syntax: no isa/as warning for double nullable formal type

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

diff --git a/src/syntax/typing.nit b/src/syntax/typing.nit
index d070119..3cc50b2 100644 (file)
--- a/src/syntax/typing.nit
+++ b/src/syntax/typing.nit
@@ -1579,7 +1579,13 @@ special PExpr
                else if etype < ttype then
                        v.warning(self, "Warning: Expression is already a {ttype} since it is a {etype}.")
                else if etype.is_nullable and etype.as_notnull == ttype then
-                       if self isa AIsaExpr then
+                       if ttype isa MMTypeFormal and ttype.bound.is_nullable then
+                               # No warning in this case since with
+                               #   type T: nullable A
+                               #   var x: nullable T
+                               # 'x.as(not null)' != 'x.as(T)'
+                               # 'x != null' != 'x isa T'
+                       else if self isa AIsaExpr then
                                v.warning(self, "Warning: Prefer '!= null'.")
                        else
                                v.warning(self, "Warning: Prefer '.as(not null)'.")