Push AllowTwoPhase down to the HAIR level

For consistency, use AllowTwoPhase everywhere between the frontend and MIR.

8 files changed, 27 insertions, 22 deletions

diff --git a/src/librustc/ich/impls_ty.rs b/src/librustc/ich/impls_ty.rs
index 9a442e05299..89b8bfcd4ca 100644
--- a/src/librustc/ich/impls_ty.rs
+++ b/src/librustc/ich/impls_ty.rs
@@ -188,6 +188,10 @@ for ty::adjustment::Adjust<'gcx> {
 impl_stable_hash_for!(struct ty::adjustment::Adjustment<'tcx> { kind, target });
 impl_stable_hash_for!(struct ty::adjustment::OverloadedDeref<'tcx> { region, mutbl });
 impl_stable_hash_for!(struct ty::UpvarBorrow<'tcx> { kind, region });
+impl_stable_hash_for!(enum ty::adjustment::AllowTwoPhase {
+    Yes,
+    No
+});
 
 impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::adjustment::AutoBorrowMutability {
     fn hash_stable<W: StableHasherResult>(&self,
diff --git a/src/librustc/ty/adjustment.rs b/src/librustc/ty/adjustment.rs
index edd6d56759d..a0c31e8b509 100644
--- a/src/librustc/ty/adjustment.rs
+++ b/src/librustc/ty/adjustment.rs
@@ -131,6 +131,7 @@ impl<'a, 'gcx, 'tcx> OverloadedDeref<'tcx> {
 /// new code via two-phase borrows, so we try to limit where we create two-phase
 /// capable mutable borrows.
 /// See #49434 for tracking.
+#[derive(Copy, Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
 pub enum AllowTwoPhase {
     Yes,
     No
@@ -138,7 +139,7 @@ pub enum AllowTwoPhase {
 
 #[derive(Copy, Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
 pub enum AutoBorrowMutability {
-    Mutable { allow_two_phase_borrow: bool },
+    Mutable { allow_two_phase_borrow: AllowTwoPhase },
     Immutable,
 }
 
diff --git a/src/librustc_mir/hair/cx/expr.rs b/src/librustc_mir/hair/cx/expr.rs
index 62d1b43d625..5b373908480 100644
--- a/src/librustc_mir/hair/cx/expr.rs
+++ b/src/librustc_mir/hair/cx/expr.rs
@@ -662,9 +662,13 @@ trait ToBorrowKind { fn to_borrow_kind(&self) -> BorrowKind; }
 
 impl ToBorrowKind for AutoBorrowMutability {
     fn to_borrow_kind(&self) -> BorrowKind {
+        use rustc::ty::adjustment::AllowTwoPhase;
         match *self {
             AutoBorrowMutability::Mutable { allow_two_phase_borrow } =>
-                BorrowKind::Mut { allow_two_phase_borrow },
+                BorrowKind::Mut { allow_two_phase_borrow: match allow_two_phase_borrow {
+                    AllowTwoPhase::Yes => true,
+                    AllowTwoPhase::No => false
+                }},
             AutoBorrowMutability::Immutable =>
                 BorrowKind::Shared,
         }
diff --git a/src/librustc_typeck/check/callee.rs b/src/librustc_typeck/check/callee.rs
index 3d61ffe3933..b1fb0938698 100644
--- a/src/librustc_typeck/check/callee.rs
+++ b/src/librustc_typeck/check/callee.rs
@@ -16,7 +16,7 @@ use hir::def::Def;
 use hir::def_id::{DefId, LOCAL_CRATE};
 use rustc::{infer, traits};
 use rustc::ty::{self, TyCtxt, TypeFoldable, Ty};
-use rustc::ty::adjustment::{Adjustment, Adjust, AutoBorrow, AutoBorrowMutability};
+use rustc::ty::adjustment::{Adjustment, Adjust, AllowTwoPhase, AutoBorrow, AutoBorrowMutability};
 use syntax::abi;
 use syntax::symbol::Symbol;
 use syntax_pos::Span;
@@ -182,7 +182,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                     // For initial two-phase borrow
                                     // deployment, conservatively omit
                                     // overloaded function call ops.
-                                    allow_two_phase_borrow: false,
+                                    allow_two_phase_borrow: AllowTwoPhase::No,
                                 }
                             };
                             autoref = Some(Adjustment {
diff --git a/src/librustc_typeck/check/coercion.rs b/src/librustc_typeck/check/coercion.rs
index 8b4b4bab7c4..a956dd9a4ee 100644
--- a/src/librustc_typeck/check/coercion.rs
+++ b/src/librustc_typeck/check/coercion.rs
@@ -434,10 +434,7 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> {
         let mutbl = match mt_b.mutbl {
             hir::MutImmutable => AutoBorrowMutability::Immutable,
             hir::MutMutable => AutoBorrowMutability::Mutable {
-                allow_two_phase_borrow: match self.allow_two_phase {
-                    AllowTwoPhase::Yes => true,
-                    AllowTwoPhase::No => false
-                },
+                allow_two_phase_borrow: self.allow_two_phase,
             }
         };
         adjustments.push(Adjustment {
@@ -486,7 +483,7 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> {
                         // We don't allow two-phase borrows here, at least for initial
                         // implementation. If it happens that this coercion is a function argument,
                         // the reborrow in coerce_borrowed_ptr will pick it up.
-                        allow_two_phase_borrow: false,
+                        allow_two_phase_borrow: AllowTwoPhase::No,
                     }
                 };
                 Some((Adjustment {
diff --git a/src/librustc_typeck/check/method/confirm.rs b/src/librustc_typeck/check/method/confirm.rs
index b777ac30920..8a37c11f191 100644
--- a/src/librustc_typeck/check/method/confirm.rs
+++ b/src/librustc_typeck/check/method/confirm.rs
@@ -17,7 +17,7 @@ use rustc::ty::subst::Substs;
 use rustc::traits;
 use rustc::ty::{self, Ty};
 use rustc::ty::subst::Subst;
-use rustc::ty::adjustment::{Adjustment, Adjust, AutoBorrow, AutoBorrowMutability, OverloadedDeref};
+use rustc::ty::adjustment::{Adjustment, Adjust, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, OverloadedDeref};
 use rustc::ty::fold::TypeFoldable;
 use rustc::infer::{self, InferOk};
 use syntax_pos::Span;
@@ -170,7 +170,7 @@ impl<'a, 'gcx, 'tcx> ConfirmContext<'a, 'gcx, 'tcx> {
                 hir::MutMutable => AutoBorrowMutability::Mutable {
                     // Method call receivers are the primary use case
                     // for two-phase borrows.
-                    allow_two_phase_borrow: true,
+                    allow_two_phase_borrow: AllowTwoPhase::Yes,
                 }
             };
             adjustments.push(Adjustment {
@@ -544,7 +544,7 @@ impl<'a, 'gcx, 'tcx> ConfirmContext<'a, 'gcx, 'tcx> {
                             // For initial two-phase borrow
                             // deployment, conservatively omit
                             // overloaded operators.
-                            allow_two_phase_borrow: false,
+                            allow_two_phase_borrow: AllowTwoPhase::No,
                         }
                     };
                     adjustment.kind = Adjust::Borrow(AutoBorrow::Ref(region, mutbl));
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 0e1d3fdbb97..a377ff4d29d 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -2341,12 +2341,11 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                     let mutbl = match mt.mutbl {
                         hir::MutImmutable => AutoBorrowMutability::Immutable,
                         hir::MutMutable => AutoBorrowMutability::Mutable {
-                            // FIXME (#46747): arguably indexing is
-                            // "just another kind of call"; perhaps it
-                            // would be more consistent to allow
-                            // two-phase borrows for .index()
-                            // receivers here.
-                            allow_two_phase_borrow: false,
+                            // Indexing can be desugared to a method call,
+                            // so maybe we could use two-phase here.
+                            // See the documentation of AllowTwoPhase for why that's
+                            // not the case today.
+                            allow_two_phase_borrow: AllowTwoPhase::No,
                         }
                     };
                     adjustments.push(Adjustment {
@@ -3647,7 +3646,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                         // (It shouldn't actually matter for unary ops whether
                                         // we enable two-phase borrows or not, since a unary
                                         // op has no additional operands.)
-                                        allow_two_phase_borrow: false,
+                                        allow_two_phase_borrow: AllowTwoPhase::No,
                                     }
                                 };
                                 self.apply_adjustments(oprnd, vec![Adjustment {
diff --git a/src/librustc_typeck/check/op.rs b/src/librustc_typeck/check/op.rs
index eae692f4cda..a6fa3a6453f 100644
--- a/src/librustc_typeck/check/op.rs
+++ b/src/librustc_typeck/check/op.rs
@@ -14,7 +14,7 @@ use super::{FnCtxt, Needs};
 use super::method::MethodCallee;
 use rustc::ty::{self, Ty, TypeFoldable, TypeVariants};
 use rustc::ty::TypeVariants::{TyStr, TyRef, TyAdt};
-use rustc::ty::adjustment::{Adjustment, Adjust, AutoBorrow, AutoBorrowMutability};
+use rustc::ty::adjustment::{Adjustment, Adjust, AllowTwoPhase, AutoBorrow, AutoBorrowMutability};
 use rustc::infer::type_variable::TypeVariableOrigin;
 use errors;
 use syntax_pos::Span;
@@ -206,7 +206,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                             hir::MutMutable => AutoBorrowMutability::Mutable {
                                 // Allow two-phase borrows for binops in initial deployment
                                 // since they desugar to methods
-                                allow_two_phase_borrow: true,
+                                allow_two_phase_borrow: AllowTwoPhase::Yes,
                             }
                         };
                         let autoref = Adjustment {
@@ -223,7 +223,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                             hir::MutMutable => AutoBorrowMutability::Mutable {
                                 // Allow two-phase borrows for binops in initial deployment
                                 // since they desugar to methods
-                                allow_two_phase_borrow: true,
+                                allow_two_phase_borrow: AllowTwoPhase::Yes,
                             }
                         };
                         let autoref = Adjustment {