entproto: enum values with special characters are not supported

[jamslinger]

Ent allows enum Values with special characters as long as they are valid Go identifiers. For NamedValues anything is allowed. In entproto the keys of the configured enum mapping must match the values of the field.Enum but if those contain special characters, the protobuf and gRPC service generation currently fails.

• The issue is present in the latest release.
• I have searched the issues of this repository and believe that this is not a duplicate.

Current Behavior 😯

Protobuf message and gRPC service generation fails for field.Enum with values containing special characters:

func (Logo) Fields() []ent.Field {
	return []ent.Field{
		field.Enum("mimeType").
			NamedValues(
				"JPEG", "image/jpeg",
				"PNG", "image/png",
				"SVG", "image/svg+xml").
			Annotations(
				entproto.Field(2), 
				entproto.Enum(map[string]int32{
					"image/jpeg":    1,
					"image/png":     2,
					"image/svg+xml": 3,
				}),
			),
		field.Bytes("content").Annotations(entproto.Field(3)),
	}
}

func (Logo) Annotations() []schema.Annotation {
	return []schema.Annotation{
		entproto.Message(),
		entproto.Service(),
	}
}

Expected Behavior 🤔

Message and service generation should succeed while preserving the Proto Style Guide for value names:

message Logo {
  int64 id = 1;

  MimeType mimeType = 2;

  bytes content = 3;

  enum MimeType {
    MIME_TYPE_UNSPECIFIED = 0;

    MIME_TYPE_IMAGE_JPEG = 1;

    MIME_TYPE_IMAGE_PNG = 2;

    MIME_TYPE_IMAGE_SVG_XML = 3;
  }
}

Steps to Reproduce 🕹

Steps:

1. Create an ent schema with field.Enum
2. Define enum Values or NamedValues containing special characters ([^a-zA-Z0-9_]+)
3. Add entproto.Field and entproto.Enum field annotations
4. Add entproto annotation to generate protobuf message and gRPC service
5. Attempt message and service generation

Your Environment 🌎

I'm using the

Tech	Version
Go	1.19.0
Ent	0.12.0
Database	SQLite