chore: add breaking changes script

Author: grdsdev

scripts/check-for-breaking-api-changes.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+##===----------------------------------------------------------------------===##
+##
+## This source file is part of the SwiftOpenAPIGenerator open source project
+##
+## Copyright (c) 2023 Apple Inc. and the SwiftOpenAPIGenerator project authors
+## Licensed under Apache License v2.0
+##
+## See LICENSE.txt for license information
+## See CONTRIBUTORS.txt for the list of SwiftOpenAPIGenerator project authors
+##
+## SPDX-License-Identifier: Apache-2.0
+##
+##===----------------------------------------------------------------------===##
+
+set -euo pipefail
+
+log() { printf -- "** %s\n" "$*" >&2; }
+error() { printf -- "** ERROR: %s\n" "$*" >&2; }
+fatal() { error "$@"; exit 1; }
+
+CURRENT_SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+REPO_ROOT="$(git -C "${CURRENT_SCRIPT_DIR}" rev-parse --show-toplevel)"
+
+log "Checking required environment variables..."
+test -n "${BASELINE_REPO_URL:-}" || fatal "BASELINE_REPO_URL unset"
+test -n "${BASELINE_TREEISH:-}" || fatal "BASELINE_TREEISH unset"
+
+log "Fetching baseline: ${BASELINE_REPO_URL}#${BASELINE_TREEISH}..."
+git -C "${REPO_ROOT}" fetch "${BASELINE_REPO_URL}" "${BASELINE_TREEISH}"
+BASELINE_COMMIT=$(git -C "${REPO_ROOT}" rev-parse FETCH_HEAD)
+
+log "Checking for API changes since ${BASELINE_REPO_URL}#${BASELINE_TREEISH} (${BASELINE_COMMIT})..."
+swift package --package-path "${REPO_ROOT}" diagnose-api-breaking-changes \
+  "${BASELINE_COMMIT}" \
+  && RC=$? || RC=$?
+
+if [ "${RC}" -ne 0 ]; then
+  fatal "❌ Breaking API changes detected."
+  exit "${RC}"
+fi
+log "✅ No breaking API changes detected."