Support determining Dotcom CLI version from feature flags

src/util.ts

@@ -19,6 +19,7 @@ import {
   parsePacksSpecification,
   prettyPrintPack,
 } from "./config-utils";
+import * as defaults from "./defaults.json"; // Referenced from codeql-action-sync-tool!
 import { Feature, FeatureEnablement } from "./feature-flags";
 import { KOTLIN_SWIFT_BYPASS, Language } from "./languages";
 import { Logger } from "./logging";
@@ -901,3 +902,44 @@ export function parseMatrixInput(
   }
   return JSON.parse(matrixInput);
 }
+
+/** Version information about a CodeQL bundle. */
+export interface CodeqlBundleVersionInfo {
+  /** Version number of the CLI contained within this bundle. */
+  cliVersion: string;
+  /** The name of the tag of the GitHub Release containing this bundle. */
+  tagName: string;
+  /**
+   * Version number of this bundle within the toolcache.
+   *
+   * For compatibility with previous runner images and toolcaches, consumers should fallback to
+   * looking up the `0.0.0-pre` version number within the toolcache if this version number is not
+   * found, where `pre` is the prerelease component of this version number.
+   */
+  toolcacheVersion: string;
+}
+
+function computeToolcacheVersion(cliVersion: string, tagName: string): string {
+  return `${cliVersion}-${tagName}`;
+}
+
+/**
+ * Gets version information about the CodeQL bundle which was current as of the release of this
+ * Action.
+ *
+ * This should be used in the following circumstances:
+ *
+ * - When running the Action on Enterprise instances.
+ * - When a user requests `tools: latest`.
+ * - When the Action is running on Dotcom and no default CodeQL version feature flags are enabled.
+ */
+export function getPinnedCodeqlVersion(): CodeqlBundleVersionInfo {
+  return {
+    cliVersion: defaults.cliVersion,
+    tagName: defaults.bundleVersion,
+    toolcacheVersion: computeToolcacheVersion(
+      defaults.cliVersion,
+      defaults.bundleVersion
+    ),
+  };
+}