }
}

API Usage

        private void SerializeTypeReference(SignatureTypeEncoder encoder, ITypeReference typeReference)
        {
            while (true)
            {
                if (module.IsPlatformType(typeReference, PlatformType.SystemTypedReference))
                {
                    encoder.TypedReference();
                    return;
                }
                ... handle other types and recursive scenarios
        }

Alternative Designs

It is possible to call Builder.WriteByte((byte)SignatureTypeCode.TypedReference); directly. That's the workaround used by the compiler for now.

Risks

No response

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Issue Details

---

Background and motivation

The roslyn compiler made two changes:

1. produce a warning instead of an error for pointer to managed type in unsafe context
2. consider System.TypedReference to be managed

As a result, it is possible to emit reference to this type in new contexts. For example in a pointer type.
The natural way to do it in Microsoft.Cci.MetadataWriter.SerializeTypeReference would be to call a SignatureTypeEncoder.TypedReference() method, but that method doesn't exist.
Note that such an API exists on ReturnTypeEncoder, LocalVariableTypeEncoder, and ParameterTypeEncoder already.

Relates to dotnet/roslyn#66328

API Proposal

namespace System.Reflection.Metadata.Ecma335;
public readonly struct SignatureTypeEncoder
{
    // additional method:
    public void TypedReference()
    {
        Builder.WriteByte((byte)SignatureTypeCode.TypedReference);
    }
}

API Usage

        private void SerializeTypeReference(SignatureTypeEncoder encoder, ITypeReference typeReference)
        {
            while (true)
            {
                if (module.IsPlatformType(typeReference, PlatformType.SystemTypedReference))
                {
                    encoder.TypedReference();
                    return;
                }
                ... handle other types and recursive scenarios
        }

Alternative Designs

It is possible to call Builder.WriteByte((byte)SignatureTypeCode.TypedReference); directly. That's the workaround used by the compiler for now.

Risks

No response

Author:	jcouv
Assignees:	-
Labels:	api-suggestion, area-System.Reflection.Metadata, untriaged
Milestone:	-

[steveharter]

Note that such an API exists on ReturnTypeEncoder, LocalVariableTypeEncoder, and ParameterTypeEncoder already.

Also exists on FieldTypeEncoder today.

[bartonjs]

Video

Looks good as proposed.

namespace System.Reflection.Metadata.Ecma335;
public readonly partial struct SignatureTypeEncoder
{
    public void TypedReference();
}