Crystal: Support the macro language inside enums

[ysbaddaden]

The following fails to compile with Syntax error in eval:4: unexpected token: ifdef:

enum Something
  VAL = 1

  ifdef darwin
    VAR = 2
  end
end

See https://play.crystal-lang.org/#/r/w5j

[asterite]

I can try to implement this. And maybe try to implement ifdef inside struct/union definitions (that doesn't work either).

[luislavena]

That will be excellent @asterite and will reduce a bit of duplication when defining structures/enums across POSIX platforms (I know, right now linux/darwin, but there are others) :smile:

[keplersj]

Is this still valid with #2710?

[jhass]

Kind of, we still can't have macros in enum's

enum Something
  VAL = 1

  {% if flag?(:darwin) %}
    VAR = 2
  {% end %}
  end
end

Syntax error in ./bug.cr:4: unexpected token: {%

  {% if flag?(:darwin) %}

Though I'm not sure whether that perhaps makes it a duplicate of #424

[keplersj]

I think that this issue is a dupe now.

[jhass]

well #424 is about macro calls.

[keplersj]

Okay, I see the difference now.

[asterite]

I can probably fix this for 0.18.0

[ysbaddaden]

Since it was impossible, not implementing ifdef in enum is fine, since it would just end up being removed in favor to macro calls with flags? a bit later.