remove redundant imports

detects redundant imports that can be eliminated.

for #117772 :

In order to facilitate review and modification, split the checking code and
removing redundant imports code into two PR.

compiler/rustc_mir_transform/src/coverage/query.rs

@@ -2,9 +2,9 @@ use super::*;
 
 use rustc_data_structures::captures::Captures;
 use rustc_middle::mir::coverage::*;
-use rustc_middle::mir::{Body, Coverage, CoverageIdsInfo};
+use rustc_middle::mir::{Body, CoverageIdsInfo};
 use rustc_middle::query::Providers;
-use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::ty::{self};
 
 /// A `query` provider for retrieving coverage information injected into MIR.
 pub(crate) fn provide(providers: &mut Providers) {