Auto merge of #75908 - pietroalbini:ci-bump-llvm, r=Mark-Simulacrum

Bump LLVM on CI to 10.0.0

This PR bumps the LLVM version we use on our macOS and Windows CI to 10.0.0, fixing a breakage we noticed today:

```
2020-08-25T14:24:28.5939568Z FAILED: lib/Support/CMakeFiles/LLVMSupport.dir/AMDGPUMetadata.cpp.obj
2020-08-25T14:24:28.5940317Z D:\a\rust\rust\build\bootstrap\debug\sccache-plus-cl.exe  /nologo -TP -DGTEST_HAS_RTTI=0 -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_HAS_EXCEPTIONS=0 -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Ilib\Support -ID:\a\rust\rust\src\llvm-project\llvm\lib\Support -Iinclude -ID:\a\rust\rust\src\llvm-project\llvm\include -nologo -MT -Brepro --target=x86_64-pc-windows-msvc /Zc:inline /Zc:strictStrings /Oi /Zc:rvalueCast /Brepro /W4  -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wno-noexcept-type -Wno-comment /Gw /MT /O2 /Ob2 -UNDEBUG -std:c++14  /EHs-c- /GR- /showIncludes /Folib\Support\CMakeFiles\LLVMSupport.dir\AMDGPUMetadata.cpp.obj /Fdlib\Support\CMakeFiles\LLVMSupport.dir\LLVMSupport.pdb -c D:\a\rust\rust\src\llvm-project\llvm\lib\Support\AMDGPUMetadata.cpp
2020-08-25T14:24:28.5940861Z clang-cl: warning: argument unused during compilation: '-Brepro' [-Wunused-command-line-argument]
2020-08-25T14:24:28.5941076Z clang-cl: warning: argument unused during compilation: '-Brepro' [-Wunused-command-line-argument]
2020-08-25T14:24:28.5941321Z In file included from D:\a\rust\rust\src\llvm-project\llvm\lib\Support\AMDGPUMetadata.cpp:15:
2020-08-25T14:24:28.5941545Z In file included from D:\a\rust\rust\src\llvm-project\llvm\include\llvm/ADT/Twine.h:12:
2020-08-25T14:24:28.5941774Z In file included from D:\a\rust\rust\src\llvm-project\llvm\include\llvm/ADT/SmallVector.h:16:
2020-08-25T14:24:28.5942016Z In file included from D:\a\rust\rust\src\llvm-project\llvm\include\llvm/ADT/iterator_range.h:21:
2020-08-25T14:24:28.5942257Z In file included from C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Tools\MSVC\14.27.29110\include\iterator:9:
2020-08-25T14:24:28.5942542Z C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Tools\MSVC\14.27.29110\include\yvals_core.h(494,2): error: STL1000: Unexpected compiler version, expected Clang 10.0.0 or newer.
```

I uploaded both the new tarballs to our mirrors bucket.

src/ci/docker/host-x86_64/dist-x86_64-linux/build-clang.sh

@@ -4,7 +4,7 @@ set -ex
 
 source shared.sh
 
-LLVM=llvmorg-9.0.0
+LLVM=llvmorg-10.0.0
 
 mkdir llvm-project
 cd llvm-project

src/ci/scripts/install-clang.sh

@@ -8,11 +8,14 @@ IFS=$'\n\t'
 
 source "$(cd "$(dirname "$0")" && pwd)/../shared.sh"
 
+# Update both macOS's and Windows's tarballs when bumping the version here.
+LLVM_VERSION="10.0.0"
+
 if isMacOS; then
-    curl -f "${MIRRORS_BASE}/clang%2Bllvm-9.0.0-x86_64-darwin-apple.tar.xz" | tar xJf -
+    curl -f "${MIRRORS_BASE}/clang%2Bllvm-${LLVM_VERSION}-x86_64-apple-darwin.tar.xz" | tar xJf -
 
-    ciCommandSetEnv CC "$(pwd)/clang+llvm-9.0.0-x86_64-darwin-apple/bin/clang"
-    ciCommandSetEnv CXX "$(pwd)/clang+llvm-9.0.0-x86_64-darwin-apple/bin/clang++"
+    ciCommandSetEnv CC "$(pwd)/clang+llvm-${LLVM_VERSION}-x86_64-apple-darwin/bin/clang"
+    ciCommandSetEnv CXX "$(pwd)/clang+llvm-${LLVM_VERSION}-x86_64-apple-darwin/bin/clang++"
 
     # macOS 10.15 onwards doesn't have libraries in /usr/include anymore: those
     # are now located deep into the filesystem, under Xcode's own files. The
@@ -33,8 +36,10 @@ elif isWindows && [[ ${CUSTOM_MINGW-0} -ne 1 ]]; then
     #
     # Note that the LLVM installer is an NSIS installer
     #
-    # Original downloaded here came from
-    # http://releases.llvm.org/9.0.0/LLVM-9.0.0-win64.exe
+    # Original downloaded here came from:
+    #
+    #   https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/LLVM-10.0.0-win64.exe
+    #
     # That installer was run through `wine ./installer.exe /S /NCRC` on Linux
     # and then the resulting installation directory (found in
     # `$HOME/.wine/drive_c/Program Files/LLVM`) was packaged up into a tarball.
@@ -45,7 +50,7 @@ elif isWindows && [[ ${CUSTOM_MINGW-0} -ne 1 ]]; then
 
     mkdir -p citools
     cd citools
-    curl -f "${MIRRORS_BASE}/LLVM-9.0.0-win64.tar.gz" | tar xzf -
+    curl -f "${MIRRORS_BASE}/LLVM-${LLVM_VERSION}-win64.tar.gz" | tar xzf -
     ciCommandSetEnv RUST_CONFIGURE_ARGS \
         "${RUST_CONFIGURE_ARGS} --set llvm.clang-cl=$(pwd)/clang-rust/bin/clang-cl.exe"
 fi