Auto merge of #51248 - fabric-and-ink:newtype_index_debrujin, r=nikomatsakis

Declare DebruijnIndex via newtype_index macro

Part of #49887

Declare `DebruijnIndex` via the `newtype_index` macro.

Author: bors

src/librustc/infer/error_reporting/nice_region_error/find_anon_type.rs

@@ -77,7 +77,7 @@ impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> {
             tcx: self.tcx,
             bound_region: *br,
             found_type: None,
-            current_index: ty::DebruijnIndex::INNERMOST,
+            current_index: ty::INNERMOST,
         };
         nested_visitor.visit_ty(arg);
         nested_visitor.found_type

src/librustc/infer/higher_ranked/mod.rs

@@ -417,8 +417,7 @@ impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
         {
             for (a_br, a_r) in a_map {
                 if *a_r == r {
-                    return infcx.tcx.mk_region(ty::ReLateBound(ty::DebruijnIndex::INNERMOST,
-                                                               *a_br));
+                    return infcx.tcx.mk_region(ty::ReLateBound(ty::INNERMOST, *a_br));
                 }
             }
             span_bug!(
@@ -735,7 +734,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                     // trait checking, and all of the skolemized regions
                     // appear inside predicates, which always have
                     // binders, so this assert is satisfied.
-                    assert!(current_depth > ty::DebruijnIndex::INNERMOST);
+                    assert!(current_depth > ty::INNERMOST);
 
                     // since leak-check passed, this skolemized region
                     // should only have incoming edges from variables

src/librustc/middle/resolve_lifetime.rs

@@ -98,7 +98,7 @@ impl Region {
     }
 
     fn late(hir_map: &Map, def: &hir::LifetimeDef) -> (hir::LifetimeName, Region) {
-        let depth = ty::DebruijnIndex::INNERMOST;
+        let depth = ty::INNERMOST;
         let def_id = hir_map.local_def_id(def.lifetime.id);
         let origin = LifetimeDefOrigin::from_is_in_band(def.in_band);
         debug!(
@@ -114,7 +114,7 @@ impl Region {
     fn late_anon(index: &Cell<u32>) -> Region {
         let i = index.get();
         index.set(i + 1);
-        let depth = ty::DebruijnIndex::INNERMOST;
+        let depth = ty::INNERMOST;
         Region::LateBoundAnon(depth, i)
     }
 
@@ -1870,7 +1870,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
             .map(|(i, input)| {
                 let mut gather = GatherLifetimes {
                     map: self.map,
-                    outer_index: ty::DebruijnIndex::INNERMOST,
+                    outer_index: ty::INNERMOST,
                     have_bound_regions: false,
                     lifetimes: FxHashSet(),
                 };

src/librustc/ty/flags.rs

@@ -24,7 +24,7 @@ impl FlagComputation {
     fn new() -> FlagComputation {
         FlagComputation {
             flags: TypeFlags::empty(),
-            outer_exclusive_binder: ty::DebruijnIndex::INNERMOST,
+            outer_exclusive_binder: ty::INNERMOST,
         }
     }
 
@@ -60,7 +60,7 @@ impl FlagComputation {
         // a region binder, so subtract one from the region depth
         // within when adding the depth to `self`.
         let outer_exclusive_binder = computation.outer_exclusive_binder;
-        if outer_exclusive_binder > ty::DebruijnIndex::INNERMOST {
+        if outer_exclusive_binder > ty::INNERMOST {
             self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1));
         } else {
             // otherwise, this binder captures nothing

src/librustc/ty/fold.rs

@@ -65,7 +65,7 @@ pub trait TypeFoldable<'tcx>: fmt::Debug + Clone {
 
     /// True if `self` has any late-bound regions that are either
     /// bound by `binder` or bound by some binder outside of `binder`.
-    /// If `binder` is `ty::DebruijnIndex::INNERMOST`, this indicates whether
+    /// If `binder` is `ty::INNERMOST`, this indicates whether
     /// there are any late-bound regions that appear free.
     fn has_regions_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool {
         self.visit_with(&mut HasEscapingRegionsVisitor { outer_index: binder })
@@ -78,7 +78,7 @@ pub trait TypeFoldable<'tcx>: fmt::Debug + Clone {
     }
 
     fn has_escaping_regions(&self) -> bool {
-        self.has_regions_bound_at_or_above(ty::DebruijnIndex::INNERMOST)
+        self.has_regions_bound_at_or_above(ty::INNERMOST)
     }
 
     fn has_type_flags(&self, flags: TypeFlags) -> bool {
@@ -246,7 +246,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
               T: TypeFoldable<'tcx>,
     {
         value.visit_with(&mut RegionVisitor {
-            outer_index: ty::DebruijnIndex::INNERMOST,
+            outer_index: ty::INNERMOST,
             callback
         });
 
@@ -260,7 +260,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             /// ^          ^          ^     ^
             /// |          |          |     | here, would be shifted in 1
             /// |          |          | here, would be shifted in 2
-            /// |          | here, would be INNTERMOST shifted in by 1
+            /// |          | here, would be INNERMOST shifted in by 1
             /// | here, initially, binder would be INNERMOST
             /// ```
             ///
@@ -333,7 +333,7 @@ impl<'a, 'gcx, 'tcx> RegionFolder<'a, 'gcx, 'tcx> {
         RegionFolder {
             tcx,
             skipped_regions,
-            current_index: ty::DebruijnIndex::INNERMOST,
+            current_index: ty::INNERMOST,
             fold_region_fn,
         }
     }
@@ -495,7 +495,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         let mut counter = 0;
         Binder::bind(self.replace_late_bound_regions(sig, |_| {
             counter += 1;
-            self.mk_region(ty::ReLateBound(ty::DebruijnIndex::INNERMOST, ty::BrAnon(counter)))
+            self.mk_region(ty::ReLateBound(ty::INNERMOST, ty::BrAnon(counter)))
         }).0)
     }
 }
@@ -507,7 +507,7 @@ impl<'a, 'gcx, 'tcx> RegionReplacer<'a, 'gcx, 'tcx> {
     {
         RegionReplacer {
             tcx,
-            current_index: ty::DebruijnIndex::INNERMOST,
+            current_index: ty::INNERMOST,
             fld_r,
             map: BTreeMap::default()
         }
@@ -542,7 +542,7 @@ impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for RegionReplacer<'a, 'gcx, 'tcx> {
                     // that region should always use the INNERMOST
                     // debruijn index. Then we adjust it to the
                     // correct depth.
-                    assert_eq!(debruijn1, ty::DebruijnIndex::INNERMOST);
+                    assert_eq!(debruijn1, ty::INNERMOST);
                     self.tcx.mk_region(ty::ReLateBound(debruijn, br))
                 } else {
                     region
@@ -701,7 +701,7 @@ struct LateBoundRegionsCollector {
 impl LateBoundRegionsCollector {
     fn new(just_constrained: bool) -> Self {
         LateBoundRegionsCollector {
-            current_index: ty::DebruijnIndex::INNERMOST,
+            current_index: ty::INNERMOST,
             regions: FxHashSet(),
             just_constrained,
         }

src/librustc/ty/mod.rs

@@ -60,7 +60,7 @@ use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult,
 
 use hir;
 
-pub use self::sty::{Binder, CanonicalVar, DebruijnIndex};
+pub use self::sty::{Binder, CanonicalVar, DebruijnIndex, INNERMOST};
 pub use self::sty::{FnSig, GenSig, PolyFnSig, PolyGenSig};
 pub use self::sty::{InferTy, ParamTy, ProjectionTy, ExistentialPredicate};
 pub use self::sty::{ClosureSubsts, GeneratorSubsts, UpvarSubsts, TypeAndMut};

src/librustc/ty/sty.rs

@@ -1023,12 +1023,11 @@ impl<'a, 'gcx, 'tcx> ParamTy {
 /// is the outer fn.
 ///
 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
-#[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, Copy, PartialOrd, Ord)]
-pub struct DebruijnIndex {
-    /// We maintain the invariant that this is never 0. So 1 indicates
-    /// the innermost binder.
-    index: u32,
-}
+newtype_index!(DebruijnIndex
+    {
+        DEBUG_FORMAT = "DebruijnIndex({})",
+        const INNERMOST = 0,
+    });
 
 pub type Region<'tcx> = &'tcx RegionKind;
 
@@ -1261,8 +1260,6 @@ impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
 }
 
 impl DebruijnIndex {
-    pub const INNERMOST: DebruijnIndex = DebruijnIndex { index: 0 };
-
     /// Returns the resulting index when this value is moved into
     /// `amount` number of new binders. So e.g. if you had
     ///
@@ -1275,7 +1272,7 @@ impl DebruijnIndex {
     /// you would need to shift the index for `'a` into 1 new binder.
     #[must_use]
     pub const fn shifted_in(self, amount: u32) -> DebruijnIndex {
-        DebruijnIndex { index: self.index + amount }
+        DebruijnIndex(self.0 + amount)
     }
 
     /// Update this index in place by shifting it "in" through
@@ -1288,7 +1285,7 @@ impl DebruijnIndex {
     /// `amount` number of new binders.
     #[must_use]
     pub const fn shifted_out(self, amount: u32) -> DebruijnIndex {
-        DebruijnIndex { index: self.index - amount }
+        DebruijnIndex(self.0 - amount)
     }
 
     /// Update in place by shifting out from `amount` binders.
@@ -1317,13 +1314,11 @@ impl DebruijnIndex {
     /// bound by one of the binders we are shifting out of, that is an
     /// error (and should fail an assertion failure).
     pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
-        self.shifted_out(to_binder.index - Self::INNERMOST.index)
+        self.shifted_out((to_binder.0 - INNERMOST.0) as u32)
     }
 }
 
-impl_stable_hash_for!(struct DebruijnIndex {
-    index
-});
+impl_stable_hash_for!(tuple_struct DebruijnIndex { index });
 
 /// Region utilities
 impl RegionKind {

src/librustc/ty/util.rs

@@ -555,7 +555,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                           -> Option<ty::Binder<Ty<'tcx>>>
     {
         let closure_ty = self.mk_closure(closure_def_id, closure_substs);
-        let env_region = ty::ReLateBound(ty::DebruijnIndex::INNERMOST, ty::BrEnv);
+        let env_region = ty::ReLateBound(ty::INNERMOST, ty::BrEnv);
         let closure_kind_ty = closure_substs.closure_kind_ty(closure_def_id, self);
         let closure_kind = closure_kind_ty.to_opt_closure_kind()?;
         let env_ty = match closure_kind {

src/librustc/util/ppaux.rs

@@ -527,7 +527,7 @@ impl PrintContext {
                     ty::BrNamed(tcx.hir.local_def_id(CRATE_NODE_ID), name)
                 }
             };
-            tcx.mk_region(ty::ReLateBound(ty::DebruijnIndex::INNERMOST, br))
+            tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br))
         }).0;
         start_or_continue(f, "", "> ")?;
 

src/librustc_codegen_llvm/common.rs

@@ -425,7 +425,7 @@ pub fn ty_fn_sig<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
             let tcx = cx.tcx;
             let sig = substs.poly_sig(def_id, cx.tcx);
 
-            let env_region = ty::ReLateBound(ty::DebruijnIndex::INNERMOST, ty::BrEnv);
+            let env_region = ty::ReLateBound(ty::INNERMOST, ty::BrEnv);
             let env_ty = tcx.mk_mut_ref(tcx.mk_region(env_region), ty);
 
             sig.map_bound(|sig| {

src/librustc_driver/test.rs

@@ -183,7 +183,7 @@ fn test_env_with_pool<F>(
     });
 }
 
-const D1: ty::DebruijnIndex = ty::DebruijnIndex::INNERMOST;
+const D1: ty::DebruijnIndex = ty::INNERMOST;
 const D2: ty::DebruijnIndex = D1.shifted_in(1);
 
 impl<'a, 'gcx, 'tcx> Env<'a, 'gcx, 'tcx> {

src/librustc_typeck/check/closure.rs

@@ -463,7 +463,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         // Create a `PolyFnSig`. Note the oddity that late bound
         // regions appearing free in `expected_sig` are now bound up
         // in this binder we are creating.
-        assert!(!expected_sig.sig.has_regions_bound_above(ty::DebruijnIndex::INNERMOST));
+        assert!(!expected_sig.sig.has_regions_bound_above(ty::INNERMOST));
         let bound_sig = ty::Binder::bind(self.tcx.mk_fn_sig(
             expected_sig.sig.inputs().iter().cloned(),
             expected_sig.sig.output(),

src/librustc_typeck/check/intrinsic.rs

@@ -119,7 +119,7 @@ pub fn check_intrinsic_type<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
             "pref_align_of" | "min_align_of" => (1, Vec::new(), tcx.types.usize),
             "size_of_val" |  "min_align_of_val" => {
                 (1, vec![
-                    tcx.mk_imm_ref(tcx.mk_region(ty::ReLateBound(ty::DebruijnIndex::INNERMOST,
+                    tcx.mk_imm_ref(tcx.mk_region(ty::ReLateBound(ty::INNERMOST,
                                                                   ty::BrAnon(0))),
                                     param(0))
                  ], tcx.types.usize)
@@ -298,7 +298,7 @@ pub fn check_intrinsic_type<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
             "unlikely" => (0, vec![tcx.types.bool], tcx.types.bool),
 
             "discriminant_value" => (1, vec![
-                    tcx.mk_imm_ref(tcx.mk_region(ty::ReLateBound(ty::DebruijnIndex::INNERMOST,
+                    tcx.mk_imm_ref(tcx.mk_region(ty::ReLateBound(ty::INNERMOST,
                                                                   ty::BrAnon(0))),
                                    param(0))], tcx.types.u64),
 

src/librustc_typeck/collect.rs

@@ -736,7 +736,7 @@ fn has_late_bound_regions<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                         -> Option<Span> {
         let mut visitor = LateBoundRegionsDetector {
             tcx,
-            outer_index: ty::DebruijnIndex::INNERMOST,
+            outer_index: ty::INNERMOST,
             has_late_bound_regions: None,
         };
         for lifetime in generics.lifetimes() {

src/test/ui/nll/closure-requirements/escape-argument-callee.stderr

@@ -18,7 +18,7 @@ LL |         let mut closure = expect_sig(|p, y| *p = y);
    |
    = note: defining type: DefId(0/1:9 ~ escape_argument_callee[317d]::test[0]::{{closure}}[0]) with closure substs [
                i16,
-               for<'r, 's, 't0> extern "rust-call" fn((&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) mut &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) i32, &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 't0)) i32))
+               for<'r, 's, 't0> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 'r)) mut &ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 's)) i32, &ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 't0)) i32))
            ]
 
 note: No external requirements

src/test/ui/nll/closure-requirements/escape-argument.stderr

@@ -6,7 +6,7 @@ LL |         let mut closure = expect_sig(|p, y| *p = y);
    |
    = note: defining type: DefId(0/1:9 ~ escape_argument[317d]::test[0]::{{closure}}[0]) with closure substs [
                i16,
-               for<'r, 's> extern "rust-call" fn((&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) mut &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) i32, &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) i32))
+               for<'r, 's> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 'r)) mut &ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 's)) i32, &ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 's)) i32))
            ]
 
 note: No external requirements

src/test/ui/nll/closure-requirements/propagate-approximated-fail-no-postdom.stderr

@@ -24,7 +24,7 @@ LL | |         },
    |
    = note: defining type: DefId(0/1:20 ~ propagate_approximated_fail_no_postdom[317d]::supply[0]::{{closure}}[0]) with closure substs [
                i16,
-               for<'r, 's> extern "rust-call" fn((std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&'_#2r &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) &'_#3r u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>))
+               for<'r, 's> extern "rust-call" fn((std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&'_#2r &ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 's)) &'_#3r u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 's)) u32>))
            ]
 
 note: No external requirements

src/test/ui/nll/closure-requirements/propagate-approximated-ref.stderr

@@ -18,7 +18,7 @@ LL | |     });
    |
    = note: defining type: DefId(0/1:18 ~ propagate_approximated_ref[317d]::supply[0]::{{closure}}[0]) with closure substs [
                i16,
-               for<'r, 's, 't0, 't1, 't2, 't3> extern "rust-call" fn((&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>, &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 't0)) std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 't1)) &'_#2r u32>, &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 't2)) std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>, &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 't3)) std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 't1)) u32>))
+               for<'r, 's, 't0, 't1, 't2, 't3> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 'r)) std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 's)) u32>, &ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 't0)) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 't1)) &'_#2r u32>, &ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 't2)) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 's)) u32>, &ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 't3)) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 't1)) u32>))
            ]
    = note: number of external vids: 3
    = note: where '_#1r: '_#2r

src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-comparing-against-free.stderr

@@ -23,7 +23,7 @@ LL | |     })
    |
    = note: defining type: DefId(0/1:12 ~ propagate_approximated_shorter_to_static_comparing_against_free[317d]::case1[0]::{{closure}}[0]) with closure substs [
                i32,
-               for<'r> extern "rust-call" fn((std::cell::Cell<&'_#1r u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>))
+               for<'r> extern "rust-call" fn((std::cell::Cell<&'_#1r u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 'r)) u32>))
            ]
 
 note: No external requirements
@@ -51,7 +51,7 @@ LL | |     })
    |
    = note: defining type: DefId(0/1:13 ~ propagate_approximated_shorter_to_static_comparing_against_free[317d]::case2[0]::{{closure}}[0]) with closure substs [
                i32,
-               for<'r> extern "rust-call" fn((std::cell::Cell<&'_#1r u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>))
+               for<'r> extern "rust-call" fn((std::cell::Cell<&'_#1r u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BrNamed(crate0:DefIndex(0:0), 'r)) u32>))
            ]
    = note: number of external vids: 2
    = note: where '_#1r: '_#0r