diff --git a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
index 46e2a99a0d094..a0f8aabbe0e72 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
@@ -447,16 +447,20 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                                 // check if the RHS is from desugaring
                                 let opt_assignment_rhs_span =
                                     self.body.find_assignments(local).first().map(|&location| {
-                                        let stmt = &self.body[location.block].statements
-                                            [location.statement_index];
-                                        match stmt.kind {
-                                            mir::StatementKind::Assign(box (
-                                                _,
-                                                mir::Rvalue::Use(mir::Operand::Copy(place)),
-                                            )) => {
-                                                self.body.local_decls[place.local].source_info.span
-                                            }
-                                            _ => self.body.source_info(location).span,
+                                        if let Some(mir::Statement {
+                                            source_info: _,
+                                            kind:
+                                                mir::StatementKind::Assign(box (
+                                                    _,
+                                                    mir::Rvalue::Use(mir::Operand::Copy(place)),
+                                                )),
+                                        }) = self.body[location.block]
+                                            .statements
+                                            .get(location.statement_index)
+                                        {
+                                            self.body.local_decls[place.local].source_info.span
+                                        } else {
+                                            self.body.source_info(location).span
                                         }
                                     });
                                 match opt_assignment_rhs_span.and_then(|s| s.desugaring_kind()) {
diff --git a/compiler/rustc_codegen_gcc/src/abi.rs b/compiler/rustc_codegen_gcc/src/abi.rs
index ce428c589a478..2bbb199c89982 100644
--- a/compiler/rustc_codegen_gcc/src/abi.rs
+++ b/compiler/rustc_codegen_gcc/src/abi.rs
@@ -14,7 +14,7 @@ impl<'a, 'gcc, 'tcx> AbiBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
         // TODO(antoyo)
     }
 
-    fn get_param(&self, index: usize) -> Self::Value {
+    fn get_param(&mut self, index: usize) -> Self::Value {
         self.cx.current_func.borrow().expect("current func")
             .get_param(index as i32)
             .to_rvalue()
diff --git a/compiler/rustc_codegen_llvm/src/abi.rs b/compiler/rustc_codegen_llvm/src/abi.rs
index bedd3523d899e..07adfff0901a1 100644
--- a/compiler/rustc_codegen_llvm/src/abi.rs
+++ b/compiler/rustc_codegen_llvm/src/abi.rs
@@ -607,7 +607,7 @@ impl AbiBuilderMethods<'tcx> for Builder<'a, 'll, 'tcx> {
         fn_abi.apply_attrs_callsite(self, callsite)
     }
 
-    fn get_param(&self, index: usize) -> Self::Value {
+    fn get_param(&mut self, index: usize) -> Self::Value {
         llvm::get_param(self.llfn(), index as c_uint)
     }
 }
diff --git a/compiler/rustc_codegen_ssa/src/traits/abi.rs b/compiler/rustc_codegen_ssa/src/traits/abi.rs
index dd8495850bd54..a00d78daf4dcb 100644
--- a/compiler/rustc_codegen_ssa/src/traits/abi.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/abi.rs
@@ -4,5 +4,5 @@ use rustc_target::abi::call::FnAbi;
 
 pub trait AbiBuilderMethods<'tcx>: BackendTypes {
     fn apply_attrs_callsite(&mut self, fn_abi: &FnAbi<'tcx, Ty<'tcx>>, callsite: Self::Value);
-    fn get_param(&self, index: usize) -> Self::Value;
+    fn get_param(&mut self, index: usize) -> Self::Value;
 }
diff --git a/library/std/src/sys/hermit/mutex.rs b/library/std/src/sys/hermit/mutex.rs
index 691e7e07902d8..415cbba101c67 100644
--- a/library/std/src/sys/hermit/mutex.rs
+++ b/library/std/src/sys/hermit/mutex.rs
@@ -46,8 +46,17 @@ impl<T> Spinlock<T> {
     #[inline]
     fn obtain_lock(&self) {
         let ticket = self.queue.fetch_add(1, Ordering::SeqCst) + 1;
+        let mut counter: u16 = 0;
         while self.dequeue.load(Ordering::SeqCst) != ticket {
-            hint::spin_loop();
+            counter += 1;
+            if counter < 100 {
+                hint::spin_loop();
+            } else {
+                counter = 0;
+                unsafe {
+                    abi::yield_now();
+                }
+            }
         }
     }
 
diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index 0f3eb2ca07d23..bfad510695131 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -305,6 +305,10 @@ nav.sub {
 	overflow-y: scroll;
 }
 
+.rustdoc.source .sidebar {
+	overflow-y: auto;
+}
+
 /* Improve the scrollbar display on firefox */
 * {
 	scrollbar-width: initial;
diff --git a/src/test/ui/borrowck/issue-91206.rs b/src/test/ui/borrowck/issue-91206.rs
new file mode 100644
index 0000000000000..3b1fbf4b69902
--- /dev/null
+++ b/src/test/ui/borrowck/issue-91206.rs
@@ -0,0 +1,15 @@
+struct TestClient;
+
+impl TestClient {
+    fn get_inner_ref(&self) -> &Vec<usize> {
+        todo!()
+    }
+}
+
+fn main() {
+    let client = TestClient;
+    let inner = client.get_inner_ref();
+    //~^ HELP consider changing this to be a mutable reference
+    inner.clear();
+    //~^ ERROR cannot borrow `*inner` as mutable, as it is behind a `&` reference [E0596]
+}
diff --git a/src/test/ui/borrowck/issue-91206.stderr b/src/test/ui/borrowck/issue-91206.stderr
new file mode 100644
index 0000000000000..535d247452a59
--- /dev/null
+++ b/src/test/ui/borrowck/issue-91206.stderr
@@ -0,0 +1,12 @@
+error[E0596]: cannot borrow `*inner` as mutable, as it is behind a `&` reference
+  --> $DIR/issue-91206.rs:13:5
+   |
+LL |     let inner = client.get_inner_ref();
+   |         ----- help: consider changing this to be a mutable reference: `&mut Vec<usize>`
+LL |
+LL |     inner.clear();
+   |     ^^^^^^^^^^^^^ `inner` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0596`.