Rename variant AddrOfRegion of RegionVariableOrigin to BorrowRegion

because "Borrow" is the more idiomatic Rust term than "AddrOf".

compiler/rustc_hir_typeck/src/expr.rs

@@ -447,7 +447,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // this time with enough precision to check that the value
                 // whose address was taken can actually be made to live as long
                 // as it needs to live.
-                let region = self.next_region_var(infer::AddrOfRegion(expr.span));
+                let region = self.next_region_var(infer::BorrowRegion(expr.span));
                 Ty::new_ref(self.tcx, region, ty, mutbl)
             }
         }

compiler/rustc_infer/src/infer/mod.rs

@@ -458,8 +458,8 @@ pub enum RegionVariableOrigin {
     PatternRegion(Span),
 
     /// Regions created by `&` operator.
-    ///
-    AddrOfRegion(Span),
+    BorrowRegion(Span),
+
     /// Regions created as part of an autoref of a method receiver.
     Autoref(Span),
 
@@ -1741,7 +1741,7 @@ impl RegionVariableOrigin {
         match *self {
             MiscVariable(a)
             | PatternRegion(a)
-            | AddrOfRegion(a)
+            | BorrowRegion(a)
             | Autoref(a)
             | Coercion(a)
             | RegionParameterDefinition(a, ..)

compiler/rustc_trait_selection/src/error_reporting/infer/region.rs

@@ -1018,7 +1018,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         let var_description = match var_origin {
             infer::MiscVariable(_) => String::new(),
             infer::PatternRegion(_) => " for pattern".to_string(),
-            infer::AddrOfRegion(_) => " for borrow expression".to_string(),
+            infer::BorrowRegion(_) => " for borrow expression".to_string(),
             infer::Autoref(_) => " for autoref".to_string(),
             infer::Coercion(_) => " for automatic coercion".to_string(),
             infer::BoundRegion(_, br, infer::FnCall) => {