Use macOSVersion in isSwiftCompatible

src/languages/swift.test.ts

@@ -3,6 +3,7 @@ import sinon from "sinon";
 
 import { ActionsEnvVars } from "../environment";
 import {
+  checkExpectedLogMessages,
   createTestConfig,
   getCodeQLForTesting,
   getTestEnv,
@@ -68,3 +69,14 @@ for (const nonDarwinPlatform of nonDarwinPlatforms) {
     );
   });
 }
+
+test("checkSwiftCompatibility warns if version string is not a semver", (t) => {
+  const logger = new RecordingLogger();
+  checkSwiftCompatibility(
+    initAllState({ logger, platform: "darwin", osRelease: "unexpected" }),
+    createTestConfig({ languages: [BuiltInLanguage.swift] }),
+  );
+  checkExpectedLogMessages(t, logger.messages, [
+    "Unable to determine version of macOS, got: unexpected",
+  ]);
+});

src/languages/swift.ts

@@ -1,5 +1,6 @@
 import { ActionState } from "../action-common";
 import { Config } from "../config-utils";
+import { macOSVersion } from "../platform";
 import { ConfigurationError } from "../util";
 
 import { BuiltInLanguage } from ".";
@@ -13,15 +14,28 @@ import { BuiltInLanguage } from ".";
  * @throws {ConfigurationError} If Swift analysis is not possible on the current runner.
  */
 export function checkSwiftCompatibility(
-  action: ActionState<["Base"]>,
+  action: ActionState<["Base", "Logger"]>,
   config: Config,
 ) {
-  if (
-    config.languages.includes(BuiltInLanguage.swift) &&
-    action.platform !== "darwin"
-  ) {
+  // The checks are not relevant if we are not trying to analyse Swift.
+  if (!config.languages.includes(BuiltInLanguage.swift)) {
+    return;
+  }
+
+  // Try to get the macOS version.
+  const version = macOSVersion(action);
+
+  // If `version` is undefined, then we are not on macOS.
+  if (version === undefined) {
     throw new ConfigurationError(
       `Swift analysis is only supported on macOS runner images. Please migrate to a macOS runner.`,
     );
   }
+  // If we got a string, we are on macOS but couldn't parse the version string.
+  if (typeof version === "string") {
+    action.logger.warning(
+      `Unable to determine version of macOS, got: ${version}`,
+    );
+    return;
+  }
 }