typing: new warning `useless-truism` to catch trainees.

[nit.git] / src / semantize / typing.nit

diff --git a/src/semantize/typing.nit b/src/semantize/typing.nit
index 8890ba9..3297d12 100644 (file)
--- a/src/semantize/typing.nit
+++ b/src/semantize/typing.nit
@@ -2017,6 +2017,10 @@ redef class AEqFormExpr
 
                if mtype == null or mtype2 == null then return
 
+               if mtype == v.type_bool(self) and (n_expr2 isa AFalseExpr or n_expr2 isa ATrueExpr) then
+                       v.modelbuilder.warning(self, "useless-truism", "Warning: useless comparison to a Bool literal.")
+               end
+
                if not mtype2 isa MNullType then return
 
                v.check_can_be_null(n_expr, mtype)