ci: add breaking change detector

.github/workflows/breaking_changes_detector.yml

@@ -0,0 +1,143 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+
+# Detect semver-incompatible (breaking) API changes in crates modified by a PR.
+#
+# Only public workspace crates that have file changes are checked.
+# Internal crates (benchmarks, test-utils, sqllogictest, doc) are excluded.
+#
+# If breaking changes are found, a sticky comment is posted on the PR.
+# The comment is removed automatically once the issues are resolved.
+
+name: "Detect breaking changes"
+
+on:
+  pull_request:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+jobs:
+  check-semver:
+    name: Check semver
+    runs-on: ubuntu-latest
+    outputs:
+      logs: ${{ steps.check_semver.outputs.logs }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      # For fork PRs, `origin` points to the fork, not the upstream repo.
+      # Explicitly fetch the base branch from the upstream repo so we have
+      # a valid baseline ref for both diff and semver-checks.
+      - name: Fetch base branch
+        run: git fetch https://github.com/${{ github.repository }}.git ${{ github.base_ref }}:refs/remotes/origin/${{ github.base_ref }}
+
+      - name: Determine changed crates
+        id: changed_crates
+        run: |
+          # Parse workspace members from root Cargo.toml, excluding internal crates
+          # that are not published / not part of the public API.
+          MEMBERS=$(sed -n '/^members = \[/,/\]/p' Cargo.toml | grep '"' | sed 's/.*"\(.*\)".*/\1/' \
+            | grep -v -e '^benchmarks$' -e '^test-utils$' -e '^datafusion/sqllogictest$' -e '^datafusion/doc$')
+
+          # Diff against the base branch to find which files changed in this PR
+          CHANGED_FILES=$(git diff --name-only origin/${{ github.base_ref }}...HEAD)
+
+          # For each workspace member, check if any of its files were modified.
+          # If so, extract the crate name from its Cargo.toml.
+          PACKAGES=""
+          for member in $MEMBERS; do
+            if echo "$CHANGED_FILES" | grep -q "^${member}/"; then
+              pkg=$(grep '^name\s*=' "$member/Cargo.toml" | head -1 | sed 's/.*=\s*"\(.*\)"/\1/')
+              if [ -n "$pkg" ]; then
+                PACKAGES="$PACKAGES $pkg"
+              fi
+            fi
+          done
+
+          PACKAGES=$(echo "$PACKAGES" | xargs)
+          echo "packages=$PACKAGES" >> "$GITHUB_OUTPUT"
+          echo "Changed crates: $PACKAGES"
+
+      # Only install toolchain and cargo-semver-checks if there are crates to check
+      - name: Install Rust toolchain
+        if: steps.changed_crates.outputs.packages != ''
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Install cargo-semver-checks
+        if: steps.changed_crates.outputs.packages != ''
+        run: cargo install cargo-semver-checks
+
+      - name: Run cargo-semver-checks
+        id: check_semver
+        if: steps.changed_crates.outputs.packages != ''
+        run: |
+          set +e
+          ARGS=""
+          for pkg in ${{ steps.changed_crates.outputs.packages }}; do
+            ARGS="$ARGS --package $pkg"
+          done
+
+          # Compare the PR's code against the base branch to detect breaking changes.
+          # Use tee to show output in the Actions log while also capturing it.
+          # Strip ANSI escape codes from the captured output for the PR comment.
+          cargo semver-checks --baseline-rev origin/${{ github.base_ref }} $ARGS 2>&1 | tee /tmp/semver-output.txt
+          EXIT_CODE=${PIPESTATUS[0]}
+          OUTPUT=$(sed 's/\x1b\[[0-9;]*m//g' /tmp/semver-output.txt)
+          echo "logs<<EOF" >> "$GITHUB_OUTPUT"
+          echo "$OUTPUT" >> "$GITHUB_OUTPUT"
+          echo "EOF" >> "$GITHUB_OUTPUT"
+          exit $EXIT_CODE
+
+  # Post or remove a sticky comment on the PR based on the semver check result.
+  comment-on-pr:
+    name: Comment on pull request
+    runs-on: ubuntu-latest
+    needs: check-semver
+    if: always()
+    permissions:
+      contents: read
+      pull-requests: write
+    steps:
+      - name: Comment
+        if: ${{ needs.check-semver.result != 'success' }}
+        uses: marocchino/sticky-pull-request-comment@v2
+        with:
+          header: pr-semver-check-error
+          message: |
+            Thank you for opening this pull request!
+
+            Reviewer note: [cargo-semver-checks](https://github.com/obi1kenobi/cargo-semver-checks) reported the current version number is not SemVer-compatible with the changes made since the last release.
+
+            Details:
+
+            ```
+            ${{ needs.check-semver.outputs.logs }}
+            ```
+
+      # Remove the comment if the check passes (e.g. after the PR is updated)
+      - name: Delete comment
+        if: ${{ needs.check-semver.result == 'success' }}
+        uses: marocchino/sticky-pull-request-comment@v2
+        with:
+          header: pr-semver-check-error
+          delete: true