finish fixing PR#5322

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@11158 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

Changes

@@ -20,8 +20,7 @@ Standard library:
       with user-provided hash functions.
 
 Bug Fixes:
-- type abbreviations expanding to a universal type variable were not working
-  correctly during unification
+- PR#5322: type abbreviations expanding to a universal type variable
 
 OCaml 3.12.1:
 ----------------------

testsuite/tests/typing-poly-bugs/Makefile

@@ -0,0 +1,3 @@
+BASEDIR=../..
+include $(BASEDIR)/makefiles/Makefile.okbad
+include $(BASEDIR)/makefiles/Makefile.common

testsuite/tests/typing-poly-bugs/pr5322_ok.ml

@@ -0,0 +1,7 @@
+type 'par t = 'par
+module M : sig val x : <m : 'a. 'a> end =
+  struct let x : <m : 'a. 'a t> = Obj.magic () end
+
+let ident v = v
+class alias = object method alias : 'a . 'a t -> 'a = ident end
+

typing/ctype.ml

@@ -2060,9 +2060,7 @@ let rec moregen inst_nongen type_pairs env t1 t2 =
 
   try
     match (t1.desc, t2.desc) with
-      (Tunivar, Tunivar) ->
-        unify_univar t1 t2 !univar_pairs
-    | (Tvar, _) when may_instantiate inst_nongen t1 ->
+      (Tvar, _) when may_instantiate inst_nongen t1 ->
         moregen_occur env t1.level t2;
         occur env t1 t2;
         link_type t1 t2
@@ -2091,7 +2089,8 @@ let rec moregen inst_nongen type_pairs env t1 t2 =
           | (Tconstr (p1, tl1, _), Tconstr (p2, tl2, _))
                 when Path.same p1 p2 ->
               moregen_list inst_nongen type_pairs env tl1 tl2
-          | Tpackage (p1, n1, tl1), Tpackage (p2, n2, tl2) when Path.same p1 p2 && n1 = n2 ->
+          | (Tpackage (p1, n1, tl1), Tpackage (p2, n2, tl2))
+            when Path.same p1 p2 && n1 = n2 ->
               moregen_list inst_nongen type_pairs env tl1 tl2
           | (Tvariant row1, Tvariant row2) ->
               moregen_row inst_nongen type_pairs env row1 row2
@@ -2106,6 +2105,8 @@ let rec moregen inst_nongen type_pairs env t1 t2 =
           | (Tpoly (t1, tl1), Tpoly (t2, tl2)) ->
               enter_poly env univar_pairs t1 tl1 t2 tl2
                 (moregen inst_nongen type_pairs env)
+          | (Tunivar, Tunivar) ->
+              unify_univar t1' t2' !univar_pairs
           | (_, _) ->
               raise (Unify [])
         end