From a043acd0b2cb9cb510cdeb040c0ce881af376142 Mon Sep 17 00:00:00 2001
From: Frank Steffahn <frank.steffahn@stu.uni-kiel.de>
Date: Fri, 7 Jan 2022 00:39:48 +0100
Subject: [PATCH 01/26] change PhantomData type for BuildHasherDefault

---
 library/core/src/hash/mod.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/core/src/hash/mod.rs b/library/core/src/hash/mod.rs
index 3ff84cc9672eb..53de8b42c059f 100644
--- a/library/core/src/hash/mod.rs
+++ b/library/core/src/hash/mod.rs
@@ -602,7 +602,7 @@ pub trait BuildHasher {
 /// [`HashSet`]: ../../std/collections/struct.HashSet.html
 /// [zero-sized]: https://doc.rust-lang.org/nomicon/exotic-sizes.html#zero-sized-types-zsts
 #[stable(since = "1.7.0", feature = "build_hasher")]
-pub struct BuildHasherDefault<H>(marker::PhantomData<H>);
+pub struct BuildHasherDefault<H>(marker::PhantomData<fn() -> H>);
 
 #[stable(since = "1.9.0", feature = "core_impl_debug")]
 impl<H> fmt::Debug for BuildHasherDefault<H> {

From 731bbae816e49cb404f402e8a5d392059e417ee5 Mon Sep 17 00:00:00 2001
From: Frank Steffahn <frank.steffahn@stu.uni-kiel.de>
Date: Fri, 7 Jan 2022 01:52:42 +0100
Subject: [PATCH 02/26] Also change PhantomData parameter of iter::Empty, and
 future::Pending

---
 library/core/src/future/pending.rs     |  5 +----
 library/core/src/iter/sources/empty.rs | 12 ++++++------
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/library/core/src/future/pending.rs b/library/core/src/future/pending.rs
index 560dd25ecff42..2877e66eca885 100644
--- a/library/core/src/future/pending.rs
+++ b/library/core/src/future/pending.rs
@@ -12,7 +12,7 @@ use crate::task::{Context, Poll};
 #[stable(feature = "future_readiness_fns", since = "1.48.0")]
 #[must_use = "futures do nothing unless you `.await` or poll them"]
 pub struct Pending<T> {
-    _data: marker::PhantomData<T>,
+    _data: marker::PhantomData<fn() -> T>,
 }
 
 /// Creates a future which never resolves, representing a computation that never
@@ -43,9 +43,6 @@ impl<T> Future for Pending<T> {
     }
 }
 
-#[stable(feature = "future_readiness_fns", since = "1.48.0")]
-impl<T> Unpin for Pending<T> {}
-
 #[stable(feature = "future_readiness_fns", since = "1.48.0")]
 impl<T> Debug for Pending<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
diff --git a/library/core/src/iter/sources/empty.rs b/library/core/src/iter/sources/empty.rs
index 7abe01d17c90b..98734c527f2b9 100644
--- a/library/core/src/iter/sources/empty.rs
+++ b/library/core/src/iter/sources/empty.rs
@@ -22,17 +22,17 @@ pub const fn empty<T>() -> Empty<T> {
     Empty(marker::PhantomData)
 }
 
+// Newtype for use in `PhantomData` to avoid
+// > error: const-stable function cannot use `#[feature(const_fn_fn_ptr_basics)]`
+// in `const fn empty<T>()` above.
+struct FnReturning<T>(fn() -> T);
+
 /// An iterator that yields nothing.
 ///
 /// This `struct` is created by the [`empty()`] function. See its documentation for more.
 #[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "iter_empty", since = "1.2.0")]
-pub struct Empty<T>(marker::PhantomData<T>);
-
-#[stable(feature = "iter_empty_send_sync", since = "1.42.0")]
-unsafe impl<T> Send for Empty<T> {}
-#[stable(feature = "iter_empty_send_sync", since = "1.42.0")]
-unsafe impl<T> Sync for Empty<T> {}
+pub struct Empty<T>(marker::PhantomData<FnReturning<T>>);
 
 #[stable(feature = "core_impl_debug", since = "1.9.0")]
 impl<T> fmt::Debug for Empty<T> {

From 6a1f9e6fc7272599de76fec37e31db4978780649 Mon Sep 17 00:00:00 2001
From: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>
Date: Sun, 26 Dec 2021 22:12:41 +0800
Subject: [PATCH 03/26] mangling_v0: Update tests for the rust-demangler tool

---
 src/tools/rust-demangler/tests/lib.rs | 32 +++++++++++++--------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/src/tools/rust-demangler/tests/lib.rs b/src/tools/rust-demangler/tests/lib.rs
index 5a67b42322535..85019df7867dd 100644
--- a/src/tools/rust-demangler/tests/lib.rs
+++ b/src/tools/rust-demangler/tests/lib.rs
@@ -29,14 +29,14 @@ cc[4d6468d6c9fd4bb3]::spawn::{closure#0}::{closure#0}
 <core[846817f741e54dfd]::slice::Iter<u8> as core[846817f741e54dfd]::iter::iterator::Iterator>::rposition::<core[846817f741e54dfd]::slice::memchr::memrchr::{closure#1}>::{closure#0}
 alloc[f15a878b47eb696b]::alloc::box_free::<dyn alloc[f15a878b47eb696b]::boxed::FnBox<(), Output = ()>>
 INtC8arrayvec8ArrayVechKj7b_E
-<const_generic[317d481089b8c8fe]::Unsigned<11: u8>>
-<const_generic[317d481089b8c8fe]::Signed<152: i16>>
-<const_generic[317d481089b8c8fe]::Signed<-11: i8>>
-<const_generic[317d481089b8c8fe]::Bool<false: bool>>
-<const_generic[317d481089b8c8fe]::Bool<true: bool>>
-<const_generic[317d481089b8c8fe]::Char<'v': char>>
-<const_generic[317d481089b8c8fe]::Char<'\n': char>>
-<const_generic[317d481089b8c8fe]::Char<'∂': char>>
+<const_generic[317d481089b8c8fe]::Unsigned<11u8>>
+<const_generic[317d481089b8c8fe]::Signed<152i16>>
+<const_generic[317d481089b8c8fe]::Signed<-11i8>>
+<const_generic[317d481089b8c8fe]::Bool<false>>
+<const_generic[317d481089b8c8fe]::Bool<true>>
+<const_generic[317d481089b8c8fe]::Char<'v'>>
+<const_generic[317d481089b8c8fe]::Char<'\n'>>
+<const_generic[317d481089b8c8fe]::Char<'∂'>>
 <const_generic[317d481089b8c8fe]::Foo<_>>::foo::FOO
 foo[0]
 foo[0]
@@ -51,14 +51,14 @@ cc::spawn::{closure#0}::{closure#0}
 <core::slice::Iter<u8> as core::iter::iterator::Iterator>::rposition::<core::slice::memchr::memrchr::{closure#1}>::{closure#0}
 alloc::alloc::box_free::<dyn alloc::boxed::FnBox<(), Output = ()>>
 INtC8arrayvec8ArrayVechKj7b_E
-<const_generic::Unsigned<11: u8>>
-<const_generic::Signed<152: i16>>
-<const_generic::Signed<-11: i8>>
-<const_generic::Bool<false: bool>>
-<const_generic::Bool<true: bool>>
-<const_generic::Char<'v': char>>
-<const_generic::Char<'\n': char>>
-<const_generic::Char<'∂': char>>
+<const_generic::Unsigned<11u8>>
+<const_generic::Signed<152i16>>
+<const_generic::Signed<-11i8>>
+<const_generic::Bool<false>>
+<const_generic::Bool<true>>
+<const_generic::Char<'v'>>
+<const_generic::Char<'\n'>>
+<const_generic::Char<'∂'>>
 <const_generic::Foo<_>>::foo::FOO
 foo[0]
 foo[0]

From 1b8daf8c58267a5d9fae2021a311dfbbda11b02f Mon Sep 17 00:00:00 2001
From: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>
Date: Mon, 27 Dec 2021 20:05:22 +0800
Subject: [PATCH 04/26] mangling_v0: Add a test for mangling of foreign types

---
 src/test/ui/symbol-names/foreign-types.rs     | 19 ++++++++++++++++++
 src/test/ui/symbol-names/foreign-types.stderr | 20 +++++++++++++++++++
 2 files changed, 39 insertions(+)
 create mode 100644 src/test/ui/symbol-names/foreign-types.rs
 create mode 100644 src/test/ui/symbol-names/foreign-types.stderr

diff --git a/src/test/ui/symbol-names/foreign-types.rs b/src/test/ui/symbol-names/foreign-types.rs
new file mode 100644
index 0000000000000..33c5e6adfef29
--- /dev/null
+++ b/src/test/ui/symbol-names/foreign-types.rs
@@ -0,0 +1,19 @@
+// build-fail
+// compile-flags: -Z symbol-mangling-version=v0
+
+#![feature(extern_types)]
+#![feature(rustc_attrs)]
+
+extern "C" {
+    type ForeignType;
+}
+
+struct Check<T: ?Sized>(T);
+
+#[rustc_symbol_name]
+//~^ ERROR symbol-name(_RMCs
+//~| ERROR demangling(<foreign_types[
+//~| ERROR demangling-alt(<foreign_types::Check<foreign_types::ForeignType>>)
+impl Check<ForeignType> {}
+
+fn main() {}
diff --git a/src/test/ui/symbol-names/foreign-types.stderr b/src/test/ui/symbol-names/foreign-types.stderr
new file mode 100644
index 0000000000000..c6c59a6c82ea7
--- /dev/null
+++ b/src/test/ui/symbol-names/foreign-types.stderr
@@ -0,0 +1,20 @@
+error: symbol-name(_RMCsCRATE_HASH_13foreign_typesINtB<REF>_5CheckNvNtB<REF>_011ForeignTypeE)
+  --> $DIR/foreign-types.rs:13:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling(<foreign_types[HASH]::Check<foreign_types[HASH]::ForeignType>>)
+  --> $DIR/foreign-types.rs:13:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling-alt(<foreign_types::Check<foreign_types::ForeignType>>)
+  --> $DIR/foreign-types.rs:13:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+

From 333a5cc3691a96aab461ebcbc6064ee79356f1ae Mon Sep 17 00:00:00 2001
From: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>
Date: Mon, 27 Dec 2021 20:09:20 +0800
Subject: [PATCH 05/26] mangling_v0: Skip extern blocks during mangling

---
 compiler/rustc_symbol_mangling/src/v0.rs      | 6 +++---
 src/test/ui/symbol-names/foreign-types.rs     | 2 +-
 src/test/ui/symbol-names/foreign-types.stderr | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/compiler/rustc_symbol_mangling/src/v0.rs b/compiler/rustc_symbol_mangling/src/v0.rs
index c2519adcbe416..fbb9e28d182f8 100644
--- a/compiler/rustc_symbol_mangling/src/v0.rs
+++ b/compiler/rustc_symbol_mangling/src/v0.rs
@@ -771,9 +771,9 @@ impl<'tcx> Printer<'tcx> for &mut SymbolMangler<'tcx> {
         disambiguated_data: &DisambiguatedDefPathData,
     ) -> Result<Self::Path, Self::Error> {
         let ns = match disambiguated_data.data {
-            // FIXME: It shouldn't be necessary to add anything for extern block segments,
-            // but we add 't' for backward compatibility.
-            DefPathData::ForeignMod => 't',
+            // Extern block segments can be skipped, names from extern blocks
+            // are effectively living in their parent modules.
+            DefPathData::ForeignMod => return print_prefix(self),
 
             // Uppercase categories are more stable than lowercase ones.
             DefPathData::TypeNs(_) => 't',
diff --git a/src/test/ui/symbol-names/foreign-types.rs b/src/test/ui/symbol-names/foreign-types.rs
index 33c5e6adfef29..8f5b07769caff 100644
--- a/src/test/ui/symbol-names/foreign-types.rs
+++ b/src/test/ui/symbol-names/foreign-types.rs
@@ -1,5 +1,5 @@
 // build-fail
-// compile-flags: -Z symbol-mangling-version=v0
+// compile-flags: -C symbol-mangling-version=v0
 
 #![feature(extern_types)]
 #![feature(rustc_attrs)]
diff --git a/src/test/ui/symbol-names/foreign-types.stderr b/src/test/ui/symbol-names/foreign-types.stderr
index c6c59a6c82ea7..fcffdd2a8ec15 100644
--- a/src/test/ui/symbol-names/foreign-types.stderr
+++ b/src/test/ui/symbol-names/foreign-types.stderr
@@ -1,4 +1,4 @@
-error: symbol-name(_RMCsCRATE_HASH_13foreign_typesINtB<REF>_5CheckNvNtB<REF>_011ForeignTypeE)
+error: symbol-name(_RMCsCRATE_HASH_13foreign_typesINtB<REF>_5CheckNvB<REF>_11ForeignTypeE)
   --> $DIR/foreign-types.rs:13:1
    |
 LL | #[rustc_symbol_name]

From 3c0fb7f36d872184b67884838b967d0b57dbf3a2 Mon Sep 17 00:00:00 2001
From: Eric Huss <eric@huss.org>
Date: Tue, 11 Jan 2022 17:00:07 -0800
Subject: [PATCH 06/26] Add manifest docs fallback.

---
 src/tools/build-manifest/src/main.rs     | 95 +++++++++++++++---------
 src/tools/build-manifest/src/versions.rs |  8 +-
 2 files changed, 62 insertions(+), 41 deletions(-)

diff --git a/src/tools/build-manifest/src/main.rs b/src/tools/build-manifest/src/main.rs
index c1579ae9ac54a..d3bce6b3e8df5 100644
--- a/src/tools/build-manifest/src/main.rs
+++ b/src/tools/build-manifest/src/main.rs
@@ -155,17 +155,19 @@ static TARGETS: &[&str] = &[
     "x86_64-unknown-hermit",
 ];
 
-static DOCS_TARGETS: &[&str] = &[
-    "aarch64-unknown-linux-gnu",
-    "i686-apple-darwin",
-    "i686-pc-windows-gnu",
-    "i686-pc-windows-msvc",
-    "i686-unknown-linux-gnu",
-    "x86_64-apple-darwin",
-    "x86_64-pc-windows-gnu",
-    "x86_64-pc-windows-msvc",
-    "x86_64-unknown-linux-gnu",
-    "x86_64-unknown-linux-musl",
+/// This allows the manifest to contain rust-docs for hosts that don't build
+/// docs.
+///
+/// Tuples of `(host_partial, host_instead)`. If the host does not have the
+/// rust-docs component available, then if the host name contains
+/// `host_partial`, it will use the docs from `host_instead` instead.
+///
+/// The order here matters, more specific entries should be first.
+static DOCS_FALLBACK: &[(&str, &str)] = &[
+    ("-apple-", "x86_64-apple-darwin"),
+    ("aarch64", "aarch64-unknown-linux-gnu"),
+    ("arm-", "aarch64-unknown-linux-gnu"),
+    ("", "x86_64-unknown-linux-gnu"),
 ];
 
 static MSI_INSTALLERS: &[&str] = &[
@@ -301,23 +303,27 @@ impl Builder {
     }
 
     fn add_packages_to(&mut self, manifest: &mut Manifest) {
-        let mut package = |name, targets| self.package(name, &mut manifest.pkg, targets);
-        package("rustc", HOSTS);
-        package("rustc-dev", HOSTS);
-        package("reproducible-artifacts", HOSTS);
-        package("rustc-docs", HOSTS);
-        package("cargo", HOSTS);
-        package("rust-mingw", MINGW);
-        package("rust-std", TARGETS);
-        package("rust-docs", DOCS_TARGETS);
-        package("rust-src", &["*"]);
-        package("rls-preview", HOSTS);
-        package("rust-analyzer-preview", HOSTS);
-        package("clippy-preview", HOSTS);
-        package("miri-preview", HOSTS);
-        package("rustfmt-preview", HOSTS);
-        package("rust-analysis", TARGETS);
-        package("llvm-tools-preview", TARGETS);
+        macro_rules! package {
+            ($name:expr, $targets:expr) => {
+                self.package($name, &mut manifest.pkg, $targets, &[])
+            };
+        }
+        package!("rustc", HOSTS);
+        package!("rustc-dev", HOSTS);
+        package!("reproducible-artifacts", HOSTS);
+        package!("rustc-docs", HOSTS);
+        package!("cargo", HOSTS);
+        package!("rust-mingw", MINGW);
+        package!("rust-std", TARGETS);
+        self.package("rust-docs", &mut manifest.pkg, HOSTS, DOCS_FALLBACK);
+        package!("rust-src", &["*"]);
+        package!("rls-preview", HOSTS);
+        package!("rust-analyzer-preview", HOSTS);
+        package!("clippy-preview", HOSTS);
+        package!("miri-preview", HOSTS);
+        package!("rustfmt-preview", HOSTS);
+        package!("rust-analysis", TARGETS);
+        package!("llvm-tools-preview", TARGETS);
     }
 
     fn add_artifacts_to(&mut self, manifest: &mut Manifest) {
@@ -500,7 +506,13 @@ impl Builder {
             .extend(pkgs.iter().map(|s| (*s).to_owned()));
     }
 
-    fn package(&mut self, pkgname: &str, dst: &mut BTreeMap<String, Package>, targets: &[&str]) {
+    fn package(
+        &mut self,
+        pkgname: &str,
+        dst: &mut BTreeMap<String, Package>,
+        targets: &[&str],
+        fallback: &[(&str, &str)],
+    ) {
         let version_info = self
             .versions
             .version(&PkgType::from_component(pkgname))
@@ -512,16 +524,29 @@ impl Builder {
             is_present = false; // Pretend the component is entirely missing.
         }
 
+        macro_rules! tarball_name {
+            ($target_name:expr) => {
+                self.versions.tarball_name(&PkgType::from_component(pkgname), $target_name).unwrap()
+            };
+        }
+        let mut target_from_compressed_tar = |target_name| {
+            let target = Target::from_compressed_tar(self, &tarball_name!(target_name));
+            if target.available {
+                return target;
+            }
+            for (substr, fallback_target) in fallback {
+                if target_name.contains(substr) {
+                    return Target::from_compressed_tar(self, &tarball_name!(fallback_target));
+                }
+            }
+            Target::unavailable()
+        };
+
         let targets = targets
             .iter()
             .map(|name| {
                 let target = if is_present {
-                    let filename = self
-                        .versions
-                        .tarball_name(&PkgType::from_component(pkgname), name)
-                        .unwrap();
-
-                    Target::from_compressed_tar(self, &filename)
+                    target_from_compressed_tar(name)
                 } else {
                     // If the component is not present for this build add it anyway but mark it as
                     // unavailable -- this way rustup won't allow upgrades without --force
diff --git a/src/tools/build-manifest/src/versions.rs b/src/tools/build-manifest/src/versions.rs
index 11575139adcf6..95c2297de264b 100644
--- a/src/tools/build-manifest/src/versions.rs
+++ b/src/tools/build-manifest/src/versions.rs
@@ -169,7 +169,7 @@ impl Versions {
     }
 
     pub(crate) fn archive_name(
-        &mut self,
+        &self,
         package: &PkgType,
         target: &str,
         extension: &str,
@@ -189,11 +189,7 @@ impl Versions {
         }
     }
 
-    pub(crate) fn tarball_name(
-        &mut self,
-        package: &PkgType,
-        target: &str,
-    ) -> Result<String, Error> {
+    pub(crate) fn tarball_name(&self, package: &PkgType, target: &str) -> Result<String, Error> {
         self.archive_name(package, target, "tar.gz")
     }
 

From 52fdd2dd86af4b7dfa6b3aad63e5b5148b59c444 Mon Sep 17 00:00:00 2001
From: Eric Huss <eric@huss.org>
Date: Tue, 11 Jan 2022 17:01:00 -0800
Subject: [PATCH 07/26] Remove VERSION from manifest readme docs.

The version was removed in https://github.com/rust-lang/rust/pull/77145/
---
 src/tools/build-manifest/README.md | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/tools/build-manifest/README.md b/src/tools/build-manifest/README.md
index b77c5a907c118..44c96f31d0ba8 100644
--- a/src/tools/build-manifest/README.md
+++ b/src/tools/build-manifest/README.md
@@ -20,8 +20,7 @@ Then, you can generate the manifest and all the packages from `path/to/dist` to
 `path/to/output` with:
 
 ```
-$ cargo +nightly run path/to/dist path/to/output 1970-01-01 http://example.com \
-    CHANNEL VERSION
+$ cargo +nightly run path/to/dist path/to/output 1970-01-01 http://example.com CHANNEL
 ```
 
 Remember to replace `CHANNEL` with the channel you produced dist artifacts of

From 6a1099c2026dc224bdf53a17665cef563f10755a Mon Sep 17 00:00:00 2001
From: Eric Huss <eric@huss.org>
Date: Mon, 17 Jan 2022 20:18:56 -0800
Subject: [PATCH 08/26] Disable docs on aarch64-apple-darwin.

This builder is the slowest in the fleet. This should cut a considerable
amount of time. The manifest should now include the docs from
x86_64-apple-darwin. Although those docs are slightly different, it
should be close enough. When aarch64-apple-darwin heads towards tier 1,
we can revisit whether or not to re-enable the docs.
---
 .github/workflows/ci.yml     | 2 +-
 src/bootstrap/dist.rs        | 3 +--
 src/ci/github-actions/ci.yml | 1 +
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 67deb3d977942..fe5dedb6ba4b7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -320,7 +320,7 @@ jobs:
           - name: dist-aarch64-apple
             env:
               SCRIPT: "./x.py dist --stage 2"
-              RUST_CONFIGURE_ARGS: "--build=x86_64-apple-darwin --host=aarch64-apple-darwin --target=aarch64-apple-darwin --enable-full-tools --enable-sanitizers --enable-profiler --set rust.jemalloc --set llvm.ninja=false"
+              RUST_CONFIGURE_ARGS: "--build=x86_64-apple-darwin --host=aarch64-apple-darwin --target=aarch64-apple-darwin --enable-full-tools --enable-sanitizers --enable-profiler --disable-docs --set rust.jemalloc --set llvm.ninja=false"
               RUSTC_RETRY_LINKER_ON_SEGFAULT: 1
               USE_XCODE_CLANG: 1
               MACOSX_DEPLOYMENT_TARGET: 11.0
diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index 7d9b3da48ecb0..a46a4e63714c2 100644
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -1483,11 +1483,10 @@ impl Step for Extended {
             };
             prepare("rustc");
             prepare("cargo");
-            prepare("rust-docs");
             prepare("rust-std");
             prepare("rust-analysis");
             prepare("clippy");
-            for tool in &["rust-demangler", "rls", "rust-analyzer", "miri"] {
+            for tool in &["rust-docs", "rust-demangler", "rls", "rust-analyzer", "miri"] {
                 if built_tools.contains(tool) {
                     prepare(tool);
                 }
diff --git a/src/ci/github-actions/ci.yml b/src/ci/github-actions/ci.yml
index ac5d5822bfbd5..a70cdc4b519e6 100644
--- a/src/ci/github-actions/ci.yml
+++ b/src/ci/github-actions/ci.yml
@@ -496,6 +496,7 @@ jobs:
                 --enable-full-tools
                 --enable-sanitizers
                 --enable-profiler
+                --disable-docs
                 --set rust.jemalloc
                 --set llvm.ninja=false
               RUSTC_RETRY_LINKER_ON_SEGFAULT: 1

From fdb95f54e81532f5a620e79b8930f89e0e9aee80 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:02:49 -0800
Subject: [PATCH 09/26] Inline Printer's advance_right method

---
 compiler/rustc_ast_pretty/src/pp.rs | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index 25437f8b53a94..785125ccafcc5 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -290,7 +290,8 @@ impl Printer {
             self.right = self.left;
             self.buf.truncate(1);
         } else {
-            self.advance_right();
+            self.right += 1;
+            self.buf.advance_right();
         }
         self.scan_push(BufEntry { token: Token::Begin(b), size: -self.right_total });
     }
@@ -299,7 +300,8 @@ impl Printer {
         if self.scan_stack.is_empty() {
             self.print_end();
         } else {
-            self.advance_right();
+            self.right += 1;
+            self.buf.advance_right();
             self.scan_push(BufEntry { token: Token::End, size: -1 });
         }
     }
@@ -311,7 +313,8 @@ impl Printer {
             self.right = self.left;
             self.buf.truncate(1);
         } else {
-            self.advance_right();
+            self.right += 1;
+            self.buf.advance_right();
         }
         self.check_stack(0);
         self.scan_push(BufEntry { token: Token::Break(b), size: -self.right_total });
@@ -322,7 +325,8 @@ impl Printer {
         if self.scan_stack.is_empty() {
             self.print_string(s);
         } else {
-            self.advance_right();
+            self.right += 1;
+            self.buf.advance_right();
             let len = s.len() as isize;
             self.buf[self.right] = BufEntry { token: Token::String(s), size: len };
             self.right_total += len;
@@ -360,11 +364,6 @@ impl Printer {
         self.scan_stack.pop_back().unwrap()
     }
 
-    fn advance_right(&mut self) {
-        self.right += 1;
-        self.buf.advance_right();
-    }
-
     fn advance_left(&mut self) {
         let mut left_size = self.buf[self.left].size;
 

From e219b2b5f90bf48bf56533c16745f2ce85216a2c Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:04:12 -0800
Subject: [PATCH 10/26] Inline Printer's scan_push method

---
 compiler/rustc_ast_pretty/src/pp.rs | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index 785125ccafcc5..4f5140349c97b 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -293,7 +293,8 @@ impl Printer {
             self.right += 1;
             self.buf.advance_right();
         }
-        self.scan_push(BufEntry { token: Token::Begin(b), size: -self.right_total });
+        self.buf[self.right] = BufEntry { token: Token::Begin(b), size: -self.right_total };
+        self.scan_stack.push_front(self.right);
     }
 
     fn scan_end(&mut self) {
@@ -302,7 +303,8 @@ impl Printer {
         } else {
             self.right += 1;
             self.buf.advance_right();
-            self.scan_push(BufEntry { token: Token::End, size: -1 });
+            self.buf[self.right] = BufEntry { token: Token::End, size: -1 };
+            self.scan_stack.push_front(self.right);
         }
     }
 
@@ -317,7 +319,8 @@ impl Printer {
             self.buf.advance_right();
         }
         self.check_stack(0);
-        self.scan_push(BufEntry { token: Token::Break(b), size: -self.right_total });
+        self.buf[self.right] = BufEntry { token: Token::Break(b), size: -self.right_total };
+        self.scan_stack.push_front(self.right);
         self.right_total += b.blank_space;
     }
 
@@ -347,11 +350,6 @@ impl Printer {
         }
     }
 
-    fn scan_push(&mut self, entry: BufEntry) {
-        self.buf[self.right] = entry;
-        self.scan_stack.push_front(self.right);
-    }
-
     fn scan_pop(&mut self) -> usize {
         self.scan_stack.pop_front().unwrap()
     }

From 50d722a6917eb150362ff05e4881e63b3e7adc62 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:07:12 -0800
Subject: [PATCH 11/26] Simplify ring buffer pushes

---
 compiler/rustc_ast_pretty/src/pp.rs      | 11 ++++-------
 compiler/rustc_ast_pretty/src/pp/ring.rs |  8 ++++++++
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index 4f5140349c97b..43a3c792d4ac9 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -288,12 +288,11 @@ impl Printer {
             self.left_total = 1;
             self.right_total = 1;
             self.right = self.left;
-            self.buf.truncate(1);
+            self.buf.clear();
         } else {
             self.right += 1;
-            self.buf.advance_right();
         }
-        self.buf[self.right] = BufEntry { token: Token::Begin(b), size: -self.right_total };
+        self.buf.push(BufEntry { token: Token::Begin(b), size: -self.right_total });
         self.scan_stack.push_front(self.right);
     }
 
@@ -302,8 +301,7 @@ impl Printer {
             self.print_end();
         } else {
             self.right += 1;
-            self.buf.advance_right();
-            self.buf[self.right] = BufEntry { token: Token::End, size: -1 };
+            self.buf.push(BufEntry { token: Token::End, size: -1 });
             self.scan_stack.push_front(self.right);
         }
     }
@@ -329,9 +327,8 @@ impl Printer {
             self.print_string(s);
         } else {
             self.right += 1;
-            self.buf.advance_right();
             let len = s.len() as isize;
-            self.buf[self.right] = BufEntry { token: Token::String(s), size: len };
+            self.buf.push(BufEntry { token: Token::String(s), size: len });
             self.right_total += len;
             self.check_stream();
         }
diff --git a/compiler/rustc_ast_pretty/src/pp/ring.rs b/compiler/rustc_ast_pretty/src/pp/ring.rs
index 7e4e353ef1f8c..94bb10382f8af 100644
--- a/compiler/rustc_ast_pretty/src/pp/ring.rs
+++ b/compiler/rustc_ast_pretty/src/pp/ring.rs
@@ -22,6 +22,10 @@ impl<T> RingBuffer<T> {
         RingBuffer { data: VecDeque::new(), offset: 0 }
     }
 
+    pub fn push(&mut self, value: T) {
+        self.data.push_back(value);
+    }
+
     pub fn advance_right(&mut self)
     where
         T: Default,
@@ -34,6 +38,10 @@ impl<T> RingBuffer<T> {
         self.offset += 1;
     }
 
+    pub fn clear(&mut self) {
+        self.data.clear();
+    }
+
     pub fn truncate(&mut self, len: usize) {
         self.data.truncate(len);
     }

From e20d5abdfb39f38ac9f4919b053029ffb6560641 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:15:02 -0800
Subject: [PATCH 12/26] Inline Printer's scan_pop method

---
 compiler/rustc_ast_pretty/src/pp.rs | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index 43a3c792d4ac9..96d446e363804 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -347,10 +347,6 @@ impl Printer {
         }
     }
 
-    fn scan_pop(&mut self) -> usize {
-        self.scan_stack.pop_front().unwrap()
-    }
-
     fn scan_top(&self) -> usize {
         *self.scan_stack.front().unwrap()
     }
@@ -396,19 +392,19 @@ impl Printer {
             match self.buf[x].token {
                 Token::Begin(_) => {
                     if k > 0 {
-                        self.scan_pop();
+                        self.scan_stack.pop_front().unwrap();
                         self.buf[x].size += self.right_total;
                         self.check_stack(k - 1);
                     }
                 }
                 Token::End => {
                     // paper says + not =, but that makes no sense.
-                    self.scan_pop();
+                    self.scan_stack.pop_front().unwrap();
                     self.buf[x].size = 1;
                     self.check_stack(k + 1);
                 }
                 _ => {
-                    self.scan_pop();
+                    self.scan_stack.pop_front().unwrap();
                     self.buf[x].size += self.right_total;
                     if k > 0 {
                         self.check_stack(k);

From 2a14275500b5c9cddfab83bb606368a9a4192ea4 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:15:21 -0800
Subject: [PATCH 13/26] Inline Printer's scan_top method

---
 compiler/rustc_ast_pretty/src/pp.rs | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index 96d446e363804..4aeb4e4807b38 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -347,10 +347,6 @@ impl Printer {
         }
     }
 
-    fn scan_top(&self) -> usize {
-        *self.scan_stack.front().unwrap()
-    }
-
     fn scan_pop_bottom(&mut self) -> usize {
         self.scan_stack.pop_back().unwrap()
     }
@@ -388,7 +384,7 @@ impl Printer {
 
     fn check_stack(&mut self, k: usize) {
         if !self.scan_stack.is_empty() {
-            let x = self.scan_top();
+            let x = *self.scan_stack.front().unwrap();
             match self.buf[x].token {
                 Token::Begin(_) => {
                     if k > 0 {

From ae28ec5a9c09b0ea163ccdff26b5650d4d0ea3c0 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:15:38 -0800
Subject: [PATCH 14/26] Inline Printer's scan_pop_bottom method

---
 compiler/rustc_ast_pretty/src/pp.rs | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index 4aeb4e4807b38..e5542eda5961b 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -337,7 +337,7 @@ impl Printer {
     fn check_stream(&mut self) {
         if self.right_total - self.left_total > self.space {
             if Some(&self.left) == self.scan_stack.back() {
-                let scanned = self.scan_pop_bottom();
+                let scanned = self.scan_stack.pop_back().unwrap();
                 self.buf[scanned].size = SIZE_INFINITY;
             }
             self.advance_left();
@@ -347,10 +347,6 @@ impl Printer {
         }
     }
 
-    fn scan_pop_bottom(&mut self) -> usize {
-        self.scan_stack.pop_back().unwrap()
-    }
-
     fn advance_left(&mut self) {
         let mut left_size = self.buf[self.left].size;
 

From 80139a0f02ef04dc759f47ad59ece2138117c41c Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:18:04 -0800
Subject: [PATCH 15/26] Ensure Printer buf is always indexed using self.left or
 self.right

---
 compiler/rustc_ast_pretty/src/pp.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index e5542eda5961b..8d58eaa82a701 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -336,9 +336,9 @@ impl Printer {
 
     fn check_stream(&mut self) {
         if self.right_total - self.left_total > self.space {
-            if Some(&self.left) == self.scan_stack.back() {
-                let scanned = self.scan_stack.pop_back().unwrap();
-                self.buf[scanned].size = SIZE_INFINITY;
+            if self.scan_stack.back() == Some(&self.left) {
+                self.scan_stack.pop_back().unwrap();
+                self.buf[self.left].size = SIZE_INFINITY;
             }
             self.advance_left();
             if self.left != self.right {

From 947a09a4a88f97aa0ab59a5d21afd8ca3d429e60 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:18:47 -0800
Subject: [PATCH 16/26] Replace `if` + `unwrap` with `if let` in check_stack

---
 compiler/rustc_ast_pretty/src/pp.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index 8d58eaa82a701..b2870ac2734fa 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -379,8 +379,7 @@ impl Printer {
     }
 
     fn check_stack(&mut self, k: usize) {
-        if !self.scan_stack.is_empty() {
-            let x = *self.scan_stack.front().unwrap();
+        if let Some(&x) = self.scan_stack.front() {
             match self.buf[x].token {
                 Token::Begin(_) => {
                     if k > 0 {

From 0490e43422b3061ba3afef9b064a9360871d1455 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:19:18 -0800
Subject: [PATCH 17/26] Implement check_stream nonrecursively

---
 compiler/rustc_ast_pretty/src/pp.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index b2870ac2734fa..d32cc4694d3e5 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -335,14 +335,14 @@ impl Printer {
     }
 
     fn check_stream(&mut self) {
-        if self.right_total - self.left_total > self.space {
+        while self.right_total - self.left_total > self.space {
             if self.scan_stack.back() == Some(&self.left) {
                 self.scan_stack.pop_back().unwrap();
                 self.buf[self.left].size = SIZE_INFINITY;
             }
             self.advance_left();
-            if self.left != self.right {
-                self.check_stream();
+            if self.left == self.right {
+                break;
             }
         }
     }

From a37d272892172dfe598d9df182fa908d74359c6e Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:20:33 -0800
Subject: [PATCH 18/26] Implement check_stack nonrecursively

---
 compiler/rustc_ast_pretty/src/pp.rs | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index d32cc4694d3e5..dca0515a33033 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -378,27 +378,28 @@ impl Printer {
         }
     }
 
-    fn check_stack(&mut self, k: usize) {
-        if let Some(&x) = self.scan_stack.front() {
+    fn check_stack(&mut self, mut k: usize) {
+        while let Some(&x) = self.scan_stack.front() {
             match self.buf[x].token {
                 Token::Begin(_) => {
-                    if k > 0 {
-                        self.scan_stack.pop_front().unwrap();
-                        self.buf[x].size += self.right_total;
-                        self.check_stack(k - 1);
+                    if k == 0 {
+                        break;
                     }
+                    self.scan_stack.pop_front().unwrap();
+                    self.buf[x].size += self.right_total;
+                    k -= 1;
                 }
                 Token::End => {
                     // paper says + not =, but that makes no sense.
                     self.scan_stack.pop_front().unwrap();
                     self.buf[x].size = 1;
-                    self.check_stack(k + 1);
+                    k += 1;
                 }
                 _ => {
                     self.scan_stack.pop_front().unwrap();
                     self.buf[x].size += self.right_total;
-                    if k > 0 {
-                        self.check_stack(k);
+                    if k == 0 {
+                        break;
                     }
                 }
             }

From 377c9dbabfe6574ff0161f0fd8e750bb57181530 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:21:18 -0800
Subject: [PATCH 19/26] Index a single time in check_stack

---
 compiler/rustc_ast_pretty/src/pp.rs | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index dca0515a33033..d9832d560a841 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -380,24 +380,25 @@ impl Printer {
 
     fn check_stack(&mut self, mut k: usize) {
         while let Some(&x) = self.scan_stack.front() {
-            match self.buf[x].token {
+            let mut entry = &mut self.buf[x];
+            match entry.token {
                 Token::Begin(_) => {
                     if k == 0 {
                         break;
                     }
                     self.scan_stack.pop_front().unwrap();
-                    self.buf[x].size += self.right_total;
+                    entry.size += self.right_total;
                     k -= 1;
                 }
                 Token::End => {
                     // paper says + not =, but that makes no sense.
                     self.scan_stack.pop_front().unwrap();
-                    self.buf[x].size = 1;
+                    entry.size = 1;
                     k += 1;
                 }
                 _ => {
                     self.scan_stack.pop_front().unwrap();
-                    self.buf[x].size += self.right_total;
+                    entry.size += self.right_total;
                     if k == 0 {
                         break;
                     }

From fe5c4eab2dbc646f60f748b4b348acf5202ebf59 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:23:22 -0800
Subject: [PATCH 20/26] Eliminate a check_stack call on an empty scan stack

---
 compiler/rustc_ast_pretty/src/pp.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index d9832d560a841..21e685fff4a91 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -315,8 +315,8 @@ impl Printer {
         } else {
             self.right += 1;
             self.buf.advance_right();
+            self.check_stack(0);
         }
-        self.check_stack(0);
         self.buf[self.right] = BufEntry { token: Token::Break(b), size: -self.right_total };
         self.scan_stack.push_front(self.right);
         self.right_total += b.blank_space;

From 6e8b06015e7f0cfa05208c2d83e0a9140f62ab7a Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:24:17 -0800
Subject: [PATCH 21/26] Simplify the buffer push done by scan_break

---
 compiler/rustc_ast_pretty/src/pp.rs      | 7 +++----
 compiler/rustc_ast_pretty/src/pp/ring.rs | 4 ----
 2 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index 21e685fff4a91..b9b2f77431ef4 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -311,13 +311,12 @@ impl Printer {
             self.left_total = 1;
             self.right_total = 1;
             self.right = self.left;
-            self.buf.truncate(1);
+            self.buf.clear();
         } else {
-            self.right += 1;
-            self.buf.advance_right();
             self.check_stack(0);
+            self.right += 1;
         }
-        self.buf[self.right] = BufEntry { token: Token::Break(b), size: -self.right_total };
+        self.buf.push(BufEntry { token: Token::Break(b), size: -self.right_total });
         self.scan_stack.push_front(self.right);
         self.right_total += b.blank_space;
     }
diff --git a/compiler/rustc_ast_pretty/src/pp/ring.rs b/compiler/rustc_ast_pretty/src/pp/ring.rs
index 94bb10382f8af..62900ddfa2d46 100644
--- a/compiler/rustc_ast_pretty/src/pp/ring.rs
+++ b/compiler/rustc_ast_pretty/src/pp/ring.rs
@@ -41,10 +41,6 @@ impl<T> RingBuffer<T> {
     pub fn clear(&mut self) {
         self.data.clear();
     }
-
-    pub fn truncate(&mut self, len: usize) {
-        self.data.truncate(len);
-    }
 }
 
 impl<T> Index<usize> for RingBuffer<T> {

From cc66a7ff20d0c8626661fe6f53daab265537425f Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 19:59:36 -0800
Subject: [PATCH 22/26] Eliminate eof token state

---
 compiler/rustc_ast_pretty/src/pp.rs           | 51 +++++++++----------
 compiler/rustc_ast_pretty/src/pp/ring.rs      | 15 +++---
 compiler/rustc_ast_pretty/src/pprust/state.rs | 20 +++++---
 3 files changed, 44 insertions(+), 42 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index b9b2f77431ef4..0c9d4ef0e950d 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -167,14 +167,9 @@ pub enum Token {
     Break(BreakToken),
     Begin(BeginToken),
     End,
-    Eof,
 }
 
 impl Token {
-    crate fn is_eof(&self) -> bool {
-        matches!(self, Token::Eof)
-    }
-
     pub fn is_hardbreak_tok(&self) -> bool {
         matches!(self, Token::Break(BreakToken { offset: 0, blank_space: SIZE_INFINITY }))
     }
@@ -187,7 +182,6 @@ impl fmt::Display for Token {
             Token::Break(_) => f.write_str("BREAK"),
             Token::Begin(_) => f.write_str("BEGIN"),
             Token::End => f.write_str("END"),
-            Token::Eof => f.write_str("EOF"),
         }
     }
 }
@@ -233,6 +227,9 @@ pub struct Printer {
     print_stack: Vec<PrintStackElem>,
     /// Buffered indentation to avoid writing trailing whitespace
     pending_indentation: isize,
+    /// The token most recently popped from the left boundary of the
+    /// ring-buffer for printing
+    last_printed: Option<Token>,
 }
 
 #[derive(Clone)]
@@ -241,39 +238,36 @@ struct BufEntry {
     size: isize,
 }
 
-impl Default for BufEntry {
-    fn default() -> Self {
-        BufEntry { token: Token::Eof, size: 0 }
-    }
-}
-
 impl Printer {
     pub fn new() -> Self {
         let linewidth = 78;
-        let mut buf = RingBuffer::new();
-        buf.advance_right();
         Printer {
             out: String::new(),
             margin: linewidth as isize,
             space: linewidth as isize,
             left: 0,
             right: 0,
-            buf,
+            buf: RingBuffer::new(),
             left_total: 0,
             right_total: 0,
             scan_stack: VecDeque::new(),
             print_stack: Vec::new(),
             pending_indentation: 0,
+            last_printed: None,
         }
     }
 
-    pub fn last_token(&self) -> Token {
-        self.buf[self.right].token.clone()
+    pub fn last_token(&self) -> Option<&Token> {
+        self.last_token_still_buffered().or_else(|| self.last_printed.as_ref())
+    }
+
+    pub fn last_token_still_buffered(&self) -> Option<&Token> {
+        self.buf.last().map(|last| &last.token)
     }
 
     /// Be very careful with this!
-    pub fn replace_last_token(&mut self, t: Token) {
-        self.buf[self.right].token = t;
+    pub fn replace_last_token_still_buffered(&mut self, t: Token) {
+        self.buf.last_mut().unwrap().token = t;
     }
 
     fn scan_eof(&mut self) {
@@ -323,7 +317,7 @@ impl Printer {
 
     fn scan_string(&mut self, s: Cow<'static, str>) {
         if self.scan_stack.is_empty() {
-            self.print_string(s);
+            self.print_string(&s);
         } else {
             self.right += 1;
             let len = s.len() as isize;
@@ -459,7 +453,7 @@ impl Printer {
         }
     }
 
-    fn print_string(&mut self, s: Cow<'static, str>) {
+    fn print_string(&mut self, s: &str) {
         let len = s.len() as isize;
         // assert!(len <= space);
         self.space -= len;
@@ -473,21 +467,21 @@ impl Printer {
         self.out.reserve(self.pending_indentation as usize);
         self.out.extend(std::iter::repeat(' ').take(self.pending_indentation as usize));
         self.pending_indentation = 0;
-        self.out.push_str(&s);
+        self.out.push_str(s);
     }
 
     fn print(&mut self, token: Token, l: isize) {
-        match token {
-            Token::Begin(b) => self.print_begin(b, l),
+        match &token {
+            Token::Begin(b) => self.print_begin(*b, l),
             Token::End => self.print_end(),
-            Token::Break(b) => self.print_break(b, l),
+            Token::Break(b) => self.print_break(*b, l),
             Token::String(s) => {
                 let len = s.len() as isize;
                 assert_eq!(len, l);
                 self.print_string(s);
             }
-            Token::Eof => panic!(), // Eof should never get here.
         }
+        self.last_printed = Some(token);
     }
 
     // Convenience functions to talk to the printer.
@@ -542,7 +536,10 @@ impl Printer {
     }
 
     pub fn is_beginning_of_line(&self) -> bool {
-        self.last_token().is_eof() || self.last_token().is_hardbreak_tok()
+        match self.last_token() {
+            Some(last_token) => last_token.is_hardbreak_tok(),
+            None => true,
+        }
     }
 
     pub fn hardbreak_tok_offset(off: isize) -> Token {
diff --git a/compiler/rustc_ast_pretty/src/pp/ring.rs b/compiler/rustc_ast_pretty/src/pp/ring.rs
index 62900ddfa2d46..86b87614c1986 100644
--- a/compiler/rustc_ast_pretty/src/pp/ring.rs
+++ b/compiler/rustc_ast_pretty/src/pp/ring.rs
@@ -26,13 +26,6 @@ impl<T> RingBuffer<T> {
         self.data.push_back(value);
     }
 
-    pub fn advance_right(&mut self)
-    where
-        T: Default,
-    {
-        self.data.push_back(T::default());
-    }
-
     pub fn advance_left(&mut self) {
         self.data.pop_front().unwrap();
         self.offset += 1;
@@ -41,6 +34,14 @@ impl<T> RingBuffer<T> {
     pub fn clear(&mut self) {
         self.data.clear();
     }
+
+    pub fn last(&self) -> Option<&T> {
+        self.data.back()
+    }
+
+    pub fn last_mut(&mut self) -> Option<&mut T> {
+        self.data.back_mut()
+    }
 }
 
 impl<T> Index<usize> for RingBuffer<T> {
diff --git a/compiler/rustc_ast_pretty/src/pprust/state.rs b/compiler/rustc_ast_pretty/src/pprust/state.rs
index 17941058ed6f0..044f6b228dc0b 100644
--- a/compiler/rustc_ast_pretty/src/pprust/state.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/state.rs
@@ -329,9 +329,9 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
             CommentStyle::BlankLine => {
                 // We need to do at least one, possibly two hardbreaks.
                 let twice = match self.last_token() {
-                    pp::Token::String(s) => ";" == s,
-                    pp::Token::Begin(_) => true,
-                    pp::Token::End => true,
+                    Some(pp::Token::String(s)) => ";" == s,
+                    Some(pp::Token::Begin(_)) => true,
+                    Some(pp::Token::End) => true,
                     _ => false,
                 };
                 if twice {
@@ -687,11 +687,15 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
     fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
         if !self.is_beginning_of_line() {
             self.break_offset(n, off)
-        } else if off != 0 && self.last_token().is_hardbreak_tok() {
-            // We do something pretty sketchy here: tuck the nonzero
-            // offset-adjustment we were going to deposit along with the
-            // break into the previous hardbreak.
-            self.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
+        } else if off != 0 {
+            if let Some(last_token) = self.last_token_still_buffered() {
+                if last_token.is_hardbreak_tok() {
+                    // We do something pretty sketchy here: tuck the nonzero
+                    // offset-adjustment we were going to deposit along with the
+                    // break into the previous hardbreak.
+                    self.replace_last_token_still_buffered(pp::Printer::hardbreak_tok_offset(off));
+                }
+            }
         }
     }
 

From 4d3faae5cd34cc3a34a7c01fb2f22c68e092e0eb Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 18 Jan 2022 20:19:10 -0800
Subject: [PATCH 23/26] Eliminate left and right cursors in favor of ring
 buffer

---
 compiler/rustc_ast_pretty/src/pp.rs      | 43 ++++++++----------------
 compiler/rustc_ast_pretty/src/pp/ring.rs | 20 ++++++++++-
 2 files changed, 33 insertions(+), 30 deletions(-)

diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index 0c9d4ef0e950d..bdd70148d85a0 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -206,10 +206,6 @@ pub struct Printer {
     margin: isize,
     /// Number of spaces left on line
     space: isize,
-    /// Index of left side of input stream
-    left: usize,
-    /// Index of right side of input stream
-    right: usize,
     /// Ring-buffer of tokens and calculated sizes
     buf: RingBuffer<BufEntry>,
     /// Running size of stream "...left"
@@ -245,8 +241,6 @@ impl Printer {
             out: String::new(),
             margin: linewidth as isize,
             space: linewidth as isize,
-            left: 0,
-            right: 0,
             buf: RingBuffer::new(),
             left_total: 0,
             right_total: 0,
@@ -281,22 +275,18 @@ impl Printer {
         if self.scan_stack.is_empty() {
             self.left_total = 1;
             self.right_total = 1;
-            self.right = self.left;
             self.buf.clear();
-        } else {
-            self.right += 1;
         }
-        self.buf.push(BufEntry { token: Token::Begin(b), size: -self.right_total });
-        self.scan_stack.push_front(self.right);
+        let right = self.buf.push(BufEntry { token: Token::Begin(b), size: -self.right_total });
+        self.scan_stack.push_front(right);
     }
 
     fn scan_end(&mut self) {
         if self.scan_stack.is_empty() {
             self.print_end();
         } else {
-            self.right += 1;
-            self.buf.push(BufEntry { token: Token::End, size: -1 });
-            self.scan_stack.push_front(self.right);
+            let right = self.buf.push(BufEntry { token: Token::End, size: -1 });
+            self.scan_stack.push_front(right);
         }
     }
 
@@ -304,14 +294,12 @@ impl Printer {
         if self.scan_stack.is_empty() {
             self.left_total = 1;
             self.right_total = 1;
-            self.right = self.left;
             self.buf.clear();
         } else {
             self.check_stack(0);
-            self.right += 1;
         }
-        self.buf.push(BufEntry { token: Token::Break(b), size: -self.right_total });
-        self.scan_stack.push_front(self.right);
+        let right = self.buf.push(BufEntry { token: Token::Break(b), size: -self.right_total });
+        self.scan_stack.push_front(right);
         self.right_total += b.blank_space;
     }
 
@@ -319,7 +307,6 @@ impl Printer {
         if self.scan_stack.is_empty() {
             self.print_string(&s);
         } else {
-            self.right += 1;
             let len = s.len() as isize;
             self.buf.push(BufEntry { token: Token::String(s), size: len });
             self.right_total += len;
@@ -329,22 +316,22 @@ impl Printer {
 
     fn check_stream(&mut self) {
         while self.right_total - self.left_total > self.space {
-            if self.scan_stack.back() == Some(&self.left) {
+            if *self.scan_stack.back().unwrap() == self.buf.index_of_first() {
                 self.scan_stack.pop_back().unwrap();
-                self.buf[self.left].size = SIZE_INFINITY;
+                self.buf.first_mut().unwrap().size = SIZE_INFINITY;
             }
             self.advance_left();
-            if self.left == self.right {
+            if self.buf.is_empty() {
                 break;
             }
         }
     }
 
     fn advance_left(&mut self) {
-        let mut left_size = self.buf[self.left].size;
+        let mut left_size = self.buf.first().unwrap().size;
 
         while left_size >= 0 {
-            let left = self.buf[self.left].token.clone();
+            let left = self.buf.first().unwrap().token.clone();
 
             let len = match left {
                 Token::Break(b) => b.blank_space,
@@ -360,14 +347,12 @@ impl Printer {
 
             self.left_total += len;
 
-            if self.left == self.right {
+            self.buf.advance_left();
+            if self.buf.is_empty() {
                 break;
             }
 
-            self.buf.advance_left();
-            self.left += 1;
-
-            left_size = self.buf[self.left].size;
+            left_size = self.buf.first().unwrap().size;
         }
     }
 
diff --git a/compiler/rustc_ast_pretty/src/pp/ring.rs b/compiler/rustc_ast_pretty/src/pp/ring.rs
index 86b87614c1986..d20142eb591fe 100644
--- a/compiler/rustc_ast_pretty/src/pp/ring.rs
+++ b/compiler/rustc_ast_pretty/src/pp/ring.rs
@@ -22,8 +22,14 @@ impl<T> RingBuffer<T> {
         RingBuffer { data: VecDeque::new(), offset: 0 }
     }
 
-    pub fn push(&mut self, value: T) {
+    pub fn is_empty(&self) -> bool {
+        self.data.is_empty()
+    }
+
+    pub fn push(&mut self, value: T) -> usize {
+        let index = self.offset + self.data.len();
         self.data.push_back(value);
+        index
     }
 
     pub fn advance_left(&mut self) {
@@ -35,6 +41,18 @@ impl<T> RingBuffer<T> {
         self.data.clear();
     }
 
+    pub fn index_of_first(&self) -> usize {
+        self.offset
+    }
+
+    pub fn first(&self) -> Option<&T> {
+        self.data.front()
+    }
+
+    pub fn first_mut(&mut self) -> Option<&mut T> {
+        self.data.front_mut()
+    }
+
     pub fn last(&self) -> Option<&T> {
         self.data.back()
     }

From 48f5dcad104dd4dd58b8852cb6147abb4179b3b1 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume.gomez@huawei.com>
Date: Mon, 17 Jan 2022 17:36:39 +0100
Subject: [PATCH 24/26] Move back templates into html folder

---
 Cargo.lock                                          | 2 ++
 src/librustdoc/Cargo.toml                           | 2 +-
 src/librustdoc/askama.toml                          | 2 ++
 src/librustdoc/{ => html}/templates/STYLE.md        | 0
 src/librustdoc/{ => html}/templates/page.html       | 0
 src/librustdoc/{ => html}/templates/print_item.html | 0
 6 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 src/librustdoc/askama.toml
 rename src/librustdoc/{ => html}/templates/STYLE.md (100%)
 rename src/librustdoc/{ => html}/templates/page.html (100%)
 rename src/librustdoc/{ => html}/templates/print_item.html (100%)

diff --git a/Cargo.lock b/Cargo.lock
index 73ffd3e044eb3..a7496e61b8beb 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -152,7 +152,9 @@ dependencies = [
  "nom",
  "proc-macro2",
  "quote",
+ "serde",
  "syn",
+ "toml",
 ]
 
 [[package]]
diff --git a/src/librustdoc/Cargo.toml b/src/librustdoc/Cargo.toml
index ccb844cd10b25..67d167e86df7f 100644
--- a/src/librustdoc/Cargo.toml
+++ b/src/librustdoc/Cargo.toml
@@ -8,7 +8,7 @@ path = "lib.rs"
 
 [dependencies]
 arrayvec = { version = "0.7", default-features = false }
-askama = { version = "0.11", default-features = false }
+askama = { version = "0.11", default-features = false, features = ["config"] }
 atty = "0.2"
 pulldown-cmark = { version = "0.9", default-features = false }
 minifier = "0.0.41"
diff --git a/src/librustdoc/askama.toml b/src/librustdoc/askama.toml
new file mode 100644
index 0000000000000..0c984f637ba29
--- /dev/null
+++ b/src/librustdoc/askama.toml
@@ -0,0 +1,2 @@
+[general]
+dirs = ["html/templates"]
diff --git a/src/librustdoc/templates/STYLE.md b/src/librustdoc/html/templates/STYLE.md
similarity index 100%
rename from src/librustdoc/templates/STYLE.md
rename to src/librustdoc/html/templates/STYLE.md
diff --git a/src/librustdoc/templates/page.html b/src/librustdoc/html/templates/page.html
similarity index 100%
rename from src/librustdoc/templates/page.html
rename to src/librustdoc/html/templates/page.html
diff --git a/src/librustdoc/templates/print_item.html b/src/librustdoc/html/templates/print_item.html
similarity index 100%
rename from src/librustdoc/templates/print_item.html
rename to src/librustdoc/html/templates/print_item.html

From 4bd571c4ffc3ce14a3584bd11e3f1f4883b2bff6 Mon Sep 17 00:00:00 2001
From: lcnr <rust@lcnr.de>
Date: Wed, 19 Jan 2022 10:33:23 +0100
Subject: [PATCH 25/26] remove `is_noop`

---
 compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs      | 2 +-
 compiler/rustc_middle/src/ty/subst.rs                       | 4 ----
 compiler/rustc_trait_selection/src/traits/specialize/mod.rs | 2 +-
 compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs            | 4 ++--
 4 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs b/compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs
index f4703b22ecbcf..55c9b4d9ba12d 100644
--- a/compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs
+++ b/compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs
@@ -90,7 +90,7 @@ macro call_intrinsic_match {
         match $intrinsic {
             $(
                 sym::$name => {
-                    assert!($substs.is_noop());
+                    assert!($substs.is_empty());
                     if let [$(ref $arg),*] = *$args {
                         let ($($arg,)*) = (
                             $(codegen_operand($fx, $arg),)*
diff --git a/compiler/rustc_middle/src/ty/subst.rs b/compiler/rustc_middle/src/ty/subst.rs
index ab33fbcca15a3..63e9b58584c5f 100644
--- a/compiler/rustc_middle/src/ty/subst.rs
+++ b/compiler/rustc_middle/src/ty/subst.rs
@@ -275,10 +275,6 @@ impl<'a, 'tcx> InternalSubsts<'tcx> {
         }
     }
 
-    pub fn is_noop(&self) -> bool {
-        self.is_empty()
-    }
-
     #[inline]
     pub fn types(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
         self.iter()
diff --git a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
index cd2e0f18e0cc0..195a4a4a653e1 100644
--- a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
@@ -484,7 +484,7 @@ crate fn to_pretty_impl_header(tcx: TyCtxt<'_>, impl_def_id: DefId) -> Option<St
     let mut types_without_default_bounds = FxHashSet::default();
     let sized_trait = tcx.lang_items().sized_trait();
 
-    if !substs.is_noop() {
+    if !substs.is_empty() {
         types_without_default_bounds.extend(substs.types());
         w.push('<');
         w.push_str(
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
index a031f802b6d98..f01b826781748 100644
--- a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
@@ -182,7 +182,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // `foo.bar::<u32>(...)` -- the `Self` type here will be the
         // type of `foo` (possibly adjusted), but we don't want to
         // include that. We want just the `[_, u32]` part.
-        if !method.substs.is_noop() {
+        if !method.substs.is_empty() {
             let method_generics = self.tcx.generics_of(method.def_id);
             if !method_generics.params.is_empty() {
                 let user_type_annotation = self.infcx.probe(|_| {
@@ -211,7 +211,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     }
 
     pub fn write_substs(&self, node_id: hir::HirId, substs: SubstsRef<'tcx>) {
-        if !substs.is_noop() {
+        if !substs.is_empty() {
             debug!("write_substs({:?}, {:?}) in fcx {}", node_id, substs, self.tag());
 
             self.typeck_results.borrow_mut().node_substs_mut().insert(node_id, substs);

From c8e6889e08fd3a707134a3089840a01e615c1551 Mon Sep 17 00:00:00 2001
From: Eric Huss <eric@huss.org>
Date: Wed, 19 Jan 2022 09:41:04 -0800
Subject: [PATCH 26/26] Add assert that fallback targets must be available.

---
 src/tools/build-manifest/src/main.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/tools/build-manifest/src/main.rs b/src/tools/build-manifest/src/main.rs
index d3bce6b3e8df5..6b56d6bc4adf0 100644
--- a/src/tools/build-manifest/src/main.rs
+++ b/src/tools/build-manifest/src/main.rs
@@ -536,7 +536,10 @@ impl Builder {
             }
             for (substr, fallback_target) in fallback {
                 if target_name.contains(substr) {
-                    return Target::from_compressed_tar(self, &tarball_name!(fallback_target));
+                    let t = Target::from_compressed_tar(self, &tarball_name!(fallback_target));
+                    // Fallbacks must always be available.
+                    assert!(t.available);
+                    return t;
                 }
             }
             Target::unavailable()