CI: install clang-tidy (#23518)

Summary: Install clang-tidy (from LLVM 8) for the `clang_tidy` job. Pull Request resolved: https://github.com/pytorch/pytorch/pull/23518 Differential Revision: D16549621 Pulled By: ezyang fbshipit-source-id: b1d20641380cdfdb0589249770b98163528fa69f

CI: install clang-tidy (#23518)
Summary: Install clang-tidy (from LLVM 8) for the `clang_tidy` job. Pull Request resolved: https://github.com/pytorch/pytorch/pull/23518 Differential Revision: D16549621 Pulled By: ezyang fbshipit-source-id: b1d20641380cdfdb0589249770b98163528fa69f
3a568c9a · Edward Thomson · Facebook Github Bot · a8edc2b5 · 3a568c9a
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -85,6 +85,12 @@ jobs:
  - task: UsePythonVersion@0
    inputs:
      versionSpec: "3.6"
+  - script: |
+      wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
+      sudo apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-8 main"
+      sudo apt-get update
+      sudo apt-get install -y clang-tidy-8
+      sudo update-alternatives --install /usr/bin/clang-tidy clang-tidy /usr/bin/clang-tidy-8 1000
  - script: git branch master origin/master
  - script: pip install pyyaml
  - script: tools/run-clang-tidy-in-ci.sh