typing: special message when a single vararg is refused bu could be `...`-ed

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

diff --git a/src/semantize/typing.nit b/src/semantize/typing.nit
index e798ab2..df3b33a 100644 (file)
--- a/src/semantize/typing.nit
+++ b/src/semantize/typing.nit
@@ -453,12 +453,26 @@ private class TypeVisitor
                if vararg_rank >= 0 then
                        var paramtype = msignature.mparameters[vararg_rank].mtype
                        var first = args[vararg_rank]
-                       if vararg_decl == 0 and first isa AVarargExpr then
+                       if vararg_decl == 0 then
                                var mclass = get_mclass(node, "Array")
                                if mclass == null then return null # Forward error
                                var array_mtype = mclass.get_mtype([paramtype])
-                               self.visit_expr_subtype(first.n_expr, array_mtype)
-                               first.mtype  = first.n_expr.mtype
+                               if first isa AVarargExpr then
+                                       self.visit_expr_subtype(first.n_expr, array_mtype)
+                                       first.mtype  = first.n_expr.mtype
+                               else
+                                       # only one vararg, maybe `...` was forgot, so be gentle!
+                                       var t = visit_expr(first)
+                                       if t == null then return null # Forward error
+                                       if not is_subtype(t, paramtype) and is_subtype(t, array_mtype) then
+                                               # Not acceptable but could be a `...`
+                                               error(first, "Type Error: expected `{paramtype}`, got `{t}`. Is an ellipsis `...` missing on the argument?")
+                                               return null
+                                       end
+                                       # Standard valid vararg, finish the job
+                                       map.vararg_decl = 1
+                                       self.visit_expr_subtype(first, paramtype)
+                               end
                        else
                                map.vararg_decl = vararg_decl + 1
                                for i in [vararg_rank..vararg_rank+vararg_decl] do