nitc/typing: isa uses intersect_types and diff_types

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

diff --git a/src/semantize/typing.nit b/src/semantize/typing.nit
index 7c1adf4..9813284 100644 (file)
--- a/src/semantize/typing.nit
+++ b/src/semantize/typing.nit
@@ -1788,9 +1788,16 @@ redef class AIsaExpr
                        #var to = if mtype != null then mtype.to_s else "invalid"
                        #debug("adapt {variable}: {from} -> {to}")
 
-                       # Do not adapt if there is no information gain (i.e. adapt to a supertype)
-                       if mtype == null or orig == null or not v.is_subtype(orig, mtype) then
-                               self.after_flow_context.when_true.set_var(v, variable, mtype)
+                       var thentype = v.intersect_types(self, orig, mtype)
+                       if thentype != orig then
+                               self.after_flow_context.when_true.set_var(v, variable, thentype)
+                               #debug "{variable}:{orig or else "?"} isa {mtype or else "?"} -> then {thentype or else "?"}"
+                       end
+
+                       var elsetype = v.diff_types(self, orig, mtype)
+                       if elsetype != orig then
+                               self.after_flow_context.when_false.set_var(v, variable, elsetype)
+                               #debug "{variable}:{orig or else "?"} isa {mtype or else "?"} -> else {elsetype or else "?"}"
                        end
                end