enum abstract syntax

[Simn]

Allows enum abstract instead of @:enum abstract and deprecates the latter. We still use @:enum internally for now, so most of the changes here are in .hx files.

I'll follow my usual policy of "merge if nobody complains".

[Justinfront]

if p <> null_pos then ctx.com.warning "`@:enum abstract` is deprecated in favor of `enum abstract`" p;

would this require #if haxe3 code in libraries or will both be supported for awhile?

[Simn]

It's a warning, so it's gonna work either way. I think we have a way to disable warnings now as well. @RealyUniqueName should know more.

[ncannasse]

Regarding deprecation warnings: we have several of them for Haxe 4.0 , I wonder how we should handle them. For instance compile with -D haxe3-syntax would disable all these warnings. Whereas compiling with -D haxe4-syntax would turn them into errors.

[ncannasse]

Question: enum abstract or abstract enum ?

[Simn]

Conceptually, it's still an abstract and comes with all abstract features. So enum abstract is correct.

[Gama11]

I agree that a define to disable Haxe 4 specific warnings would be helpful, all the warnings can get annoying, especially if you can't fix them because they're in third-party libs.

I think enum abstract makes sense because enum in this case is like a modifier for abstract.

[R32]

I think it's possible to use the enum directly.

enum Foo { // when "var" it's must be "enum abstract"
    var A = 1; 
}

enum Bar {// normal enum
    A;    
}

[back2dos]

@R32 In theory it's not a bad idea. In practice there are multiple differences to consider:

1. abstracts have more features (implicit casts, operator overloading, methods)
2. abstracts don't exist at compile time: Type.typeof(Bar.A) is TEnum(Bar) and Type.typeof(Foo.A) is TInt. Corollary: enums unify with EnumValue, abstracts don't.

[Simn]

I'll go ahead and merge this, then disable the deprecation warning for now. We can re-enable it once we know how to deal with the Haxe 4 transition in general.

[Simn]

It just occurred to me that we can check for the presence of the hx3compat define. This way we can keep some behavior if -lib hx3compat is in place.