[typer] revert static extension abstract cast change for now

see #5924
closes #7142

extra/CHANGES.txt

@@ -10,7 +10,6 @@ XXXX-XX-XX: 4.0.0-preview.4
 
 	all : implemented `for` loop unrolling (#3784)
 	all : metadata can now use `.`, e.g. `@:a.b`. This is represented as a string (#3959)
-	all : [breaking] disallow static extensions through abstract field casts (#5924)
 	all : [breaking] disallow static extensions on implicit `this` (#6036)
 	js : added externs for js.Date (#6855)
 	js : respect `-D source-map` flag to generate source maps in release builds

src/typing/fields.ml

@@ -250,7 +250,7 @@ let rec using_field ctx mode e i p =
 			begin match follow t with
 				| TFun((_,_,(TType({t_path = ["haxe";"macro"],"ExprOf"},[t0]) | t0)) :: args,r) ->
 					if is_dynamic && follow t0 != t_dynamic then raise Not_found;
-					Type.unify e.etype t0;
+					let e = AbstractCast.cast_or_unify_raise ctx t0 e p in
 					(* early constraints check is possible because e.etype has no monomorphs *)
 					List.iter2 (fun m (name,t) -> match follow t with
 						| TInst ({ cl_kind = KTypeParameter constr },_) when constr <> [] && not (has_mono m) ->

tests/unit/src/unit/issues/Issue2152.hx

@@ -0,0 +1,15 @@
+package unit.issues;
+
+using unit.issues.misc.Issue2152Class;
+
+private abstract MyInt(Int) {
+	public inline function new (x:Int) this = x;
+	@:to inline function toString ():String return "asString: " + this;
+}
+
+class Issue2152 extends Test {
+	function test() {
+		var z = new MyInt(1);
+		eq("asString: 1", z.passString());
+	}
+}