Polonius: emit initialization/move tracking facts

- var_starts_path
- parent
- initialized_at
- moved_out_at

This also switches to the intended emission of `var_drop_used` fact emission,
where that fact is always emitted on a drop-use of a variable, regardless of its
initialization status, as Polonius now handles that.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/librustc_mir/dataflow/move_paths/mod.rs b/src/librustc_mir/dataflow/move_paths/mod.rs
index e5a19572170..07b9b662a07 100644
--- a/src/librustc_mir/dataflow/move_paths/mod.rs
+++ b/src/librustc_mir/dataflow/move_paths/mod.rs
@@ -1,9 +1,10 @@
 use rustc::ty::{Ty, TyCtxt};
 use rustc::mir::*;
 use rustc::util::nodemap::FxHashMap;
-use rustc_data_structures::indexed_vec::{Idx, IndexVec};
+use rustc_data_structures::indexed_vec::{Idx, IndexVec, Enumerated};
 use smallvec::SmallVec;
 use syntax_pos::{Span};
+use core::slice::Iter;
 
 use std::fmt;
 use std::ops::{Index, IndexMut};
@@ -262,6 +263,12 @@ impl MovePathLookup {
     pub fn find_local(&self, local: Local) -> MovePathIndex {
         self.locals[local]
     }
+
+    /// An enumerated iterator of `local`s and their associated
+    /// `MovePathIndex`es.
+    pub fn iter_locals_enumerated(&self) -> Enumerated<Local, Iter<'_, MovePathIndex>> {
+        self.locals.iter_enumerated()
+    }
 }
 
 #[derive(Debug)]