diff --git a/src/librustc/ty/sty.rs b/src/librustc/ty/sty.rs
index 10cf9a4d692d..f484fda2ae15 100644
--- a/src/librustc/ty/sty.rs
+++ b/src/librustc/ty/sty.rs
@@ -989,11 +989,11 @@ impl<'a, 'gcx, 'tcx> ParamTy {
 ///     for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
 ///     ^          ^            |        |         |
 ///     |          |            |        |         |
-///     |          +------------+ 1      |         |
+///     |          +------------+ 0      |         |
 ///     |                                |         |
-///     +--------------------------------+ 2       |
+///     +--------------------------------+ 1       |
 ///     |                                          |
-///     +------------------------------------------+ 1
+///     +------------------------------------------+ 0
 ///
 /// In this type, there are two binders (the outer fn and the inner
 /// fn). We need to be able to determine, for any given region, which
@@ -1005,9 +1005,9 @@ impl<'a, 'gcx, 'tcx> ParamTy {
 ///
 /// Let's start with the reference type `&'b isize` that is the first
 /// argument to the inner function. This region `'b` is assigned a De
-/// Bruijn index of 1, meaning "the innermost binder" (in this case, a
+/// Bruijn index of 0, meaning "the innermost binder" (in this case, a
 /// fn). The region `'a` that appears in the second argument type (`&'a
-/// isize`) would then be assigned a De Bruijn index of 2, meaning "the
+/// isize`) would then be assigned a De Bruijn index of 1, meaning "the
 /// second-innermost binder". (These indices are written on the arrays
 /// in the diagram).
 ///
@@ -1017,7 +1017,7 @@ impl<'a, 'gcx, 'tcx> ParamTy {
 /// the outermost fn. But this time, this reference is not nested within
 /// any other binders (i.e., it is not an argument to the inner fn, but
 /// rather the outer one). Therefore, in this case, it is assigned a
-/// De Bruijn index of 1, because the innermost binder in that location
+/// De Bruijn index of 0, because the innermost binder in that location
 /// is the outer fn.
 ///
 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
@@ -1025,7 +1025,7 @@ impl<'a, 'gcx, 'tcx> ParamTy {
 pub struct DebruijnIndex {
     /// We maintain the invariant that this is never 0. So 1 indicates
     /// the innermost binder.
-    depth: u32,
+    index: u32,
 }
 
 pub type Region<'tcx> = &'tcx RegionKind;
@@ -1259,7 +1259,7 @@ impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
 }
 
 impl DebruijnIndex {
-    pub const INNERMOST: DebruijnIndex = DebruijnIndex { depth: 1 };
+    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
@@ -1273,7 +1273,7 @@ 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 { depth: self.depth + amount }
+        DebruijnIndex { index: self.index + amount }
     }
 
     /// Update this index in place by shifting it "in" through
@@ -1286,7 +1286,7 @@ impl DebruijnIndex {
     /// `amount` number of new binders.
     #[must_use]
     pub const fn shifted_out(self, amount: u32) -> DebruijnIndex {
-        DebruijnIndex { depth: self.depth - amount }
+        DebruijnIndex { index: self.index - amount }
     }
 
     /// Update in place by shifting out from `amount` binders.
@@ -1315,12 +1315,12 @@ 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.depth - Self::INNERMOST.depth)
+        self.shifted_out(to_binder.index - Self::INNERMOST.index)
     }
 }
 
 impl_stable_hash_for!(struct DebruijnIndex {
-    depth
+    index
 });
 
 /// Region utilities
diff --git a/src/test/ui/nll/closure-requirements/escape-argument-callee.stderr b/src/test/ui/nll/closure-requirements/escape-argument-callee.stderr
index d876c751a41d..a0ad8ee43809 100644
--- a/src/test/ui/nll/closure-requirements/escape-argument-callee.stderr
+++ b/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 { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) mut &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) i32, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't0)) i32))
+               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))
            ]
 
 note: No external requirements
diff --git a/src/test/ui/nll/closure-requirements/escape-argument.stderr b/src/test/ui/nll/closure-requirements/escape-argument.stderr
index a9a52aba8421..6aeb8d4fcd5c 100644
--- a/src/test/ui/nll/closure-requirements/escape-argument.stderr
+++ b/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 { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) mut &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) i32, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) i32))
+               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))
            ]
 
 note: No external requirements
diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-fail-no-postdom.stderr b/src/test/ui/nll/closure-requirements/propagate-approximated-fail-no-postdom.stderr
index ef5a31e40d44..26ad522f6f4d 100644
--- a/src/test/ui/nll/closure-requirements/propagate-approximated-fail-no-postdom.stderr
+++ b/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 { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&'_#2r &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) &'_#3r u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>))
+               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>))
            ]
 
 note: No external requirements
diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-ref.stderr b/src/test/ui/nll/closure-requirements/propagate-approximated-ref.stderr
index 3a3236fd16c4..537e951ddf1c 100644
--- a/src/test/ui/nll/closure-requirements/propagate-approximated-ref.stderr
+++ b/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 { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't0)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't1)) &'_#2r u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't2)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't3)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't1)) u32>))
+               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>))
            ]
    = note: number of external vids: 3
    = note: where '_#1r: '_#2r
diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-comparing-against-free.stderr b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-comparing-against-free.stderr
index 6480cbe44312..93ae534b25c9 100644
--- a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-comparing-against-free.stderr
+++ b/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 { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>))
+               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>))
            ]
 
 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 { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>))
+               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>))
            ]
    = note: number of external vids: 2
    = note: where '_#1r: '_#0r
diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr
index 6dcc8421177d..4081ec65f803 100644
--- a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr
+++ b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr
@@ -18,7 +18,7 @@ LL | |     });
    |
    = note: defining type: DefId(0/1:18 ~ propagate_approximated_shorter_to_static_no_bound[317d]::supply[0]::{{closure}}[0]) with closure substs [
                i16,
-               for<'r, 's, 't0, 't1, 't2> extern "rust-call" fn((&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't0)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't1)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't2)) u32>))
+               for<'r, 's, 't0, 't1, 't2> 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), 's)) u32>, &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 't1)) std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 't2)) u32>))
            ]
    = note: number of external vids: 2
    = note: where '_#1r: '_#0r
diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr
index 1291f2e9901b..7a745bb09642 100644
--- a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr
+++ b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr
@@ -18,7 +18,7 @@ LL | |     });
    |
    = note: defining type: DefId(0/1:18 ~ propagate_approximated_shorter_to_static_wrong_bound[317d]::supply[0]::{{closure}}[0]) with closure substs [
                i16,
-               for<'r, 's, 't0, 't1, 't2, 't3> extern "rust-call" fn((&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't0)) std::cell::Cell<&'_#2r &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't1)) u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't2)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't3)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't1)) u32>))
+               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<&'_#2r &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 't1)) 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>))
            ]
    = note: number of external vids: 3
    = note: where '_#1r: '_#0r
diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-val.stderr b/src/test/ui/nll/closure-requirements/propagate-approximated-val.stderr
index d1824a941510..4e2680585e9d 100644
--- a/src/test/ui/nll/closure-requirements/propagate-approximated-val.stderr
+++ b/src/test/ui/nll/closure-requirements/propagate-approximated-val.stderr
@@ -18,7 +18,7 @@ LL | |     });
    |
    = note: defining type: DefId(0/1:18 ~ propagate_approximated_val[317d]::test[0]::{{closure}}[0]) with closure substs [
                i16,
-               for<'r, 's> extern "rust-call" fn((std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) &'_#2r u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>))
+               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<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) &'_#2r 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>))
            ]
    = note: number of external vids: 3
    = note: where '_#1r: '_#2r
diff --git a/src/test/ui/nll/closure-requirements/propagate-despite-same-free-region.stderr b/src/test/ui/nll/closure-requirements/propagate-despite-same-free-region.stderr
index d6eeda881daf..2cc9a11dbc3c 100644
--- a/src/test/ui/nll/closure-requirements/propagate-despite-same-free-region.stderr
+++ b/src/test/ui/nll/closure-requirements/propagate-despite-same-free-region.stderr
@@ -16,7 +16,7 @@ LL | |         },
    |
    = note: defining type: DefId(0/1:16 ~ propagate_despite_same_free_region[317d]::supply[0]::{{closure}}[0]) with closure substs [
                i16,
-               for<'r, 's> extern "rust-call" fn((std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) &'_#2r u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>))
+               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<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) &'_#2r 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>))
            ]
    = note: number of external vids: 3
    = note: where '_#1r: '_#2r
diff --git a/src/test/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-no-bounds.stderr b/src/test/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-no-bounds.stderr
index ffae47bd081c..e53ece696c9f 100644
--- a/src/test/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-no-bounds.stderr
+++ b/src/test/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-no-bounds.stderr
@@ -24,7 +24,7 @@ LL | |     });
    |
    = note: defining type: DefId(0/1:18 ~ propagate_fail_to_approximate_longer_no_bounds[317d]::supply[0]::{{closure}}[0]) with closure substs [
                i16,
-               for<'r, 's, 't0, 't1, 't2> extern "rust-call" fn((&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) &'_#1r u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't0)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't1)) u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't2)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>))
+               for<'r, 's, 't0, 't1, 't2> extern "rust-call" fn((&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) &'_#1r u32>, &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 't0)) std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 't1)) 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>))
            ]
 
 note: No external requirements
diff --git a/src/test/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-wrong-bounds.stderr b/src/test/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-wrong-bounds.stderr
index 01af756b8332..45f308b2323c 100644
--- a/src/test/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-wrong-bounds.stderr
+++ b/src/test/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-wrong-bounds.stderr
@@ -24,7 +24,7 @@ LL | |     });
    |
    = note: defining type: DefId(0/1:18 ~ propagate_fail_to_approximate_longer_wrong_bounds[317d]::supply[0]::{{closure}}[0]) with closure substs [
                i16,
-               for<'r, 's, 't0, 't1, 't2, 't3> extern "rust-call" fn((&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) &'_#1r u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't0)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't1)) &'_#2r u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't2)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) u32>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't3)) std::cell::Cell<&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 't1)) u32>))
+               for<'r, 's, 't0, 't1, 't2, 't3> extern "rust-call" fn((&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) std::cell::Cell<&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) &'_#1r 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>))
            ]
 
 note: No external requirements
diff --git a/src/test/ui/nll/closure-requirements/return-wrong-bound-region.stderr b/src/test/ui/nll/closure-requirements/return-wrong-bound-region.stderr
index 4d021fb54549..9e6fd28565e6 100644
--- a/src/test/ui/nll/closure-requirements/return-wrong-bound-region.stderr
+++ b/src/test/ui/nll/closure-requirements/return-wrong-bound-region.stderr
@@ -18,7 +18,7 @@ LL |     expect_sig(|a, b| b); // ought to return `a`
    |
    = note: defining type: DefId(0/1:9 ~ return_wrong_bound_region[317d]::test[0]::{{closure}}[0]) with closure substs [
                i16,
-               for<'r, 's> extern "rust-call" fn((&ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) i32, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) i32)) -> &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) i32
+               for<'r, 's> extern "rust-call" fn((&ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) i32, &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) i32)) -> &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) i32
            ]
 
 note: No external requirements
diff --git a/src/test/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.stderr b/src/test/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.stderr
index b4f51401a90f..70bda0d7a186 100644
--- a/src/test/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.stderr
+++ b/src/test/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.stderr
@@ -25,7 +25,7 @@ LL |     twice(cell, value, |a, b| invoke(a, b));
    = note: defining type: DefId(0/1:14 ~ ty_param_closure_approximate_lower_bound[317d]::generic[0]::{{closure}}[0]) with closure substs [
                T,
                i16,
-               for<'r, 's> extern "rust-call" fn((std::option::Option<std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) ()>>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) T))
+               for<'r, 's> extern "rust-call" fn((std::option::Option<std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) ()>>, &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) T))
            ]
    = note: number of external vids: 2
    = note: where T: '_#1r
@@ -55,7 +55,7 @@ LL |     twice(cell, value, |a, b| invoke(a, b));
    = note: defining type: DefId(0/1:17 ~ ty_param_closure_approximate_lower_bound[317d]::generic_fail[0]::{{closure}}[0]) with closure substs [
                T,
                i16,
-               for<'r, 's> extern "rust-call" fn((std::option::Option<std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 'r)) ()>>, &ReLateBound(DebruijnIndex { depth: 1 }, BrNamed(crate0:DefIndex(0:0), 's)) T))
+               for<'r, 's> extern "rust-call" fn((std::option::Option<std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 'r)) ()>>, &ReLateBound(DebruijnIndex { index: 0 }, BrNamed(crate0:DefIndex(0:0), 's)) T))
            ]
    = note: number of external vids: 2
    = note: where T: '_#1r