Auto merge of #63874 - spastorino:places-drive-by-cleanups, r=Centril

Places drive by cleanups

Small fixes of things meanwhile I was doing the box part of Place 2.0, based on @Centril reviews.

Author: bors

src/librustc/mir/mod.rs

@@ -1555,7 +1555,7 @@ pub struct Statement<'tcx> {
 #[cfg(target_arch = "x86_64")]
 static_assert_size!(Statement<'_>, 56);
 
-impl<'tcx> Statement<'tcx> {
+impl Statement<'_> {
     /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
     /// invalidating statement indices in `Location`s.
     pub fn make_nop(&mut self) {
@@ -1677,7 +1677,7 @@ pub struct InlineAsm<'tcx> {
     pub inputs: Box<[(Span, Operand<'tcx>)]>,
 }
 
-impl<'tcx> Debug for Statement<'tcx> {
+impl Debug for Statement<'_> {
     fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
         use self::StatementKind::*;
         match self.kind {
@@ -2047,7 +2047,7 @@ impl<'p, 'tcx> Iterator for ProjectionsIter<'p, 'tcx> {
 
 impl<'p, 'tcx> FusedIterator for ProjectionsIter<'p, 'tcx> {}
 
-impl<'tcx> Debug for Place<'tcx> {
+impl Debug for Place<'_> {
     fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
         self.iterate(|_place_base, place_projections| {
             // FIXME: remove this collect once we have migrated to slices

src/librustc/mir/visit.rs

@@ -724,10 +724,6 @@ macro_rules! make_mir_visitor {
                 }
 
                 match & $($mutability)? proj.elem {
-                    ProjectionElem::Deref => {
-                    }
-                    ProjectionElem::Subslice { from: _, to: _ } => {
-                    }
                     ProjectionElem::Field(_field, ty) => {
                         self.visit_ty(ty, TyContext::Location(location));
                     }
@@ -738,11 +734,12 @@ macro_rules! make_mir_visitor {
                             location
                         );
                     }
+                    ProjectionElem::Deref |
+                    ProjectionElem::Subslice { from: _, to: _ } |
                     ProjectionElem::ConstantIndex { offset: _,
                                                     min_length: _,
-                                                    from_end: _ } => {
-                    }
-                    ProjectionElem::Downcast(_name, _variant_index) => {
+                                                    from_end: _ } |
+                    ProjectionElem::Downcast(_, _) => {
                     }
                 }
             }

src/librustc_mir/borrow_check/prefixes.rs

@@ -136,7 +136,7 @@ impl<'cx, 'tcx> Iterator for Prefixes<'cx, 'tcx> {
                 }
                 PrefixSet::All => {
                     // all prefixes: just blindly enqueue the base
-                    // of the projection
+                    // of the projection.
                     self.next = Some(PlaceRef {
                         base: cursor.base,
                         projection: &proj.base,

src/librustc_mir/dataflow/move_paths/mod.rs

@@ -240,7 +240,7 @@ impl MovePathLookup {
     // alternative will *not* create a MovePath on the fly for an
     // unknown place, but will rather return the nearest available
     // parent.
-    pub fn find(&self, place_ref: PlaceRef<'cx, 'tcx>) -> LookupResult {
+    pub fn find(&self, place_ref: PlaceRef<'_, '_>) -> LookupResult {
         place_ref.iterate(|place_base, place_projection| {
             let mut result = match place_base {
                 PlaceBase::Local(local) => self.locals[*local],