model: Add a class kind for class subsets

Signed-off-by: Jean-Christophe Beaupré <jcbrinfo@users.noreply.github.com>

diff --git a/src/model/model.nit b/src/model/model.nit
index 28303d0..58fe944 100644 (file)
--- a/src/model/model.nit
+++ b/src/model/model.nit
@@ -2595,10 +2595,16 @@ class MClassKind
        # Can a class of kind `self` specializes a class of kind `other`?
        fun can_specialize(other: MClassKind): Bool
        do
-               if other == interface_kind then return true # everybody can specialize interfaces
-               if self == interface_kind or self == enum_kind then
-                       # no other case for interfaces
+               if other == interface_kind then
+                       # everybody can specialize interfaces
+                       return true
+               else if self == interface_kind or self == enum_kind then
+                       # no other case for interfaces and enums
                        return false
+               else if self == subset_kind then
+                       # A subset may specialize anything, except another subset.
+                       # TODO: Allow sub-subsets once we can handle them.
+                       return other != subset_kind
                else if self == extern_kind then
                        # only compatible with themselves
                        return self == other
@@ -2619,6 +2625,8 @@ fun interface_kind: MClassKind do return once new MClassKind("interface", false,
 fun enum_kind: MClassKind do return once new MClassKind("enum", false, true, false)
 # The class kind `extern`
 fun extern_kind: MClassKind do return once new MClassKind("extern class", false, true, false)
+# The class kind `subset`
+fun subset_kind: MClassKind do return once new MClassKind("subset", true, false, false)
 
 # A standalone pre-constructed model used to test various model-related methods.
 #