Add CI workflow to check c10 is synced with PyTorch

This script checks that all files in our c10 copy are in sync with our pinned version of PyTorch.

Test Plan: 1) detected us being out of sync when I wrote this PR
2) CI to run it and make sure that we are clean now

ghstack-source-id: 8eb6700
ghstack-comment-id: 2825552562
Pull-Request-resolved: #10413

Author: swolchok

.ci/scripts/check_c10_sync.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+set -eux
+ls pytorch/.git || git clone https://github.com/pytorch/pytorch.git
+pytorch_pin="$(< .ci/docker/ci_commit_pins/pytorch.txt)"
+pushd pytorch
+git checkout "$pytorch_pin"
+popd
+"$(dirname "${BASH_SOURCE[0]}")"/compare_dirs.sh runtime/core/portable_type/c10/c10 pytorch/c10

.ci/scripts/compare_dirs.sh

@@ -0,0 +1,54 @@
+#!/bin/bash
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+set -eux
+
+# Check if dir1's files are also found in dir2 with the same
+# contents. Exempt files named BUCK, CMakeLists.txt, TARGETS, or
+# targets.bzl.
+
+if [ $# -ne 2 ]; then
+    echo "Usage: $0 dir1 dir2" >&2
+    exit 1
+fi
+dir1="$1"
+dir2="$2"
+
+if [ ! -d "$dir1" ] || [ ! -d "$dir2" ]; then
+    echo "Error: Both directories must exist" >&2
+    exit 1
+fi
+
+exit_status=0
+while IFS= read -r -d '' file; do
+    base=$(basename "$file")
+    case "$base" in
+        "BUCK"|"CMakeLists.txt"|"TARGETS"|"targets.bzl")
+            continue
+            ;;
+    esac
+    # Construct the corresponding path in the second directory
+    file2="$dir2/${file#$dir1/}"
+    # Check if the corresponding file exists in the second directory
+    if [ ! -f "$file2" ]; then
+        echo "Error: File '$file' found in '$dir1' but not found in '$dir2'" >&2
+        exit 1
+    fi
+    # Compare the contents of the two files using diff
+    set +ex
+    differences=$(diff -u -p "$file" "$file2")
+    set -e # leave x off
+    # If there are any differences, print an error message and exit with failure status
+    if [ -n "$differences" ]; then
+        echo "Error: Mismatch detected in file '$file':" >&2
+        echo "$differences" >&2
+        exit_status=1
+    fi
+    set -x
+done < <(find "$dir1" -type f -print0)
+
+exit $exit_status

.github/workflows/check-c10-sync.yml

@@ -0,0 +1,27 @@
+name: check-c10-sync
+
+on:
+  pull_request:
+    paths:
+      - .ci/docker/ci_commit_pins/pytorch.txt
+      - .ci/scripts/compare_dirs.sh
+      - runtime/core/portable_type/c10/**
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}-${{ github.event_name == 'workflow_dispatch' }}-${{ github.event_name == 'schedule' }}
+  cancel-in-progress: true
+
+jobs:
+  check-c10-sync:
+    permissions:
+      id-token: write
+      contents: read
+    name: check-c10-sync
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+      - name: Clone PyTorch
+        run: |
+          .ci/scripts/check_c10_sync.sh