clean up issue-18088 (operator from supertrait)

Author: omskscream

tests/ui/issues/issue-18088.rs

@@ -0,0 +1,13 @@
+//@ check-pass
+
+//! Tests that operators from supertrait are available directly on `self` for an inheritor trait.
+//!
+//! # Context
+//! Original issue: https://github.com/rust-lang/rust/issues/18088
+
+pub trait Indexable<T>: std::ops::Index<usize, Output = T> {
+    fn index2(&self, i: usize) -> &T {
+        &self[i]
+    }
+}
+fn main() {}