Auto merge of #52830 - matthewjasper:bootstrap-prep, r=matthewjasper

[NLL] Fix some things for bootstrap

Some changes that are required when bootstrapping rustc with NLL enabled.

* Remove a bunch of unused `mut`s that aren't needed, but the existing lint doesn't catch.
* Rewrite a function call to satisfy NLL borrowck. Note that the borrow is two-phase, but gets activated immediately by an unsizing coercion.

cc #51823

1 files changed, 1 insertions, 1 deletions

diff --git a/src/librustc_save_analysis/lib.rs b/src/librustc_save_analysis/lib.rs
index a250d4a3598..761521c8807 100644
--- a/src/librustc_save_analysis/lib.rs
+++ b/src/librustc_save_analysis/lib.rs
@@ -423,7 +423,7 @@ impl<'l, 'tcx: 'l> SaveContext<'l, 'tcx> {
                             let mut qualname = String::from("<");
                             qualname.push_str(&self.tcx.hir.node_to_pretty_string(ty.id));
 
-                            let mut trait_id = self.tcx.trait_id_of_impl(impl_id);
+                            let trait_id = self.tcx.trait_id_of_impl(impl_id);
                             let mut decl_id = None;
                             let mut docs = String::new();
                             let mut attrs = vec![];