documentation fix

Author: dingxiangfei2009

compiler/rustc_middle/src/middle/region.rs

@@ -283,23 +283,27 @@ pub struct ScopeTree {
     /// To see that this method works, consider:
     ///
     /// Let `D` be our binding/temporary and `U` be our other HIR node, with
-    /// `HIR-postorder(U) < HIR-postorder(D)` (in our example, U would be
-    /// the yield and D would be one of the calls). Let's show that
-    /// `D` is storage-dead at `U`.
+    /// `HIR-postorder(U) < HIR-postorder(D)`. Suppose, as in our example,
+    /// U is the yield and D is one of the calls.
+    /// Let's show that `D` is storage-dead at `U`.
     ///
     /// Remember that storage-live/storage-dead refers to the state of
     /// the *storage*, and does not consider moves/drop flags.
     ///
     /// Then:
+    ///
     ///     1. From the ordering guarantee of HIR visitors (see
     ///     `rustc_hir::intravisit`), `D` does not dominate `U`.
+    ///
     ///     2. Therefore, `D` is *potentially* storage-dead at `U` (because
     ///     we might visit `U` without ever getting to `D`).
+    ///
     ///     3. However, we guarantee that at each HIR point, each
     ///     binding/temporary is always either always storage-live
     ///     or always storage-dead. This is what is being guaranteed
     ///     by `terminating_scopes` including all blocks where the
     ///     count of executions is not guaranteed.
+    ///
     ///     4. By `2.` and `3.`, `D` is *statically* storage-dead at `U`,
     ///     QED.
     ///

compiler/rustc_mir_build/src/build/matches/simplify.rs

@@ -28,8 +28,9 @@ use std::mem;
 impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Simplify a candidate so that all match pairs require a test.
     ///
-    /// This method will also split a candidate where the only match-pair is an
-    /// or-pattern into multiple candidates. This is so that
+    /// This method will also split a candidate, in which the only
+    /// match-pair is an or-pattern, into multiple candidates.
+    /// This is so that
     ///
     /// match x {
     ///     0 | 1 => { ... },