model: Make the `anchor` parameter of `MType::anchor_to` nullable

[nit.git] / src / model / model.nit

diff --git a/src/model/model.nit b/src/model/model.nit
index 35910d3..03d82b1 100644 (file)
--- a/src/model/model.nit
+++ b/src/model/model.nit
@@ -904,12 +904,13 @@ abstract class MType
        # because "redef type U: Y". Therefore, Map[T, U] is bound to
        # Map[B, Y]
        #
+       # REQUIRE: `self.need_anchor implies anchor != null`
        # ENSURE: `not self.need_anchor implies result == self`
        # ENSURE: `not result.need_anchor`
-       fun anchor_to(mmodule: MModule, anchor: MClassType): MType
+       fun anchor_to(mmodule: MModule, anchor: nullable MClassType): MType
        do
                if not need_anchor then return self
-               assert not anchor.need_anchor
+               assert anchor != null and not anchor.need_anchor
                # Just resolve to the anchor and clear all the virtual types
                var res = self.resolve_for(anchor, null, mmodule, true)
                assert not res.need_anchor
@@ -1220,7 +1221,7 @@ class MClassType
 
        redef fun need_anchor do return false
 
-       redef fun anchor_to(mmodule: MModule, anchor: MClassType): MClassType
+       redef fun anchor_to(mmodule, anchor): MClassType
        do
                return super.as(MClassType)
        end