+ // For from_iter, check if the type actualy implements FromIterator.
+ // If we know it does not, we don't need to warn.
+ if method_name.name == sym::from_iter {
+ if let Some(trait_def_id) = self.tcx.get_diagnostic_item(sym::FromIterator) {
+ if !self
+ .infcx
+ .type_implements_trait(
+ trait_def_id,
+ self_ty,
+ InternalSubsts::empty(),
+ self.param_env,
+ )
+ .may_apply()
+ {
+ return;
+ }
+ }
+ }
+