From 52da88639e515dabe4927706025adf976d9cd2b7 Mon Sep 17 00:00:00 2001
From: ljedrz <ljedrz@gmail.com>
Date: Fri, 28 Sep 2018 17:38:02 +0200
Subject: [PATCH] rustc/infer: miscellaneous minor code improvements

---
 src/librustc/infer/error_reporting/mod.rs        | 8 ++++----
 src/librustc/infer/lexical_region_resolve/mod.rs | 4 +---
 src/librustc/infer/region_constraints/mod.rs     | 2 +-
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index a24eeb328427..6b9bb852a54f 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -406,10 +406,10 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             errors.clone()
         } else {
             errors
-                .iter()
-                .filter(|&e| !is_bound_failure(e))
-                .cloned()
-                .collect()
+            .iter()
+            .filter(|&e| !is_bound_failure(e))
+            .cloned()
+            .collect()
         };
 
         // sort the errors by span, for better error message stability.
diff --git a/src/librustc/infer/lexical_region_resolve/mod.rs b/src/librustc/infer/lexical_region_resolve/mod.rs
index a8fbfc3b64df..c2e75bedf0ae 100644
--- a/src/librustc/infer/lexical_region_resolve/mod.rs
+++ b/src/librustc/infer/lexical_region_resolve/mod.rs
@@ -147,9 +147,7 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {
     fn construct_var_data(&self, tcx: TyCtxt<'_, '_, 'tcx>) -> LexicalRegionResolutions<'tcx> {
         LexicalRegionResolutions {
             error_region: tcx.types.re_static,
-            values: (0..self.num_vars())
-                .map(|_| VarValue::Value(tcx.types.re_empty))
-                .collect(),
+            values: IndexVec::from_elem_n(VarValue::Value(tcx.types.re_empty), self.num_vars())
         }
     }
 
diff --git a/src/librustc/infer/region_constraints/mod.rs b/src/librustc/infer/region_constraints/mod.rs
index 1a79ca211283..f6192efb79ec 100644
--- a/src/librustc/infer/region_constraints/mod.rs
+++ b/src/librustc/infer/region_constraints/mod.rs
@@ -443,7 +443,7 @@ impl<'tcx> RegionConstraintCollector<'tcx> {
         assert!(self.undo_log[snapshot.length] == OpenSnapshot);
 
         if snapshot.length == 0 {
-            self.undo_log.truncate(0);
+            self.undo_log.clear();
         } else {
             (*self.undo_log)[snapshot.length] = CommitedSnapshot;
         }