!15 Update to 1.51.0

From: @wang_yue111 Reviewed-by: @maminjie,@small_leek Signed-off-by: @small_leek
2021-05-10 15:57:09 +08:00 · 2021-05-10 15:57:09 +08:00 · 9cce0cbcab
commit 9cce0cbcab
parent 23a0d9665b 1927bf08e4
13 changed files with 944 additions and 35 deletions
--- a/0001-Revert-Auto-merge-of-79547.patch
+++ b/0001-Revert-Auto-merge-of-79547.patch
@ -0,0 +1,102 @@
+From eaf7ea1fc339e1ff348ed941ed2e8c4d66f3e458 Mon Sep 17 00:00:00 2001
+From: Josh Stone <jistone@redhat.com>
+Date: Thu, 18 Feb 2021 19:14:58 -0800
+Subject: [PATCH] Revert "Auto merge of #79547 - erikdesjardins:byval,
+ r=nagisa"
+
+This reverts commit a094ff9590b83c8f94d898f92c2964a5803ded06, reversing
+changes made to d37afad0cc87bf709ad10c85319296ac53030f03.
+---
+ compiler/rustc_middle/src/ty/layout.rs               | 12 ++++++------
+ ...return-value-in-reg.rs => return-value-in-reg.rs} |  4 ++--
+ src/test/codegen/union-abi.rs                        | 11 +++--------
+ 3 files changed, 11 insertions(+), 16 deletions(-)
+ rename src/test/codegen/{arg-return-value-in-reg.rs => return-value-in-reg.rs} (74%)
+
+diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
+index b545b92c9252..545f6aee1a21 100644
+--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
+@@ -2849,7 +2849,7 @@ fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi) {
+             || abi == SpecAbi::RustIntrinsic
+             || abi == SpecAbi::PlatformIntrinsic
+         {
+-            let fixup = |arg: &mut ArgAbi<'tcx, Ty<'tcx>>| {
+            let fixup = |arg: &mut ArgAbi<'tcx, Ty<'tcx>>, is_ret: bool| {
+                 if arg.is_ignore() {
+                     return;
+                 }
+@@ -2887,9 +2887,9 @@ fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi) {
+                     _ => return,
+                 }
+ 
+-                // Pass and return structures up to 2 pointers in size by value, matching `ScalarPair`.
+-                // LLVM will usually pass these in 2 registers, which is more efficient than by-ref.
+-                let max_by_val_size = Pointer.size(cx) * 2;
+                // Return structures up to 2 pointers in size by value, matching `ScalarPair`. LLVM
+                // will usually return these in 2 registers, which is more efficient than by-ref.
+                let max_by_val_size = if is_ret { Pointer.size(cx) * 2 } else { Pointer.size(cx) };
+                 let size = arg.layout.size;
+ 
+                 if arg.layout.is_unsized() || size > max_by_val_size {
+@@ -2901,9 +2901,9 @@ fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi) {
+                     arg.cast_to(Reg { kind: RegKind::Integer, size });
+                 }
+             };
+-            fixup(&mut self.ret);
+            fixup(&mut self.ret, true);
+             for arg in &mut self.args {
+-                fixup(arg);
+                fixup(arg, false);
+             }
+             return;
+         }
+diff --git a/src/test/codegen/arg-return-value-in-reg.rs b/src/test/codegen/return-value-in-reg.rs
+similarity index 74%
+rename from src/test/codegen/arg-return-value-in-reg.rs
+rename to src/test/codegen/return-value-in-reg.rs
+index a69291d47821..4bc0136c5e32 100644
+--- a/src/test/codegen/arg-return-value-in-reg.rs
+++ b/src/test/codegen/return-value-in-reg.rs
+@@ -1,4 +1,4 @@
+-//! Check that types of up to 128 bits are passed and returned by-value instead of via pointer.
+//! This test checks that types of up to 128 bits are returned by-value instead of via out-pointer.
+ 
+ // compile-flags: -C no-prepopulate-passes -O
+ // only-x86_64
+@@ -11,7 +11,7 @@ pub struct S {
+     c: u32,
+ }
+ 
+-// CHECK: define i128 @modify(i128{{( %0)?}})
+// CHECK: define i128 @modify(%S* noalias nocapture dereferenceable(16) %s)
+ #[no_mangle]
+ pub fn modify(s: S) -> S {
+     S { a: s.a + s.a, b: s.b + s.b, c: s.c + s.c }
+diff --git a/src/test/codegen/union-abi.rs b/src/test/codegen/union-abi.rs
+index f282fd237054..afea01e9a2d0 100644
+--- a/src/test/codegen/union-abi.rs
+++ b/src/test/codegen/union-abi.rs
+@@ -63,16 +63,11 @@ pub union UnionU128{a:u128}
+ #[no_mangle]
+ pub fn test_UnionU128(_: UnionU128) -> UnionU128 { loop {} }
+ 
+-pub union UnionU128x2{a:(u128, u128)}
+-// CHECK: define void @test_UnionU128x2(i128 %_1.0, i128 %_1.1)
+-#[no_mangle]
+-pub fn test_UnionU128x2(_: UnionU128x2) { loop {} }
+-
+ #[repr(C)]
+-pub union CUnionU128x2{a:(u128, u128)}
+-// CHECK: define void @test_CUnionU128x2(%CUnionU128x2* {{.*}} %_1)
+pub union CUnionU128{a:u128}
+// CHECK: define void @test_CUnionU128(%CUnionU128* {{.*}} %_1)
+ #[no_mangle]
+-pub fn test_CUnionU128x2(_: CUnionU128x2) { loop {} }
+pub fn test_CUnionU128(_: CUnionU128) { loop {} }
+ 
+ pub union UnionBool { b:bool }
+ // CHECK: define zeroext i1 @test_UnionBool(i8 %b)
+-- 
+2.29.2
+
--- a/rust.spec
+++ b/rust.spec
@ -1,23 +1,40 @@
+%global rust_arches x86_64 i686 armv7hl aarch64 ppc64 ppc64le s390x
 %{!?channel: %global channel stable}
-%global bootstrap_rust 1.44.0
-%global bootstrap_cargo 1.44.0
-%global bootstrap_channel 1.44.0
-%global bootstrap_date 2020-06-04
+%global bootstrap_rust 1.50.0
+%global bootstrap_cargo 1.50.0
+%global bootstrap_channel 1.50.0
+%global bootstrap_date 2021-02-11
 %bcond_with llvm_static
 %bcond_with bundled_llvm
 %bcond_without bundled_libgit2
+%bcond_with disabled_libssh2
+%bcond_without curl_http2
+%bcond_without lldb
 Name:                rust
-Version:             1.45.2
+Version:             1.51.0
 Release:             1
 Summary:             The Rust Programming Language
 License:             (ASL 2.0 or MIT) and (BSD and MIT)
 URL:                 https://www.rust-lang.org
+ExclusiveArch:       %{rust_arches}
 %if "%{channel}" == "stable"
 %global rustc_package rustc-%{version}-src
 %else
 %global rustc_package rustc-%{channel}-src
 %endif
 Source0:             https://static.rust-lang.org/dist/%{rustc_package}.tar.xz
+Source1:             rustc-%{version}-src.tar.xz.aa
+Source2:             rustc-%{version}-src.tar.xz.ab
+
+Patch0001:           0001-Revert-Auto-merge-of-79547.patch
+Patch0002:           rustc-1.51.0-backport-pr81741.patch
+Patch0003:           rustc-1.51.0-backport-pr82289.patch
+Patch0004:           rustc-1.51.0-backport-pr82292.patch
+Patch0005:           rustc-1.51.0-backport-pr81910.patch
+Patch0006:           rustc-1.51.0-backport-pr81728.patch
+Patch0007:           rustc-1.51.0-backport-pr83629.patch
+Patch0008:           rustc-1.48.0-disable-libssh2.patch
+Patch0009:           rustc-1.51.0-disable-http2.patch
 %{lua: function rust_triple(arch)
  local abi = "gnu"
  if arch == "armv7hl" then
@ -27,6 +44,8 @@ Source0:             https://static.rust-lang.org/dist/%{rustc_package}.tar.xz
    arch = "powerpc64"
  elseif arch == "ppc64le" then
    arch = "powerpc64le"
+  elseif arch == "riscv64" then
+    arch = "riscv64gc"
  end
  return arch.."-unknown-linux-"..abi
 end}
@ -58,13 +77,13 @@ BuildRequires:       cargo >= %{bootstrap_cargo}
 BuildRequires:       (%{name} >= %{bootstrap_rust} with %{name} <= %{version})
 %global local_rust_root %{_prefix}
 %endif
-BuildRequires:       make gcc gcc-c++ ncurses-devel curl pkgconfig(libcurl) pkgconfig(liblzma)
+BuildRequires:       make gcc gcc-c++ ncurses-devel curl curl-devel pkgconfig(libcurl) pkgconfig(liblzma)
 BuildRequires:       pkgconfig(openssl) pkgconfig(zlib) pkgconfig(libssh2) >= 1.6.0
 %global python python3
 BuildRequires:       %{python}
 %if %with bundled_llvm
 BuildRequires:       cmake3 >= 3.4.3
-Provides:            bundled(llvm) = 10.0.1
+Provides:            bundled(llvm) = 11.0.1
 %else
 BuildRequires:       cmake >= 2.8.11
 %if %defined llvm
@ -73,13 +92,12 @@ BuildRequires:       cmake >= 2.8.11
 %global llvm llvm
 %global llvm_root %{_prefix}
 %endif
-BuildRequires:       %{llvm}-devel >= 8.0
+BuildRequires:       %{llvm}-devel >= 9.0
 %if %with llvm_static
 BuildRequires:       %{llvm}-static libffi-devel
 %endif
 %endif
 BuildRequires:       procps-ng gdb
-Provides:            bundled(libbacktrace) = 1.0.20200219
 Provides:            rustc = %{version}-%{release}
 Provides:            rustc%{?_isa} = %{version}-%{release}
 Requires:            %{name}-std-static%{?_isa} = %{version}-%{release}
@ -124,8 +142,9 @@ programs.
 %package lldb
 Summary:             LLDB pretty printers for Rust
 BuildArch:           noarch
-Requires:            lldb python3-lldb
+Requires:            lldb %{python}-lldb
 Requires:            %{name}-debugger-common = %{version}-%{release}
+
 %description lldb
 This package includes the rust-lldb script, which allows easier debugging of Rust
 programs.
@ -138,7 +157,9 @@ its standard library.

 %package -n cargo
 Summary:             Rust's package manager and build tool
-Provides:            bundled(libgit2) = 1.0.0
+%if %with bundled_libgit2
+Provides:            bundled(libgit2) = 1.1.0
+%endif
 BuildRequires:       git
 Requires:            rust
 Obsoletes:           cargo-vendor <= 0.1.23
@ -164,7 +185,9 @@ A tool for formatting Rust code according to style guidelines.

 %package -n rls
 Summary:             Rust Language Server for IDE integration
-Provides:            bundled(libgit2) = 1.0.0
+%if %with bundled_libgit2
+Provides:            bundled(libgit2) = 1.1.0
+%endif
 Requires:            rust-analysis %{name}%{?_isa} = %{version}-%{release}
 Obsoletes:           rls-preview < 1.31.6
 Provides:            rls-preview = %{version}-%{release}
@ -198,6 +221,10 @@ feature for the Rust standard library. The RLS (Rust Language Server) uses this
 data to provide information about the Rust standard library.

 %prep
+cd ../SOURCES
+cat %{SOURCE1} %{SOURCE2} | tar xJ
+cd ..
+
 %ifarch %{bootstrap_arches}
 %setup -q -n %{bootstrap_root} -T -b %{bootstrap_source}
 ./install.sh --components=cargo,rustc,rust-std-%{rust_triple} \
@ -206,20 +233,41 @@ test -f '%{local_rust_root}/bin/cargo'
 test -f '%{local_rust_root}/bin/rustc'
 %endif
 %setup -q -n %{rustc_package}
-%if "%{python}" == "python3"
-sed -i.try-py3 -e '/try python2.7/i try python3 "$@"' ./configure
+%patch0001 -p1
+%patch0002 -p1
+%patch0003 -p1
+%patch0004 -p1
+%patch0005 -p1
+%patch0006 -p1
+%patch0007 -p1
+%if %with disabled_libssh2
+%patch0008 -p1
+%endif
+%if %without curl_http2
+%patch0009 -p1
+rm -rf vendor/libnghttp2-sys/
+%endif
+%if "%{python}" != "python3"
+sed -i.try-python -e '/^try python3 /i try "%{python}" "$@"' ./configure
 %endif
 %if %without bundled_llvm
 rm -rf src/llvm-project/
+mkdir -p src/llvm-project/libunwind/
 %endif
 rm -rf vendor/curl-sys/curl/
 rm -rf vendor/jemalloc-sys/jemalloc/
+rm -rf vendor/libssh2-sys/libssh2/
 rm -rf vendor/libz-sys/src/zlib/
+rm -rf vendor/libz-sys/src/zlib-ng/
 rm -rf vendor/lzma-sys/xz-*/
 rm -rf vendor/openssl-src/openssl/
-rm -rf vendor/libssh2-sys/libssh2/
+%if %without bundled_libgit2
+rm -rf vendor/libgit2-sys/libgit2/
+%endif
+%if %with disabled_libssh2
+rm -rf vendor/libssh2-sys/
+%endif
 sed -i.lzma -e '/LZMA_API_STATIC/d' src/bootstrap/tool.rs
-cp -a vendor/backtrace-sys/src/libbacktrace/LICENSE{,-libbacktrace}
 %if %{without bundled_llvm} && %{with llvm_static}
 sed -i.ffi -e '$a #[link(name = "ffi")] extern {}' \
  src/librustc_llvm/lib.rs
@ -227,11 +275,19 @@ sed -i.ffi -e '$a #[link(name = "ffi")] extern {}' \
 find vendor -name .cargo-checksum.json \
  -exec sed -i.uncheck -e 's/"files":{[^}]*}/"files":{ }/' '{}' '+'
 find -name '*.rs' -type f -perm /111 -exec chmod -v -x '{}' '+'
+%global rust_env RUSTFLAGS="%{rustflags}"
+%if 0%{?cmake_path:1}
+%global rust_env %{rust_env} PATH="%{cmake_path}:$PATH"
+%endif
+%if %without bundled_libgit2
+%global rust_env %{rust_env} LIBGIT2_SYS_USE_PKG_CONFIG=1
+%endif
+%if %without disabled_libssh2
+%global rust_env %{rust_env} LIBSSH2_SYS_USE_PKG_CONFIG=1
+%endif

 %build
-export LIBSSH2_SYS_USE_PKG_CONFIG=1
-%{?cmake_path:export PATH=%{cmake_path}:$PATH}
-%{?rustflags:export RUSTFLAGS="%{rustflags}"}
+export %{rust_env}
 %global common_libdir %{_prefix}/lib
 %global rustlibdir %{common_libdir}/rustlib
 %ifarch %{arm} %{ix86} s390x
@ -242,6 +298,11 @@ export LIBSSH2_SYS_USE_PKG_CONFIG=1
 %ifnarch %{power64}
 %define codegen_units_std --set rust.codegen-units-std=1
 %endif
+ncpus=$(/usr/bin/getconf _NPROCESSORS_ONLN)
+max_cpus=$(( ($(free -g | awk '/^Mem:/{print $2}') + 1) / 2 ))
+if [ "$max_cpus" -ge 1 -a "$max_cpus" -lt "$ncpus" ]; then
+  ncpus="$max_cpus"
+fi
 %configure --disable-option-checking \
  --libdir=%{common_libdir} \
  --build=%{rust_triple} --host=%{rust_triple} --target=%{rust_triple} \
@ -258,12 +319,11 @@ export LIBSSH2_SYS_USE_PKG_CONFIG=1
  --enable-verbose-tests \
  %{?codegen_units_std} \
  --release-channel=%{channel}
-%{python} ./x.py build
-%{python} ./x.py doc
+%{python} ./x.py build -j "$ncpus" --stage 2
+%{python} ./x.py doc --stage 2

 %install
-%{?cmake_path:export PATH=%{cmake_path}:$PATH}
-%{?rustflags:export RUSTFLAGS="%{rustflags}"}
+export %{rust_env}
 DESTDIR=%{buildroot} %{python} ./x.py install
 %if "%{_libdir}" != "%{common_libdir}"
 mkdir -p %{buildroot}%{_libdir}
@ -296,20 +356,23 @@ find %{buildroot}%{_docdir}/%{name}/html -type f -exec chmod -x '{}' '+'
 mkdir -p %{buildroot}%{_datadir}/cargo/registry
 mkdir -p %{buildroot}%{_docdir}/cargo
 ln -sT ../rust/html/cargo/ %{buildroot}%{_docdir}/cargo/html
+%if %without lldb
+rm -f %{buildroot}%{_bindir}/rust-lldb
+rm -f %{buildroot}%{rustlibdir}/etc/lldb_*
+%endif
+rm -f %{buildroot}%{rustlibdir}/%{rust_triple}/bin/rust-ll*

 %check
-%{?cmake_path:export PATH=%{cmake_path}:$PATH}
-%{?rustflags:export RUSTFLAGS="%{rustflags}"}
-%{python} ./x.py test --no-fail-fast || :
-%{python} ./x.py test --no-fail-fast cargo || :
-%{python} ./x.py test --no-fail-fast clippy || :
-%{python} ./x.py test --no-fail-fast rls || :
-%{python} ./x.py test --no-fail-fast rustfmt || :
+export %{rust_env}
+%{python} ./x.py test --no-fail-fast --stage 2 || :
+%{python} ./x.py test --no-fail-fast --stage 2 cargo || :
+%{python} ./x.py test --no-fail-fast --stage 2 clippy || :
+%{python} ./x.py test --no-fail-fast --stage 2 rls || :
+%{python} ./x.py test --no-fail-fast --stage 2 rustfmt || :
 %ldconfig_scriptlets

 %files
 %license COPYRIGHT LICENSE-APACHE LICENSE-MIT
-%license vendor/backtrace-sys/src/libbacktrace/LICENSE-libbacktrace
 %doc README.md
 %{_bindir}/rustc
 %{_bindir}/rustdoc
@ -330,16 +393,18 @@ ln -sT ../rust/html/cargo/ %{buildroot}%{_docdir}/cargo/html
 %files debugger-common
 %dir %{rustlibdir}
 %dir %{rustlibdir}/etc
-%{rustlibdir}/etc/debugger_*.py*
+%{rustlibdir}/etc/rust_*.py*

 %files gdb
 %{_bindir}/rust-gdb
-%{rustlibdir}/etc/gdb_*.py*
+%{rustlibdir}/etc/gdb_*
 %exclude %{_bindir}/rust-gdbgui
+%if %with lldb

 %files lldb
 %{_bindir}/rust-lldb
-%{rustlibdir}/etc/lldb_*.py*
+%{rustlibdir}/etc/lldb_*
+%endif

 %files doc
 %docdir %{_docdir}/%{name}
@ -348,7 +413,6 @@ ln -sT ../rust/html/cargo/ %{buildroot}%{_docdir}/cargo/html
 %{_docdir}/%{name}/html/*/
 %{_docdir}/%{name}/html/*.html
 %{_docdir}/%{name}/html/*.css
-%{_docdir}/%{name}/html/*.ico
 %{_docdir}/%{name}/html/*.js
 %{_docdir}/%{name}/html/*.png
 %{_docdir}/%{name}/html/*.svg
@ -360,6 +424,7 @@ ln -sT ../rust/html/cargo/ %{buildroot}%{_docdir}/cargo/html
 %license src/tools/cargo/LICENSE-APACHE src/tools/cargo/LICENSE-MIT src/tools/cargo/LICENSE-THIRD-PARTY
 %doc src/tools/cargo/README.md
 %{_bindir}/cargo
+%{_libexecdir}/cargo*
 %{_mandir}/man1/cargo*.1*
 %{_sysconfdir}/bash_completion.d/cargo
 %{_datadir}/zsh/site-functions/_cargo
@ -396,6 +461,9 @@ ln -sT ../rust/html/cargo/ %{buildroot}%{_docdir}/cargo/html
 %{rustlibdir}/%{rust_triple}/analysis/

 %changelog
+* Fri May 07 2021 wangyue <wangyue92@huawei.com> - 1.51.0-1
+- Update to 1.51.0
+
 * Mon Aug 17 2020 zhangjiapeng <zhangjiapeng9@huawei.com> - 1.45.2-1
 - Update to 1.45.2

--- a/rustc-1.48.0-disable-libssh2.patch
+++ b/rustc-1.48.0-disable-libssh2.patch
@ -0,0 +1,42 @@
+--- rustc-1.48.0-src/Cargo.lock.orig	2020-11-16 06:01:53.000000000 -0800
+++ rustc-1.48.0-src/Cargo.lock	2020-11-16 09:27:44.425104404 -0800
+@@ -1676,7 +1676,6 @@
+ dependencies = [
+  "cc",
+  "libc",
+- "libssh2-sys",
+  "libz-sys",
+  "openssl-sys",
+  "pkg-config",
+@@ -1693,20 +1692,6 @@
+ ]
+ 
+ [[package]]
+-name = "libssh2-sys"
+-version = "0.2.19"
+-source = "registry+https://github.com/rust-lang/crates.io-index"
+-checksum = "ca46220853ba1c512fc82826d0834d87b06bcd3c2a42241b7de72f3d2fe17056"
+-dependencies = [
+- "cc",
+- "libc",
+- "libz-sys",
+- "openssl-sys",
+- "pkg-config",
+- "vcpkg",
+-]
+-
+-[[package]]
+ name = "libz-sys"
+ version = "1.1.2"
+ source = "registry+https://github.com/rust-lang/crates.io-index"
+--- rustc-1.48.0-src/vendor/git2/Cargo.toml.orig	2020-11-16 06:27:49.000000000 -0800
+++ rustc-1.48.0-src/vendor/git2/Cargo.toml	2020-11-16 09:27:44.425104404 -0800
+@@ -49,7 +49,7 @@
+ version = "0.1.39"
+ 
+ [features]
+-default = ["ssh", "https", "ssh_key_from_memory"]
+default = ["https"]
+ https = ["libgit2-sys/https", "openssl-sys", "openssl-probe"]
+ ssh = ["libgit2-sys/ssh"]
+ ssh_key_from_memory = ["libgit2-sys/ssh_key_from_memory"]
--- a/rustc-1.51.0-backport-pr81728.patch
+++ b/rustc-1.51.0-backport-pr81728.patch
@ -0,0 +1,181 @@
+From 70f17ca715d3d7e2fd79cc909b95fd3a6357c13e Mon Sep 17 00:00:00 2001
+From: Yechan Bae <yechan@gatech.edu>
+Date: Wed, 3 Feb 2021 16:36:33 -0500
+Subject: [PATCH 1/2] Fixes #80335
+
+---
+ library/alloc/src/str.rs   | 42 ++++++++++++++++++++++----------------
+ library/alloc/tests/str.rs | 30 +++++++++++++++++++++++++++
+ 2 files changed, 54 insertions(+), 18 deletions(-)
+
+diff --git a/library/alloc/src/str.rs b/library/alloc/src/str.rs
+index 70e0c7dba5ea..a7584c6b6510 100644
+--- a/library/alloc/src/str.rs
+++ b/library/alloc/src/str.rs
+@@ -90,8 +90,8 @@ fn join(slice: &Self, sep: &str) -> String {
+     }
+ }
+ 
+-macro_rules! spezialize_for_lengths {
+-    ($separator:expr, $target:expr, $iter:expr; $($num:expr),*) => {
+macro_rules! specialize_for_lengths {
+    ($separator:expr, $target:expr, $iter:expr; $($num:expr),*) => {{
+         let mut target = $target;
+         let iter = $iter;
+         let sep_bytes = $separator;
+@@ -102,7 +102,8 @@ macro_rules! spezialize_for_lengths {
+                 $num => {
+                     for s in iter {
+                         copy_slice_and_advance!(target, sep_bytes);
+-                        copy_slice_and_advance!(target, s.borrow().as_ref());
+                        let content_bytes = s.borrow().as_ref();
+                        copy_slice_and_advance!(target, content_bytes);
+                     }
+                 },
+             )*
+@@ -110,11 +111,13 @@ macro_rules! spezialize_for_lengths {
+                 // arbitrary non-zero size fallback
+                 for s in iter {
+                     copy_slice_and_advance!(target, sep_bytes);
+-                    copy_slice_and_advance!(target, s.borrow().as_ref());
+                    let content_bytes = s.borrow().as_ref();
+                    copy_slice_and_advance!(target, content_bytes);
+                 }
+             }
+         }
+-    };
+        target
+    }}
+ }
+ 
+ macro_rules! copy_slice_and_advance {
+@@ -153,7 +156,7 @@ fn join_generic_copy<B, T, S>(slice: &[S], sep: &[T]) -> Vec<T>
+     // if the `len` calculation overflows, we'll panic
+     // we would have run out of memory anyway and the rest of the function requires
+     // the entire Vec pre-allocated for safety
+-    let len = sep_len
+    let reserved_len = sep_len
+         .checked_mul(iter.len())
+         .and_then(|n| {
+             slice.iter().map(|s| s.borrow().as_ref().len()).try_fold(n, usize::checked_add)
+@@ -161,22 +164,25 @@ fn join_generic_copy<B, T, S>(slice: &[S], sep: &[T]) -> Vec<T>
+         .expect("attempt to join into collection with len > usize::MAX");
+ 
+     // crucial for safety
+-    let mut result = Vec::with_capacity(len);
+-    assert!(result.capacity() >= len);
+    let mut result = Vec::with_capacity(reserved_len);
+    debug_assert!(result.capacity() >= reserved_len);
+ 
+     result.extend_from_slice(first.borrow().as_ref());
+ 
+     unsafe {
+-        {
+-            let pos = result.len();
+-            let target = result.get_unchecked_mut(pos..len);
+-
+-            // copy separator and slices over without bounds checks
+-            // generate loops with hardcoded offsets for small separators
+-            // massive improvements possible (~ x2)
+-            spezialize_for_lengths!(sep, target, iter; 0, 1, 2, 3, 4);
+-        }
+-        result.set_len(len);
+        let pos = result.len();
+        let target = result.get_unchecked_mut(pos..reserved_len);
+
+        // copy separator and slices over without bounds checks
+        // generate loops with hardcoded offsets for small separators
+        // massive improvements possible (~ x2)
+        let remain = specialize_for_lengths!(sep, target, iter; 0, 1, 2, 3, 4);
+
+        // issue #80335: A weird borrow implementation can return different
+        // slices for the length calculation and the actual copy, so
+        // `remain.len()` might be non-zero.
+        let result_len = reserved_len - remain.len();
+        result.set_len(result_len);
+     }
+     result
+ }
+diff --git a/library/alloc/tests/str.rs b/library/alloc/tests/str.rs
+index 604835e6cc4a..6df8d8c2f354 100644
+--- a/library/alloc/tests/str.rs
+++ b/library/alloc/tests/str.rs
+@@ -160,6 +160,36 @@ fn test_join_for_different_lengths_with_long_separator() {
+     test_join!("～～～～～a～～～～～bc", ["", "a", "bc"], "～～～～～");
+ }
+ 
+#[test]
+fn test_join_isue_80335() {
+    use core::{borrow::Borrow, cell::Cell};
+
+    struct WeirdBorrow {
+        state: Cell<bool>,
+    }
+
+    impl Default for WeirdBorrow {
+        fn default() -> Self {
+            WeirdBorrow { state: Cell::new(false) }
+        }
+    }
+
+    impl Borrow<str> for WeirdBorrow {
+        fn borrow(&self) -> &str {
+            let state = self.state.get();
+            if state {
+                "0"
+            } else {
+                self.state.set(true);
+                "123456"
+            }
+        }
+    }
+
+    let arr: [WeirdBorrow; 3] = Default::default();
+    test_join!("0-0-0", arr, "-");
+}
+
+ #[test]
+ #[cfg_attr(miri, ignore)] // Miri is too slow
+ fn test_unsafe_slice() {
+-- 
+2.31.1
+
+
+From 10020817d2e6756be1ff2ac3c182af97cf7fe904 Mon Sep 17 00:00:00 2001
+From: Yechan Bae <yechan@gatech.edu>
+Date: Sat, 20 Mar 2021 13:42:54 -0400
+Subject: [PATCH 2/2] Update the comment
+
+---
+ library/alloc/src/str.rs | 8 ++++----
+ 1 file changed, 4 insertions(+), 4 deletions(-)
+
+diff --git a/library/alloc/src/str.rs b/library/alloc/src/str.rs
+index a7584c6b6510..4d1e876457b8 100644
+--- a/library/alloc/src/str.rs
+++ b/library/alloc/src/str.rs
+@@ -163,7 +163,7 @@ fn join_generic_copy<B, T, S>(slice: &[S], sep: &[T]) -> Vec<T>
+         })
+         .expect("attempt to join into collection with len > usize::MAX");
+ 
+-    // crucial for safety
+    // prepare an uninitialized buffer
+     let mut result = Vec::with_capacity(reserved_len);
+     debug_assert!(result.capacity() >= reserved_len);
+ 
+@@ -178,9 +178,9 @@ fn join_generic_copy<B, T, S>(slice: &[S], sep: &[T]) -> Vec<T>
+         // massive improvements possible (~ x2)
+         let remain = specialize_for_lengths!(sep, target, iter; 0, 1, 2, 3, 4);
+ 
+-        // issue #80335: A weird borrow implementation can return different
+-        // slices for the length calculation and the actual copy, so
+-        // `remain.len()` might be non-zero.
+        // A weird borrow implementation may return different
+        // slices for the length calculation and the actual copy.
+        // Make sure we don't expose uninitialized bytes to the caller.
+         let result_len = reserved_len - remain.len();
+         result.set_len(result_len);
+     }
+-- 
+2.31.1
+
--- a/rustc-1.51.0-backport-pr81741.patch
+++ b/rustc-1.51.0-backport-pr81741.patch
@ -0,0 +1,44 @@
+From 40d3f2d7ef5835317fe9df9ecc01f4c363def4fd Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian@centricular.com>
+Date: Thu, 4 Feb 2021 10:23:01 +0200
+Subject: [PATCH] Increment `self.index` before calling
+ `Iterator::self.a.__iterator_get_unchecked` in `Zip` `TrustedRandomAccess`
+ specialization
+
+Otherwise if `Iterator::self.a.__iterator_get_unchecked` panics the
+index would not have been incremented yet and another call to
+`Iterator::next` would read from the same index again, which is not
+allowed according to the API contract of `TrustedRandomAccess` for
+`!Clone`.
+
+Fixes https://github.com/rust-lang/rust/issues/81740
+
+(cherry picked from commit 86a4b27475aab52b998c15f5758540697cc9cff0)
+---
+ library/core/src/iter/adapters/zip.rs | 7 ++++---
+ 1 file changed, 4 insertions(+), 3 deletions(-)
+
+diff --git a/library/core/src/iter/adapters/zip.rs b/library/core/src/iter/adapters/zip.rs
+index 98b8dca96140..9f9835345200 100644
+--- a/library/core/src/iter/adapters/zip.rs
+++ b/library/core/src/iter/adapters/zip.rs
+@@ -198,12 +198,13 @@ fn next(&mut self) -> Option<(A::Item, B::Item)> {
+                 Some((self.a.__iterator_get_unchecked(i), self.b.__iterator_get_unchecked(i)))
+             }
+         } else if A::may_have_side_effect() && self.index < self.a.size() {
+            let i = self.index;
+            self.index += 1;
+             // match the base implementation's potential side effects
+-            // SAFETY: we just checked that `self.index` < `self.a.len()`
+            // SAFETY: we just checked that `i` < `self.a.len()`
+             unsafe {
+-                self.a.__iterator_get_unchecked(self.index);
+                self.a.__iterator_get_unchecked(i);
+             }
+-            self.index += 1;
+             None
+         } else {
+             None
+-- 
+2.31.1
+
--- a/rustc-1.51.0-backport-pr81910.patch
+++ b/rustc-1.51.0-backport-pr81910.patch
@ -0,0 +1,48 @@
+From 852684d306cee955ed751f1e8d8eec6adaecff3b Mon Sep 17 00:00:00 2001
+From: Joshua Nelson <jyn514@gmail.com>
+Date: Mon, 8 Feb 2021 22:51:21 -0500
+Subject: [PATCH] Use format string in bootstrap panic instead of a string
+ directly
+
+This fixes the following warning when compiling with nightly:
+
+```
+warning: panic message is not a string literal
+    --> src/bootstrap/builder.rs:1515:24
+     |
+1515 |                 panic!(out);
+     |                        ^^^
+     |
+     = note: `#[warn(non_fmt_panic)]` on by default
+     = note: this is no longer accepted in Rust 2021
+help: add a "{}" format string to Display the message
+     |
+1515 |                 panic!("{}", out);
+     |                        ^^^^^
+help: or use std::panic::panic_any instead
+     |
+1515 |                 std::panic::panic_any(out);
+     |                 ^^^^^^^^^^^^^^^^^^^^^^
+```
+
+(cherry picked from commit 31c93397bde772764cda3058e16f9cef61895090)
+---
+ src/bootstrap/builder.rs | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
+index f1a160250dbe..0f5fcb4af400 100644
+--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
+@@ -1490,7 +1490,7 @@ pub fn ensure<S: Step>(&'a self, step: S) -> S::Output {
+                 for el in stack.iter().rev() {
+                     out += &format!("\t{:?}\n", el);
+                 }
+-                panic!(out);
+                panic!("{}", out);
+             }
+             if let Some(out) = self.cache.get(&step) {
+                 self.verbose(&format!("{}c {:?}", "  ".repeat(stack.len()), step));
+-- 
+2.31.1
+
--- a/rustc-1.51.0-backport-pr82289.patch
+++ b/rustc-1.51.0-backport-pr82289.patch
@ -0,0 +1,96 @@
+From 5222e2ba2d97cd716a379b4ae6bc62c5f7c2dd36 Mon Sep 17 00:00:00 2001
+From: Giacomo Stevanato <giaco.stevanato@gmail.com>
+Date: Fri, 19 Feb 2021 12:15:37 +0100
+Subject: [PATCH 1/3] Increment self.len in specialized ZipImpl to avoid
+ underflow in size_hint
+
+(cherry picked from commit 66a260617a88ed1ad55a46f03c5a90d5ad3004d3)
+---
+ library/core/src/iter/adapters/zip.rs | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/library/core/src/iter/adapters/zip.rs b/library/core/src/iter/adapters/zip.rs
+index 9f9835345200..f08bfac837fe 100644
+--- a/library/core/src/iter/adapters/zip.rs
+++ b/library/core/src/iter/adapters/zip.rs
+@@ -200,6 +200,7 @@ fn next(&mut self) -> Option<(A::Item, B::Item)> {
+         } else if A::may_have_side_effect() && self.index < self.a.size() {
+             let i = self.index;
+             self.index += 1;
+            self.len += 1;
+             // match the base implementation's potential side effects
+             // SAFETY: we just checked that `i` < `self.a.len()`
+             unsafe {
+-- 
+2.31.1
+
+
+From d39669fc8282830a374d19d204f7b4ee8eb1e381 Mon Sep 17 00:00:00 2001
+From: Giacomo Stevanato <giaco.stevanato@gmail.com>
+Date: Fri, 19 Feb 2021 12:16:12 +0100
+Subject: [PATCH 2/3] Add test for underflow in specialized Zip's size_hint
+
+(cherry picked from commit 8b9ac4d4155c74db5b317046033ab9c05a09e351)
+---
+ library/core/tests/iter/adapters/zip.rs | 20 ++++++++++++++++++++
+ 1 file changed, 20 insertions(+)
+
+diff --git a/library/core/tests/iter/adapters/zip.rs b/library/core/tests/iter/adapters/zip.rs
+index 1fce0951e365..a59771039295 100644
+--- a/library/core/tests/iter/adapters/zip.rs
+++ b/library/core/tests/iter/adapters/zip.rs
+@@ -245,3 +245,23 @@ fn test_double_ended_zip() {
+     assert_eq!(it.next_back(), Some((3, 3)));
+     assert_eq!(it.next(), None);
+ }
+
+#[test]
+fn test_issue_82282() {
+    fn overflowed_zip(arr: &[i32]) -> impl Iterator<Item = (i32, &())> {
+        static UNIT_EMPTY_ARR: [(); 0] = [];
+
+        let mapped = arr.into_iter().map(|i| *i);
+        let mut zipped = mapped.zip(UNIT_EMPTY_ARR.iter());
+        zipped.next();
+        zipped
+    }
+
+    let arr = [1, 2, 3];
+    let zip = overflowed_zip(&arr).zip(overflowed_zip(&arr));
+
+    assert_eq!(zip.size_hint(), (0, Some(0)));
+    for _ in zip {
+        panic!();
+    }
+}
+-- 
+2.31.1
+
+
+From 4b382167dd5ed5a6eac0cf314bfb86e3704b6e76 Mon Sep 17 00:00:00 2001
+From: Giacomo Stevanato <giaco.stevanato@gmail.com>
+Date: Fri, 19 Feb 2021 12:17:48 +0100
+Subject: [PATCH 3/3] Remove useless comparison since now self.index <=
+ self.len is an invariant
+
+(cherry picked from commit aeb4ea739efb70e0002a4a9c4c7b8027dd0620b3)
+---
+ library/core/src/iter/adapters/zip.rs | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/library/core/src/iter/adapters/zip.rs b/library/core/src/iter/adapters/zip.rs
+index f08bfac837fe..dcbcb1ce7200 100644
+--- a/library/core/src/iter/adapters/zip.rs
+++ b/library/core/src/iter/adapters/zip.rs
+@@ -261,7 +261,7 @@ fn next_back(&mut self) -> Option<(A::Item, B::Item)>
+             if sz_a != sz_b {
+                 let sz_a = self.a.size();
+                 if a_side_effect && sz_a > self.len {
+-                    for _ in 0..sz_a - cmp::max(self.len, self.index) {
+                    for _ in 0..sz_a - self.len {
+                         self.a.next_back();
+                     }
+                 }
+-- 
+2.31.1
+
--- a/rustc-1.51.0-backport-pr82292.patch
+++ b/rustc-1.51.0-backport-pr82292.patch
@ -0,0 +1,120 @@
+From 0babb88efc4d36f3defafc3c3c0343793fa05d52 Mon Sep 17 00:00:00 2001
+From: Giacomo Stevanato <giaco.stevanato@gmail.com>
+Date: Wed, 3 Mar 2021 21:09:01 +0100
+Subject: [PATCH 1/2] Prevent Zip specialization from calling
+ __iterator_get_unchecked twice with the same index after calling next_back
+
+(cherry picked from commit 2371914a05f8f2763dffe6e2511d0870bcd6b461)
+---
+ library/core/src/iter/adapters/zip.rs | 13 +++++++++----
+ 1 file changed, 9 insertions(+), 4 deletions(-)
+
+diff --git a/library/core/src/iter/adapters/zip.rs b/library/core/src/iter/adapters/zip.rs
+index dcbcb1ce7200..7dac0c63ca2d 100644
+--- a/library/core/src/iter/adapters/zip.rs
+++ b/library/core/src/iter/adapters/zip.rs
+@@ -13,9 +13,10 @@
+ pub struct Zip<A, B> {
+     a: A,
+     b: B,
+-    // index and len are only used by the specialized version of zip
+    // index, len and a_len are only used by the specialized version of zip
+     index: usize,
+     len: usize,
+    a_len: usize,
+ }
+ impl<A: Iterator, B: Iterator> Zip<A, B> {
+     pub(in crate::iter) fn new(a: A, b: B) -> Zip<A, B> {
+@@ -110,6 +111,7 @@ impl<A, B> ZipImpl<A, B> for Zip<A, B>
+             b,
+             index: 0, // unused
+             len: 0,   // unused
+            a_len: 0, // unused
+         }
+     }
+ 
+@@ -184,8 +186,9 @@ impl<A, B> ZipImpl<A, B> for Zip<A, B>
+     B: TrustedRandomAccess + Iterator,
+ {
+     fn new(a: A, b: B) -> Self {
+-        let len = cmp::min(a.size(), b.size());
+-        Zip { a, b, index: 0, len }
+        let a_len = a.size();
+        let len = cmp::min(a_len, b.size());
+        Zip { a, b, index: 0, len, a_len }
+     }
+ 
+     #[inline]
+@@ -197,7 +200,7 @@ fn next(&mut self) -> Option<(A::Item, B::Item)> {
+             unsafe {
+                 Some((self.a.__iterator_get_unchecked(i), self.b.__iterator_get_unchecked(i)))
+             }
+-        } else if A::may_have_side_effect() && self.index < self.a.size() {
+        } else if A::may_have_side_effect() && self.index < self.a_len {
+             let i = self.index;
+             self.index += 1;
+             self.len += 1;
+@@ -264,6 +267,7 @@ fn next_back(&mut self) -> Option<(A::Item, B::Item)>
+                     for _ in 0..sz_a - self.len {
+                         self.a.next_back();
+                     }
+                    self.a_len = self.len;
+                 }
+                 let sz_b = self.b.size();
+                 if b_side_effect && sz_b > self.len {
+@@ -275,6 +279,7 @@ fn next_back(&mut self) -> Option<(A::Item, B::Item)>
+         }
+         if self.index < self.len {
+             self.len -= 1;
+            self.a_len -= 1;
+             let i = self.len;
+             // SAFETY: `i` is smaller than the previous value of `self.len`,
+             // which is also smaller than or equal to `self.a.len()` and `self.b.len()`
+-- 
+2.31.1
+
+
+From 19af66a6f3e2bbb4780bb9eae7eb53bd13e3dd0f Mon Sep 17 00:00:00 2001
+From: Giacomo Stevanato <giaco.stevanato@gmail.com>
+Date: Fri, 19 Feb 2021 15:25:09 +0100
+Subject: [PATCH 2/2] Add relevant test
+
+(cherry picked from commit c1bfb9a78db6d481be1d03355672712c766e20b0)
+---
+ library/core/tests/iter/adapters/zip.rs | 23 +++++++++++++++++++++++
+ 1 file changed, 23 insertions(+)
+
+diff --git a/library/core/tests/iter/adapters/zip.rs b/library/core/tests/iter/adapters/zip.rs
+index a59771039295..000c15f72c88 100644
+--- a/library/core/tests/iter/adapters/zip.rs
+++ b/library/core/tests/iter/adapters/zip.rs
+@@ -265,3 +265,26 @@ fn overflowed_zip(arr: &[i32]) -> impl Iterator<Item = (i32, &())> {
+         panic!();
+     }
+ }
+
+#[test]
+fn test_issue_82291() {
+    use std::cell::Cell;
+
+    let mut v1 = [()];
+    let v2 = [()];
+
+    let called = Cell::new(0);
+
+    let mut zip = v1
+        .iter_mut()
+        .map(|r| {
+            called.set(called.get() + 1);
+            r
+        })
+        .zip(&v2);
+
+    zip.next_back();
+    assert_eq!(called.get(), 1);
+    zip.next();
+    assert_eq!(called.get(), 1);
+}
+-- 
+2.31.1
+
--- a/rustc-1.51.0-backport-pr83629.patch
+++ b/rustc-1.51.0-backport-pr83629.patch
@ -0,0 +1,142 @@
+From 3834e7b7393bf1a0d7df02ccd1d2e896c1465769 Mon Sep 17 00:00:00 2001
+From: The8472 <git@infinite-source.de>
+Date: Mon, 29 Mar 2021 04:22:34 +0200
+Subject: [PATCH 1/2] add testcase for double-drop during Vec in-place
+ collection
+
+---
+ library/alloc/tests/vec.rs | 38 +++++++++++++++++++++++++++++++++++++-
+ 1 file changed, 37 insertions(+), 1 deletion(-)
+
+diff --git a/library/alloc/tests/vec.rs b/library/alloc/tests/vec.rs
+index 5c7ff67bc621..4cdb7eefcdf1 100644
+--- a/library/alloc/tests/vec.rs
+++ b/library/alloc/tests/vec.rs
+@@ -954,7 +954,7 @@ fn test_from_iter_specialization_head_tail_drop() {
+ }
+ 
+ #[test]
+-fn test_from_iter_specialization_panic_drop() {
+fn test_from_iter_specialization_panic_during_iteration_drops() {
+     let drop_count: Vec<_> = (0..=2).map(|_| Rc::new(())).collect();
+     let src: Vec<_> = drop_count.iter().cloned().collect();
+     let iter = src.into_iter();
+@@ -977,6 +977,42 @@ fn test_from_iter_specialization_panic_drop() {
+     );
+ }
+ 
+#[test]
+fn test_from_iter_specialization_panic_during_drop_leaks() {
+    static mut DROP_COUNTER: usize = 0;
+
+    #[derive(Debug)]
+    enum Droppable {
+        DroppedTwice(Box<i32>),
+        PanicOnDrop,
+    }
+
+    impl Drop for Droppable {
+        fn drop(&mut self) {
+            match self {
+                Droppable::DroppedTwice(_) => {
+                    unsafe {
+                        DROP_COUNTER += 1;
+                    }
+                    println!("Dropping!")
+                }
+                Droppable::PanicOnDrop => {
+                    if !std::thread::panicking() {
+                        panic!();
+                    }
+                }
+            }
+        }
+    }
+
+    let _ = std::panic::catch_unwind(AssertUnwindSafe(|| {
+        let v = vec![Droppable::DroppedTwice(Box::new(123)), Droppable::PanicOnDrop];
+        let _ = v.into_iter().take(0).collect::<Vec<_>>();
+    }));
+
+    assert_eq!(unsafe { DROP_COUNTER }, 1);
+}
+
+ #[test]
+ fn test_cow_from() {
+     let borrowed: &[_] = &["borrowed", "(slice)"];
+-- 
+2.31.1
+
+
+From 8e2706343e1ce1c5a2d3a2ceaaaa010aaeb21d93 Mon Sep 17 00:00:00 2001
+From: The8472 <git@infinite-source.de>
+Date: Mon, 29 Mar 2021 04:22:48 +0200
+Subject: [PATCH 2/2] fix double-drop in in-place collect specialization
+
+---
+ library/alloc/src/vec/into_iter.rs          | 27 ++++++++++++++-------
+ library/alloc/src/vec/source_iter_marker.rs |  4 +--
+ 2 files changed, 20 insertions(+), 11 deletions(-)
+
+diff --git a/library/alloc/src/vec/into_iter.rs b/library/alloc/src/vec/into_iter.rs
+index f131d06bb18f..74adced53f6d 100644
+--- a/library/alloc/src/vec/into_iter.rs
+++ b/library/alloc/src/vec/into_iter.rs
+@@ -85,20 +85,29 @@ fn as_raw_mut_slice(&mut self) -> *mut [T] {
+         ptr::slice_from_raw_parts_mut(self.ptr as *mut T, self.len())
+     }
+ 
+-    pub(super) fn drop_remaining(&mut self) {
+-        unsafe {
+-            ptr::drop_in_place(self.as_mut_slice());
+-        }
+-        self.ptr = self.end;
+-    }
+    /// Drops remaining elements and relinquishes the backing allocation.
+    ///
+    /// This is roughly equivalent to the following, but more efficient
+    ///
+    /// ```
+    /// # let mut into_iter = Vec::<u8>::with_capacity(10).into_iter();
+    /// (&mut into_iter).for_each(core::mem::drop);
+    /// unsafe { core::ptr::write(&mut into_iter, Vec::new().into_iter()); }
+    /// ```
+    pub(super) fn forget_allocation_drop_remaining(&mut self) {
+        let remaining = self.as_raw_mut_slice();
+ 
+-    /// Relinquishes the backing allocation, equivalent to
+-    /// `ptr::write(&mut self, Vec::new().into_iter())`
+-    pub(super) fn forget_allocation(&mut self) {
+        // overwrite the individual fields instead of creating a new
+        // struct and then overwriting &mut self.
+        // this creates less assembly
+         self.cap = 0;
+         self.buf = unsafe { NonNull::new_unchecked(RawVec::NEW.ptr()) };
+         self.ptr = self.buf.as_ptr();
+         self.end = self.buf.as_ptr();
+
+        unsafe {
+            ptr::drop_in_place(remaining);
+        }
+     }
+ }
+ 
+diff --git a/library/alloc/src/vec/source_iter_marker.rs b/library/alloc/src/vec/source_iter_marker.rs
+index 8c0e95559fa1..9301f7a5184e 100644
+--- a/library/alloc/src/vec/source_iter_marker.rs
+++ b/library/alloc/src/vec/source_iter_marker.rs
+@@ -78,9 +78,9 @@ impl<T, I> SpecFromIter<T, I> for Vec<T>
+         }
+ 
+         // drop any remaining values at the tail of the source
+-        src.drop_remaining();
+         // but prevent drop of the allocation itself once IntoIter goes out of scope
+-        src.forget_allocation();
+        // if the drop panics then we also leak any elements collected into dst_buf
+        src.forget_allocation_drop_remaining();
+ 
+         let vec = unsafe {
+             let len = dst.offset_from(dst_buf) as usize;
+-- 
+2.31.1
+
--- a/rustc-1.51.0-disable-http2.patch
+++ b/rustc-1.51.0-disable-http2.patch
@ -0,0 +1,66 @@
+--- rustc-beta-src/Cargo.lock.orig	2021-03-09 10:30:08.626424998 -0800
+++ rustc-beta-src/Cargo.lock	2021-03-09 10:32:38.096207704 -0800
+@@ -899,7 +899,6 @@
+ dependencies = [
+  "cc",
+  "libc",
+- "libnghttp2-sys",
+  "libz-sys",
+  "openssl-sys",
+  "pkg-config",
+@@ -1860,16 +1859,6 @@
+ ]
+ 
+ [[package]]
+-name = "libnghttp2-sys"
+-version = "0.1.4+1.41.0"
+-source = "registry+https://github.com/rust-lang/crates.io-index"
+-checksum = "03624ec6df166e79e139a2310ca213283d6b3c30810c54844f307086d4488df1"
+-dependencies = [
+- "cc",
+- "libc",
+-]
+-
+-[[package]]
+ name = "libz-sys"
+ version = "1.1.2"
+ source = "registry+https://github.com/rust-lang/crates.io-index"
+--- rustc-beta-src/src/tools/cargo/Cargo.toml.orig	2021-03-05 08:34:15.000000000 -0800
+++ rustc-beta-src/src/tools/cargo/Cargo.toml	2021-03-09 10:32:38.096207704 -0800
+@@ -25,7 +25,7 @@
+ crates-io = { path = "crates/crates-io", version = "0.33.0" }
+ crossbeam-utils = "0.8"
+ crypto-hash = "0.3.1"
+-curl = { version = "0.4.23", features = ["http2"] }
+curl = { version = "0.4.23", features = [] }
+ curl-sys = "0.4.22"
+ env_logger = "0.8.1"
+ pretty_env_logger = { version = "0.4", optional = true }
+--- rustc-beta-src/src/tools/cargo/src/cargo/core/package.rs.orig	2021-03-05 08:34:15.000000000 -0800
+++ rustc-beta-src/src/tools/cargo/src/cargo/core/package.rs	2021-03-09 10:32:38.096207704 -0800
+@@ -412,14 +412,8 @@
+         // Also note that pipelining is disabled as curl authors have indicated
+         // that it's buggy, and we've empirically seen that it's buggy with HTTP
+         // proxies.
+-        let mut multi = Multi::new();
+-        let multiplexing = config.http_config()?.multiplexing.unwrap_or(true);
+-        multi
+-            .pipelining(false, multiplexing)
+-            .chain_err(|| "failed to enable multiplexing/pipelining in curl")?;
+-
+-        // let's not flood crates.io with connections
+-        multi.set_max_host_connections(2)?;
+        let multi = Multi::new();
+        let multiplexing = false;
+ 
+         Ok(PackageSet {
+             packages: package_ids
+@@ -592,7 +586,7 @@
+ macro_rules! try_old_curl {
+     ($e:expr, $msg:expr) => {
+         let result = $e;
+-        if cfg!(target_os = "macos") {
+        if cfg!(any(target_os = "linux", target_os = "macos")) {
+             if let Err(e) = result {
+                 warn!("ignoring libcurl {} error: {}", $msg, e);
+             }
--- a/rustc-1.51.0-src.tar.xz
+++ b/rustc-1.51.0-src.tar.xz
--- a/rustc-1.51.0-src.tar.xz.aa
+++ b/rustc-1.51.0-src.tar.xz.aa
--- a/rustc-1.51.0-src.tar.xz.ab
+++ b/rustc-1.51.0-src.tar.xz.ab