Add disabled by env var disablement reason

Author: henrymercer

lib/init-action.js

@@ -1139,6 +1139,7 @@ test(
   {
     overlayDatabaseMode: OverlayDatabaseMode.None,
     useOverlayDatabaseCaching: false,
+    disabledReason: OverlayDisabledReason.DisabledByEnvironmentVariable,
   },
 );
 

src/config-utils.test.ts

@@ -844,6 +844,11 @@ export async function getOverlayDatabaseMode(
       `Setting overlay database mode to ${modeEnv} ` +
         "from the CODEQL_OVERLAY_DATABASE_MODE environment variable.",
     );
+    if (modeEnv === OverlayDatabaseMode.None) {
+      return disabledResult(
+        OverlayDisabledReason.DisabledByEnvironmentVariable,
+      );
+    }
     return validateOverlayDatabaseMode(
       modeEnv,
       false,
@@ -959,7 +964,7 @@ export async function getOverlayDatabaseMode(
  * appropriate disabled reason.
  */
 async function validateOverlayDatabaseMode(
-  overlayDatabaseMode: OverlayDatabaseMode,
+  overlayDatabaseMode: Exclude<OverlayDatabaseMode, OverlayDatabaseMode.None>,
   useOverlayDatabaseCaching: boolean,
   codeql: CodeQL,
   languages: Language[],
@@ -978,14 +983,6 @@ async function validateOverlayDatabaseMode(
     disabledReason: reason,
   });
 
-  if (overlayDatabaseMode === OverlayDatabaseMode.None) {
-    return {
-      overlayDatabaseMode: OverlayDatabaseMode.None,
-      useOverlayDatabaseCaching: false,
-      disabledReason: undefined,
-    };
-  }
-
   if (
     buildMode !== BuildMode.None &&
     (

src/config-utils.ts

@@ -10,6 +10,8 @@ import { RepositoryPropertyName } from "../feature-flags/properties";
 
 /** Reason why overlay analysis was disabled. */
 export enum OverlayDisabledReason {
+  /** Overlay analysis was disabled by the CODEQL_OVERLAY_DATABASE_MODE environment variable being set to "none". */
+  DisabledByEnvironmentVariable = "disabled-by-environment-variable",
   /** Overlay analysis was disabled by a repository property. */
   DisabledByRepositoryProperty = "disabled-by-repository-property",
   /** The build mode is incompatible with overlay analysis. */