Add lint to ensure that compatibility tests are implemented for new v…

…ersions of StableHLO (#1670)

This will fail if we bump the version to `Version(0, 15, 0)` without
adding new compatibility tests.

Fixes #1563

.github/workflows/lint.yml

@@ -50,3 +50,15 @@ jobs:
       - name: Run Whitespace Checks
         run: |
           ./build_tools/github_actions/lint_whitespace_checks.sh
+
+  version-checks:
+    # This job can only be run on pull_request since GITHUB_BASE_REF is only set on PR.
+    if: "github.event_name == 'pull_request'"
+    runs-on: ${{ github.repository == 'openxla/stablehlo' && 'ubuntu-22.04-64core' ||  'ubuntu-22.04'  }}
+    steps:
+      - name: Checking out repository
+        uses: actions/checkout@v2
+
+      - name: Run Version Checks
+        run: |
+          ./build_tools/github_actions/lint_version.sh

build_tools/github_actions/lint_version.sh

@@ -0,0 +1,58 @@
+# Copyright 2023 The StableHLO Authors.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This lint validates that there are compatibility tests for the current
+# version by extracting the current version vX.Y.Z from Version.h and
+# checking if files named stablehlo_legalize_to_vhlo.X_Y_0.mlir and .mlir.bc
+# exist.
+
+## Setup VERSION variable as global:
+VERSION_H="stablehlo/dialect/Version.h"
+set_version_var() {
+  # getCurrentVersion() { Version(0, X, Y); }
+  VERSION_STR=$(cat $VERSION_H | grep getCurrentVersion -A1 | grep -o 'Version([0-9], .*)')
+  REGEX="Version\(([0-9]+), ([0-9]+), ([0-9]+)\)"
+  if [[ $VERSION_STR =~ $REGEX ]]; then
+    VERSION=(${BASH_REMATCH[1]} ${BASH_REMATCH[2]} ${BASH_REMATCH[3]})
+  else
+    echo "Error: Could not find current version string in $VERSION_H" >&2
+    exit 1
+  fi
+}
+set_version_var
+
+## Check if compatibility tests exist for version `X_Y_0`
+COMPAT_TEST_BASE="stablehlo/tests/stablehlo_legalize_to_vhlo"
+COMPAT_TEST="$COMPAT_TEST_BASE.mlir"
+TEST_VERSION="${VERSION[0]}_${VERSION[1]}_0"
+VERSIONED_COMPAT_TEST="$COMPAT_TEST_BASE.$TEST_VERSION.mlir"
+VERSIONED_COMPAT_TEST_BC="$COMPAT_TEST_BASE.$TEST_VERSION.mlir.bc"
+
+show_help() {
+  HELP_URL="https://github.com/openxla/stablehlo/blob/main/docs/vhlo.md#add-versioned-serialization-test"
+  echo "For details on creating versioned tests for a new minor version of"
+  echo "StableHLO, see the instructions on:"
+  echo "$HELP_URL"
+}
+
+if ! test -e "$VERSIONED_COMPAT_TEST"; then
+  echo "Error: Could not find compatibility test $VERSIONED_COMPAT_TEST"
+  show_help
+  exit 1
+fi
+
+if ! test -e "$VERSIONED_COMPAT_TEST_BC"; then
+  echo "Error: Could not find compatibility bytecode test $VERSIONED_COMPAT_TEST_BC"
+  show_help
+  exit 1
+fi