[typer] fix some inconsistency in recursive comparison

src/core/tUnification.ml

@@ -478,7 +478,9 @@ let rec type_eq uctx a b =
 	| TType (t1,tl1), TType (t2,tl2) when (t1 == t2 || (param = EqCoreType && t1.t_path = t2.t_path)) && List.length tl1 = List.length tl2 ->
 		type_eq_params uctx a b tl1 tl2
 	| TType (t,tl) , _ when can_follow a ->
-		try_apply_params_rec t.t_params tl t.t_type (fun a -> type_eq uctx a b)
+		rec_stack eq_stack (a,b) (fast_eq_pair (a,b))
+			(fun() -> try_apply_params_rec t.t_params tl t.t_type (fun a -> type_eq uctx a b))
+			(fun l -> error (cannot_unify a b :: l))
 	| _ , TType (t,tl) when can_follow b ->
 		rec_stack eq_stack (a,b) (fast_eq_pair (a,b))
 			(fun() -> try_apply_params_rec t.t_params tl t.t_type (type_eq uctx a))
@@ -971,7 +973,8 @@ and unifies_to_field uctx a b ab tl (t,cf) =
 and unify_with_variance uctx f t1 t2 =
 	let t1 = follow_without_type t1 in
 	let t2 = follow_without_type t2 in
-	let unify_rec f = rec_stack_default variance_stack (t1,t2) (fast_eq_pair (t1,t2)) f () in
+	let fail () = error [cannot_unify t1 t2] in
+	let unify_rec f = rec_stack variance_stack (t1,t2) (fast_eq_pair (t1,t2)) f (fun _ -> fail()) in
 	let unify_nested t1 t2 = with_variance (get_nested_context uctx) f t1 t2 in
 	let unify_tls tl1 tl2 = List.iter2 unify_nested tl1 tl2 in
 	let get_this_type ab tl = follow_without_type (apply_params ab.a_params tl ab.a_this) in
@@ -991,7 +994,6 @@ and unify_with_variance uctx f t1 t2 =
 			) false
 		with Unify_error _ -> false
 	in
-	let fail () = error [cannot_unify t1 t2] in
 	match t1,t2 with
 	| TInst(c1,tl1),TInst(c2,tl2) when c1 == c2 ->
 		unify_tls tl1 tl2

tests/misc/compiler_loops/projects/Issue5189/compile-fail.hxml.stderr

@@ -1,3 +1,3 @@
 Main.hx:18: characters 9-29 : error: { c : Array<TT_A>, b : String, a : Int } has no field d
-Main.hx:18: characters 9-29 : ... have: { c: Array<{ c, b, a }> }
-Main.hx:18: characters 9-29 : ... want: { c: Array<TT_B> }
+Main.hx:18: characters 9-29 : ... have: { c: Array<TT_A> }
+Main.hx:18: characters 9-29 : ... want: { c: Array<TT_B> }

tests/misc/projects/Issue7227/compile-fail.hxml.stderr

@@ -1,3 +1,3 @@
-Main.hx:4: characters 9-81 : error: { url : String, method : String } should be String
-Main.hx:4: characters 9-81 : ... have: Generic<{ url: { url, method } }>
-Main.hx:4: characters 9-81 : ... want: Generic<{ url: String }>
+Main.hx:4: characters 9-81 : error: Struct should be String
+Main.hx:4: characters 9-81 : ... have: Generic<{ url: Struct }>
+Main.hx:4: characters 9-81 : ... want: Generic<{ url: String }>

tests/unit/src/unit/issues/Issue9761.hx

@@ -24,12 +24,15 @@ class Issue9761 extends Test {
     ((null: Array<YT<YT<Int>>>): Array<YT<XT<Int>>>);
     ((null: Array<YT<YT<Int>>>): Array<XT<XT<Int>>>);
 
+    ((null: X): Z);
+
     noAssert();
   }
 }
 
 private typedef X = {?x: X}
 private abstract Y(X) from X to X {}
+private abstract Z({?x: Z}) from X to X {}
 
 private typedef XT<T> = {?x: XT<T>, ?t: T}
 private abstract YT<T>(XT<T>) from XT<T> to XT<T> {}