modelize_properties: check redef types in ATypePropdef

Because some programs (mnit) rely on unsound virtual type refinement,
some errors are displayed as warnings.

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/modelize_property.nit b/src/modelize_property.nit
index 96ec598..93f0e00 100644 (file)
--- a/src/modelize_property.nit
+++ b/src/modelize_property.nit
@@ -1003,25 +1003,40 @@ redef class ATypePropdef
 
                modelbuilder.check_visibility(n_type, bound, mpropdef)
 
-               # Fast case: the bound is not a formal type
-               if not bound isa MVirtualType then return
-
                var mclassdef = mpropdef.mclassdef
                var mmodule = mclassdef.mmodule
                var anchor = mclassdef.bound_mtype
 
-               # Slow case: progress on each resolution until: (i) we loop, or (ii) we found a non formal type
-               var seen = [self.mpropdef.mproperty.mvirtualtype]
-               loop
-                       if seen.has(bound) then
+               # Check circularity
+               if bound isa MVirtualType then
+                       # Slow case: progress on each resolution until: (i) we loop, or (ii) we found a non formal type
+                       var seen = [self.mpropdef.mproperty.mvirtualtype]
+                       loop
+                               if seen.has(bound) then
+                                       seen.add(bound)
+                                       modelbuilder.error(self, "Error: circularity of virtual type definition: {seen.join(" -> ")}")
+                                       return
+                               end
                                seen.add(bound)
-                               modelbuilder.error(self, "Error: circularity of virtual type definition: {seen.join(" -> ")}")
-                               return
+                               var next = bound.lookup_bound(mmodule, anchor)
+                               if not next isa MVirtualType then break
+                               bound = next
+                       end
+               end
+
+               # Check redefinitions
+               bound = mpropdef.bound.as(not null)
+               for p in mpropdef.mproperty.lookup_super_definitions(mmodule, anchor) do
+                       var supbound = p.bound.as(not null)
+                       if p.mclassdef.mclass == mclassdef.mclass then
+                               # Still a warning to pass existing bad code
+                               modelbuilder.warning(n_type, "Redef Error: a virtual type cannot be refined.")
+                               break
+                       end
+                       if not bound.is_subtype(mmodule, anchor, supbound) then
+                               modelbuilder.error(n_type, "Redef Error: Wrong bound type. Found {bound}, expected a subtype of {supbound}, as in {p}.")
+                               break
                        end
-                       seen.add(bound)
-                       var next = bound.lookup_bound(mmodule, anchor)
-                       if not next isa MVirtualType then break
-                       bound = next
                end
        end
 end