Update with response to feedback

src/librustc/ty/mod.rs

@@ -2227,7 +2227,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         queries::impl_trait_ref::get(self, DUMMY_SP, id)
     }
 
-    /// Returns true if the impl is positive and is for a triat which contains
+    /// Returns true if the impl is positive and is for a trait which contains
     /// no items
     pub fn impl_always_allowed_to_overlap(self, def_id: DefId) -> bool {
         self.trait_impl_polarity(def_id) == hir::ImplPolarity::Positive

src/test/run-pass/overlap-permitted-for-marker-traits.rs

@@ -19,5 +19,6 @@ fn foo<T: MyMarker>(t: T) -> T {
 
 fn main() {
     assert_eq!(1, foo(1));
+    assert_eq!(2.0, foo(2.0));
     assert_eq!(vec![1], foo(vec![1]));
 }