diff --git a/benches/fibonacci.rs b/benches/fibonacci.rs
index ebb1b5fd0b18..9a68a69e800f 100644
--- a/benches/fibonacci.rs
+++ b/benches/fibonacci.rs
@@ -7,7 +7,7 @@ use crate::helpers::*;
 
 #[bench]
 fn fib(bencher: &mut Bencher) {
-    bencher.iter(|| fibonacci_helper::main())
+    bencher.iter(fibonacci_helper::main)
 }
 
 #[bench]
@@ -17,7 +17,7 @@ fn fib_miri(bencher: &mut Bencher) {
 
 #[bench]
 fn fib_iter(bencher: &mut Bencher) {
-    bencher.iter(|| fibonacci_helper_iterative::main())
+    bencher.iter(fibonacci_helper_iterative::main)
 }
 
 #[bench]
diff --git a/benches/smoke.rs b/benches/smoke.rs
index 9229e972d7f3..372cd0b22b7a 100644
--- a/benches/smoke.rs
+++ b/benches/smoke.rs
@@ -7,7 +7,7 @@ use crate::helpers::*;
 
 #[bench]
 fn noop(bencher: &mut Bencher) {
-    bencher.iter(|| smoke_helper::main())
+    bencher.iter(smoke_helper::main)
 }
 
 /*
diff --git a/src/diagnostics.rs b/src/diagnostics.rs
index 527ff032d670..ace521f1bed0 100644
--- a/src/diagnostics.rs
+++ b/src/diagnostics.rs
@@ -166,32 +166,32 @@ pub fn report_error<'tcx, 'mir>(
                     match history {
                         Some(TagHistory::Tagged {tag, created: (created_range, created_span), invalidated, protected }) => {
                             let msg = format!("{:?} was created by a retag at offsets {}", tag, HexRange(*created_range));
-                            helps.push((Some(created_span.clone()), msg));
+                            helps.push((Some(*created_span), msg));
                             if let Some((invalidated_range, invalidated_span)) = invalidated {
                                 let msg = format!("{:?} was later invalidated at offsets {}", tag, HexRange(*invalidated_range));
-                                helps.push((Some(invalidated_span.clone()), msg));
+                                helps.push((Some(*invalidated_span), msg));
                             }
                             if let Some((protecting_tag, protecting_tag_span, protection_span)) = protected {
-                                helps.push((Some(protecting_tag_span.clone()), format!("{:?} was protected due to {:?} which was created here", tag, protecting_tag)));
-                                helps.push((Some(protection_span.clone()), "this protector is live for this call".to_string()));
+                                helps.push((Some(*protecting_tag_span), format!("{:?} was protected due to {:?} which was created here", tag, protecting_tag)));
+                                helps.push((Some(*protection_span), "this protector is live for this call".to_string()));
                             }
                         }
                         Some(TagHistory::Untagged{ recently_created, recently_invalidated, matching_created, protected }) => {
                             if let Some((range, span)) = recently_created {
                                 let msg = format!("tag was most recently created at offsets {}", HexRange(*range));
-                                helps.push((Some(span.clone()), msg));
+                                helps.push((Some(*span), msg));
                             }
                             if let Some((range, span)) = recently_invalidated {
                                 let msg = format!("tag was later invalidated at offsets {}", HexRange(*range));
-                                helps.push((Some(span.clone()), msg));
+                                helps.push((Some(*span), msg));
                             }
                             if let Some((range, span)) = matching_created {
                                 let msg = format!("this tag was also created here at offsets {}", HexRange(*range));
-                                helps.push((Some(span.clone()), msg));
+                                helps.push((Some(*span), msg));
                             }
                             if let Some((protecting_tag, protecting_tag_span, protection_span)) = protected {
-                                helps.push((Some(protecting_tag_span.clone()), format!("{:?} was protected due to a tag which was created here", protecting_tag)));
-                                helps.push((Some(protection_span.clone()), "this protector is live for this call".to_string()));
+                                helps.push((Some(*protecting_tag_span), format!("{:?} was protected due to a tag which was created here", protecting_tag)));
+                                helps.push((Some(*protection_span), "this protector is live for this call".to_string()));
                             }
                         }
                         None => {}
diff --git a/src/eval.rs b/src/eval.rs
index 39fccb092433..a782dfa3fce1 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -491,6 +491,6 @@ mod tests {
         let cmd = String::from_utf16_lossy(&args_to_utf16_command_string(
             [r"C:\Program Files\", "arg1", "arg 2", "arg \" 3"].iter(),
         ));
-        assert_eq!(cmd.trim_end_matches("\0"), r#""C:\Program Files\" arg1 "arg 2" "arg \" 3""#);
+        assert_eq!(cmd.trim_end_matches('\0'), r#""C:\Program Files\" arg1 "arg 2" "arg \" 3""#);
     }
 }
diff --git a/src/helpers.rs b/src/helpers.rs
index 8339ecde121e..cb4c3c293e93 100644
--- a/src/helpers.rs
+++ b/src/helpers.rs
@@ -817,7 +817,7 @@ pub struct CurrentSpan<'a, 'mir, 'tcx> {
 
 impl<'a, 'mir, 'tcx> CurrentSpan<'a, 'mir, 'tcx> {
     pub fn get(&mut self) -> Span {
-        *self.span.get_or_insert_with(|| Self::current_span(&self.machine))
+        *self.span.get_or_insert_with(|| Self::current_span(self.machine))
     }
 
     #[inline(never)]
@@ -825,7 +825,7 @@ impl<'a, 'mir, 'tcx> CurrentSpan<'a, 'mir, 'tcx> {
         machine
             .threads
             .active_thread_stack()
-            .into_iter()
+            .iter()
             .rev()
             .find(|frame| {
                 let def_id = frame.instance.def_id();
diff --git a/src/shims/posix/fs.rs b/src/shims/posix/fs.rs
index 79539fd9c49e..d02410664bd4 100644
--- a/src/shims/posix/fs.rs
+++ b/src/shims/posix/fs.rs
@@ -304,7 +304,7 @@ pub struct FileHandler {
     handles: BTreeMap<i32, Box<dyn FileDescriptor>>,
 }
 
-impl<'tcx> FileHandler {
+impl FileHandler {
     pub(crate) fn new(mute_stdout_stderr: bool) -> FileHandler {
         let mut handles: BTreeMap<_, Box<dyn FileDescriptor>> = BTreeMap::new();
         handles.insert(0i32, Box::new(io::stdin()));
diff --git a/src/stacked_borrows.rs b/src/stacked_borrows.rs
index 6cb71f43118c..a19e30b113e3 100644
--- a/src/stacked_borrows.rs
+++ b/src/stacked_borrows.rs
@@ -684,9 +684,9 @@ impl Stacks {
         state: &GlobalState,
     ) -> InterpResult<'tcx> {
         trace!("deallocation with tag {:?}: {:?}, size {}", tag, alloc_id, range.size.bytes());
-        let mut state = state.borrow_mut();
+        let state = state.borrow();
         self.for_each_mut(range, |offset, stack, history| {
-            stack.dealloc(tag, (alloc_id, range, offset), &mut state, history)
+            stack.dealloc(tag, (alloc_id, range, offset), &state, history)
         })?;
         Ok(())
     }