typing: accept `null` as a receiver for some methods of Object

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

diff --git a/src/semantize/typing.nit b/src/semantize/typing.nit
index 932256f..e283b43 100644 (file)
--- a/src/semantize/typing.nit
+++ b/src/semantize/typing.nit
@@ -266,8 +266,13 @@ private class TypeVisitor
 
                #debug("recv: {recvtype} (aka {unsafe_type})")
                if recvtype isa MNullType then
-                       self.error(node, "Error: Method '{name}' call on 'null'.")
-                       return null
+                       # `null` only accepts some methods of object.
+                       if name == "==" or name == "!=" then
+                               unsafe_type = mmodule.object_type.as_nullable
+                       else
+                               self.error(node, "Error: Method '{name}' call on 'null'.")
+                               return null
+                       end
                end
 
                var mproperty = self.try_get_mproperty_by_name2(node, unsafe_type, name)