Rollup merge of rust-lang#61150 - Centril:rollup-wmm7qga, r=Centril

Rollup of 13 pull requests

Successful merges:

 - rust-lang#61026 (Tweak macro parse errors when reaching EOF during macro call parse)
 - rust-lang#61095 (Update cargo)
 - rust-lang#61096 (tidy: don't short-circuit on license error)
 - rust-lang#61107 (Fix a couple docs typos)
 - rust-lang#61110 (Revert edition-guide toolstate override)
 - rust-lang#61111 (Fixed type-alias-bounds lint doc)
 - rust-lang#61113 (Deprecate `FnBox`. `Box<dyn FnOnce()>` can be called directly, since 1.35)
 - rust-lang#61116 (Remove the incorrect warning from README.md)
 - rust-lang#61118 (Dont ICE on an attempt to use GAT without feature gate)
 - rust-lang#61121 (improve debug-printing of scalars)
 - rust-lang#61125 (Updated my mailmap entry)
 - rust-lang#61134 (Annotate each `reverse_bits` with `#[must_use]`)
 - rust-lang#61138 (Move async/await tests to their own folder)

Failed merges:

r? @ghost

.mailmap

@@ -6,7 +6,7 @@
 #
 
 Aaron Todd <github@opprobrio.us>
-Aaron Power <theaaronepower@gmail.com>
+Aaron Power <theaaronepower@gmail.com> Erin Power <xampprocky@gmail.com>
 Abhishek Chanda <abhishek.becs@gmail.com> Abhishek Chanda <abhishek@cloudscaling.com>
 Adolfo Ochagavía <aochagavia92@gmail.com>
 Adrien Tétar <adri-from-59@hotmail.fr>

Cargo.lock

@@ -253,15 +253,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "cargo"
-version = "0.37.0"
+version = "0.38.0"
 dependencies = [
  "atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "bufstream 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 1.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "bytesize 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "core-foundation 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "crates-io 0.25.0",
+ "crates-io 0.26.0",
  "crossbeam-utils 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "crypto-hash 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "curl 0.4.21 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -278,7 +278,7 @@ dependencies = [
  "hex 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "home 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "ignore 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "im-rc 12.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "im-rc 13.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "jobserver 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazycell 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -300,6 +300,7 @@ dependencies = [
  "serde_ignored 0.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.33 (registry+https://github.com/rust-lang/crates.io-index)",
  "shell-escape 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "strip-ansi-escapes 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "tar 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
  "tempfile 3.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "termcolor 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -537,7 +538,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "crates-io"
-version = "0.25.0"
+version = "0.26.0"
 dependencies = [
  "curl 0.4.21 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1163,10 +1164,11 @@ dependencies = [
 
 [[package]]
 name = "im-rc"
-version = "12.3.0"
+version = "13.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "sized-chunks 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "typenum 1.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -2239,7 +2241,7 @@ dependencies = [
 name = "rls"
 version = "1.36.0"
 dependencies = [
- "cargo 0.37.0",
+ "cargo 0.38.0",
  "cargo_metadata 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "clippy_lints 0.0.212",
  "crossbeam-channel 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3263,6 +3265,14 @@ name = "siphasher"
 version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "sized-chunks"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "typenum 1.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "slab"
 version = "0.4.2"
@@ -3348,6 +3358,14 @@ name = "string_cache_shared"
 version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "strip-ansi-escapes"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "vte 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "strsim"
 version = "0.7.0"
@@ -3924,6 +3942,11 @@ name = "utf8-ranges"
 version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "utf8parse"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "vcpkg"
 version = "0.2.6"
@@ -3954,6 +3977,14 @@ name = "void"
 version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "vte"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "utf8parse 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "wait-timeout"
 version = "0.1.5"
@@ -4158,7 +4189,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum idna 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "38f09e0f0b1fb55fdee1f17470ad800da77af5186a1a76c026b679358b7e844e"
 "checksum if_chain 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4bac95d9aa0624e7b78187d6fb8ab012b41d9f6f54b1bcb61e61c4845f8357ec"
 "checksum ignore 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)" = "8dc57fa12805f367736a38541ac1a9fc6a52812a0ca959b1d4d4b640a89eb002"
-"checksum im-rc 12.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9460397452f537fd51808056ff209f4c4c4c9d20d42ae952f517708726284972"
+"checksum im-rc 13.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0a0197597d095c0d11107975d3175173f810ee572c2501ff4de64f4f3f119806"
 "checksum iovec 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "dbe6e417e7d0975db6512b90796e8ce223145ac4e33c377e4a42882a0e88bb08"
 "checksum is-match 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7e5b386aef33a1c677be65237cb9d32c3f3ef56bd035949710c4bb13083eb053"
 "checksum itertools 0.7.8 (registry+https://github.com/rust-lang/crates.io-index)" = "f58856976b776fedd95533137617a02fb25719f40e7d9b01c7043cd65474f450"
@@ -4309,13 +4340,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum shlex 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7fdf1b9db47230893d76faad238fd6097fd6d6a9245cd7a4d90dbd639536bbd2"
 "checksum signal-hook 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "1f272d1b7586bec132ed427f532dd418d8beca1ca7f2caf7df35569b1415a4b4"
 "checksum siphasher 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "0df90a788073e8d0235a67e50441d47db7c8ad9debd91cbf43736a2a92d36537"
+"checksum sized-chunks 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "a2a2eb3fe454976eefb479f78f9b394d34d661b647c6326a3a6e66f68bb12c26"
 "checksum slab 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)" = "c111b5bd5695e56cffe5129854aa230b39c93a305372fdbb2668ca2394eea9f8"
 "checksum smallvec 0.6.7 (registry+https://github.com/rust-lang/crates.io-index)" = "b73ea3738b47563803ef814925e69be00799a8c07420be8b996f8e98fb2336db"
 "checksum socket2 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)" = "c4d11a52082057d87cb5caa31ad812f4504b97ab44732cd8359df2e9ff9f48e7"
 "checksum stable_deref_trait 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ffbc596e092fe5f598b12ef46cc03754085ac2f4d8c739ad61c4ae266cc3b3fa"
 "checksum string_cache 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)" = "25d70109977172b127fe834e5449e5ab1740b9ba49fa18a2020f509174f25423"
 "checksum string_cache_codegen 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)" = "1eea1eee654ef80933142157fdad9dd8bc43cf7c74e999e369263496f04ff4da"
 "checksum string_cache_shared 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b1884d1bc09741d466d9b14e6d37ac89d6909cbcac41dd9ae982d4d063bbedfc"
+"checksum strip-ansi-escapes 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9d63676e2abafa709460982ddc02a3bb586b6d15a49b75c212e06edd3933acee"
 "checksum strsim 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "bb4f380125926a99e52bc279241539c018323fab05ad6368b56f93d9369ff550"
 "checksum strum 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f6c3a2071519ab6a48f465808c4c1ffdd00dfc8e93111d02b4fc5abab177676e"
 "checksum strum_macros 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8baacebd7b7c9b864d83a6ba7a246232983e277b86fa5cdec77f565715a4b136"
@@ -4368,11 +4401,13 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum url_serde 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "74e7d099f1ee52f823d4bdd60c93c3602043c728f5db3b97bdb548467f7bddea"
 "checksum utf-8 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f1262dfab4c30d5cb7c07026be00ee343a6cf5027fdc0104a9160f354e5db75c"
 "checksum utf8-ranges 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "796f7e48bef87609f7ade7e06495a87d5cd06c7866e6a5cbfceffc558a243737"
+"checksum utf8parse 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "8772a4ccbb4e89959023bc5b7cb8623a795caa7092d99f3aa9501b9484d4557d"
 "checksum vcpkg 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "def296d3eb3b12371b2c7d0e83bfe1403e4db2d7a0bba324a12b21c4ee13143d"
 "checksum vec_map 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)" = "05c78687fb1a80548ae3250346c3db86a80a7cdd77bda190189f2d0a0987c81a"
 "checksum vergen 3.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "6aba5e34f93dc7051dfad05b98a18e9156f27e7b431fe1d2398cb6061c0a1dba"
 "checksum version_check 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "914b1a6776c4c929a602fafd8bc742e06365d4bcbe48c30f9cca5824f70dc9dd"
 "checksum void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6a02e4885ed3bc0f2de90ea6dd45ebcbb66dacffe03547fadbb0eeae2770887d"
+"checksum vte 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4f42f536e22f7fcbb407639765c8fd78707a33109301f834a594758bedd6e8cf"
 "checksum wait-timeout 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "b9f3bf741a801531993db6478b95682117471f76916f5e690dd8d45395b09349"
 "checksum walkdir 2.2.7 (registry+https://github.com/rust-lang/crates.io-index)" = "9d9d7ed3431229a144296213105a390676cc49c9b6a72bd19f3176c98e129fa1"
 "checksum winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)" = "167dc9d6949a9b857f3451275e911c3f44255842c1f7a76f33c55103a909087a"

README.md

@@ -134,9 +134,8 @@ MSVC builds of Rust additionally require an installation of Visual Studio 2017
 
 [Visual Studio Build Tools]: https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2019
 
-At last check (cmake 3.14.3 and msvc 16.0.3) using the 2019 tools fails to
-build the in-tree LLVM build with a CMake error, so use 2017 instead by
-including the “MSVC v141 – VS 2017 C++ x64/x86 build tools (v14.16)” component.
+(If you're installing cmake yourself, be careful that “C++ CMake tools for
+Windows” doesn't get included under “Individual components”.)
 
 With these dependencies installed, you can build the compiler in a `cmd.exe`
 shell with:
@@ -151,7 +150,7 @@ then you may need to force rustbuild to use an older version. This can be done
 by manually calling the appropriate vcvars file before running the bootstrap.
 
 ```batch
-> CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\vcvars64.bat"
+> CALL "C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Auxiliary\Build\vcvars64.bat"
 > python x.py build
 ```
 

src/ci/docker/x86_64-gnu-tools/checktools.sh

@@ -74,9 +74,7 @@ status_check() {
     check_dispatch $1 beta nomicon src/doc/nomicon
     check_dispatch $1 beta reference src/doc/reference
     check_dispatch $1 beta rust-by-example src/doc/rust-by-example
-    # Temporarily disabled until
-    # https://github.com/rust-lang/rust/issues/60459 is fixed.
-    # check_dispatch $1 beta edition-guide src/doc/edition-guide
+    check_dispatch $1 beta edition-guide src/doc/edition-guide
     check_dispatch $1 beta rls src/tools/rls
     check_dispatch $1 beta rustfmt src/tools/rustfmt
     check_dispatch $1 beta clippy-driver src/tools/clippy

src/doc/rustc/src/lints/listing/warn-by-default.md

@@ -529,18 +529,21 @@ This lint detects bounds in type aliases. These are not currently enforced.
 Some example code that triggers this lint:
 
 ```rust
+#[allow(dead_code)]
 type SendVec<T: Send> = Vec<T>;
 ```
 
 This will produce:
 
 ```text
-warning: type alias is never used: `SendVec`
- --> src/main.rs:1:1
+warning: bounds on generic parameters are not enforced in type aliases
+ --> src/lib.rs:2:17
   |
-1 | type SendVec<T: Send> = Vec<T>;
-  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+2 | type SendVec<T: Send> = Vec<T>;
+  |                 ^^^^
   |
+  = note: #[warn(type_alias_bounds)] on by default
+  = help: the bound will not be checked when the type alias is used, and should be removed
 ```
 
 ## tyvar-behind-raw-pointer

src/liballoc/boxed.rs

@@ -759,13 +759,14 @@ impl<A, F: Fn<A> + ?Sized> Fn<A> for Box<F> {
     }
 }
 
+/// `FnBox` is deprecated and will be removed.
+/// `Box<dyn FnOnce()>` can be called directly, since Rust 1.35.0.
+///
 /// `FnBox` is a version of the `FnOnce` intended for use with boxed
-/// closure objects. The idea is that where one would normally store a
-/// `Box<dyn FnOnce()>` in a data structure, you should use
+/// closure objects. The idea was that where one would normally store a
+/// `Box<dyn FnOnce()>` in a data structure, you whould use
 /// `Box<dyn FnBox()>`. The two traits behave essentially the same, except
-/// that a `FnBox` closure can only be called if it is boxed. (Note
-/// that `FnBox` may be deprecated in the future if `Box<dyn FnOnce()>`
-/// closures become directly usable.)
+/// that a `FnBox` closure can only be called if it is boxed.
 ///
 /// # Examples
 ///
@@ -777,6 +778,7 @@ impl<A, F: Fn<A> + ?Sized> Fn<A> for Box<F> {
 ///
 /// ```
 /// #![feature(fnbox)]
+/// #![allow(deprecated)]
 ///
 /// use std::boxed::FnBox;
 /// use std::collections::HashMap;
@@ -796,16 +798,38 @@ impl<A, F: Fn<A> + ?Sized> Fn<A> for Box<F> {
 ///     }
 /// }
 /// ```
+///
+/// In Rust 1.35.0 or later, use `FnOnce`, `FnMut`, or `Fn` instead:
+///
+/// ```
+/// use std::collections::HashMap;
+///
+/// fn make_map() -> HashMap<i32, Box<dyn FnOnce() -> i32>> {
+///     let mut map: HashMap<i32, Box<dyn FnOnce() -> i32>> = HashMap::new();
+///     map.insert(1, Box::new(|| 22));
+///     map.insert(2, Box::new(|| 44));
+///     map
+/// }
+///
+/// fn main() {
+///     let mut map = make_map();
+///     for i in &[1, 2] {
+///         let f = map.remove(&i).unwrap();
+///         assert_eq!(f(), i * 22);
+///     }
+/// }
+/// ```
 #[rustc_paren_sugar]
-#[unstable(feature = "fnbox",
-           reason = "will be deprecated if and when `Box<FnOnce>` becomes usable", issue = "28796")]
+#[unstable(feature = "fnbox", issue = "28796")]
+#[rustc_deprecated(reason = "use `FnOnce`, `FnMut`, or `Fn` instead", since = "1.37.0")]
 pub trait FnBox<A>: FnOnce<A> {
     /// Performs the call operation.
     fn call_box(self: Box<Self>, args: A) -> Self::Output;
 }
 
-#[unstable(feature = "fnbox",
-           reason = "will be deprecated if and when `Box<FnOnce>` becomes usable", issue = "28796")]
+#[unstable(feature = "fnbox", issue = "28796")]
+#[rustc_deprecated(reason = "use `FnOnce`, `FnMut`, or `Fn` instead", since = "1.37.0")]
+#[allow(deprecated, deprecated_in_future)]
 impl<A, F> FnBox<A> for F
     where F: FnOnce<A>
 {

src/libcore/cell.rs

@@ -11,7 +11,7 @@
 //! mutate it.
 //!
 //! Shareable mutable containers exist to permit mutability in a controlled manner, even in the
-//! presence of aliasing. Both `Cell<T>` and `RefCell<T>` allows to do this in a single threaded
+//! presence of aliasing. Both `Cell<T>` and `RefCell<T>` allow doing this in a single-threaded
 //! way. However, neither `Cell<T>` nor `RefCell<T>` are thread safe (they do not implement
 //! `Sync`). If you need to do aliasing and mutation between multiple threads it is possible to
 //! use [`Mutex`](../../std/sync/struct.Mutex.html),

src/libcore/num/mod.rs

@@ -473,6 +473,7 @@ assert_eq!(m, ", $reversed, ");
             #[unstable(feature = "reverse_bits", issue = "48763")]
             #[rustc_const_unstable(feature = "const_int_conversion")]
             #[inline]
+            #[must_use]
             pub const fn reverse_bits(self) -> Self {
                 (self as $UnsignedT).reverse_bits() as Self
             }
@@ -2522,6 +2523,7 @@ assert_eq!(m, ", $reversed, ");
 ```"),
             #[unstable(feature = "reverse_bits", issue = "48763")]
             #[inline]
+            #[must_use]
             pub const fn reverse_bits(self) -> Self {
                 intrinsics::bitreverse(self as $ActualT) as Self
             }

src/libcore/num/wrapping.rs

@@ -524,6 +524,7 @@ assert_eq!(n.trailing_zeros(), 3);
             /// ```
             #[unstable(feature = "reverse_bits", issue = "48763")]
             #[inline]
+            #[must_use]
             pub const fn reverse_bits(self) -> Self {
                 Wrapping(self.0.reverse_bits())
             }

src/librustc/middle/region.rs

@@ -658,12 +658,15 @@ impl<'tcx> ScopeTree {
             // The lifetime was defined on node that doesn't own a body,
             // which in practice can only mean a trait or an impl, that
             // is the parent of a method, and that is enforced below.
-            assert_eq!(Some(param_owner_id), self.root_parent,
-                       "free_scope: {:?} not recognized by the \
-                        region scope tree for {:?} / {:?}",
-                       param_owner,
-                       self.root_parent.map(|id| tcx.hir().local_def_id_from_hir_id(id)),
-                       self.root_body.map(|hir_id| DefId::local(hir_id.owner)));
+            if Some(param_owner_id) != self.root_parent {
+                tcx.sess.delay_span_bug(
+                    DUMMY_SP,
+                    &format!("free_scope: {:?} not recognized by the \
+                              region scope tree for {:?} / {:?}",
+                             param_owner,
+                             self.root_parent.map(|id| tcx.hir().local_def_id_from_hir_id(id)),
+                             self.root_body.map(|hir_id| DefId::local(hir_id.owner))));
+            }
 
             // The trait/impl lifetime is in scope for the method's body.
             self.root_body.unwrap().local_id

src/librustc/mir/interpret/pointer.rs

@@ -1,3 +1,5 @@
+use std::fmt;
+
 use crate::mir;
 use crate::ty::layout::{self, HasDataLayout, Size};
 use rustc_macros::HashStable;
@@ -70,7 +72,7 @@ impl<T: layout::HasDataLayout> PointerArithmetic for T {}
 ///
 /// Pointer is also generic over the `Tag` associated with each pointer,
 /// which is used to do provenance tracking during execution.
-#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd,
+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd,
          RustcEncodable, RustcDecodable, Hash, HashStable)]
 pub struct Pointer<Tag=(),Id=AllocId> {
     pub alloc_id: Id,
@@ -80,6 +82,18 @@ pub struct Pointer<Tag=(),Id=AllocId> {
 
 static_assert_size!(Pointer, 16);
 
+impl<Tag: fmt::Debug, Id: fmt::Debug> fmt::Debug for Pointer<Tag, Id> {
+    default fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}.{:#x}[{:?}]", self.alloc_id, self.offset.bytes(), self.tag)
+    }
+}
+// Specialization for no tag
+impl<Id: fmt::Debug> fmt::Debug for Pointer<(), Id> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}.{:#x}", self.alloc_id, self.offset.bytes())
+    }
+}
+
 /// Produces a `Pointer` which points to the beginning of the Allocation
 impl From<AllocId> for Pointer {
     #[inline(always)]