Weird implicit cast hangs the compiler in pattern matching.

[back2dos]

class Test {
  static function main() {
    final v = new Vector([1, 2]);
    switch v {
      case [1,2]: true;
      case _: false;
    }
  }
}

abstract Vector<T>(Array<T>) {
  public inline function new(a)
    this = a;
  @:from static function fromVector<T, R:T>(v:Vector<R>):Vector<T>
    return cast v;
}

Compiler seems to be stuck in a loop. From haxetink/tink_pure#18

[RealyUniqueName]

It loops in these lines of function pattern:

haxe/src/typing/matcher.ml

Lines 403 to 405 in 0dc581c

	| TAbstract(a,tl) ->
	begin match TyperBase.get_abstract_froms a tl with
	| [t2] -> pattern t2

TyperBase.get_abstract_froms a tl returns Vector<?> every time and that goes into pattern call again.

[Simn]

I have fixed the hang because hanging sucks, but I'm a bit confused about this code checking for abstract @:from in the first place. Where would that casting code even be inserted...