Document order-dependence of isLocal flag (#49959)

Author: amcasey

src/server/session.ts

@@ -344,6 +344,8 @@ namespace ts.server {
     function getDefinitionLocation(defaultProject: Project, initialLocation: DocumentPosition, isForRename: boolean): DocumentPosition | undefined {
         const infos = defaultProject.getLanguageService().getDefinitionAtPosition(initialLocation.fileName, initialLocation.pos, /*searchOtherFilesOnly*/ false, /*stopAtAlias*/ isForRename);
         const info = infos && firstOrUndefined(infos);
+        // Note that the value of `isLocal` may depend on whether or not the checker has run on the containing file
+        // (implying that FAR cascading behavior may depend on request order)
         return info && !info.isLocal ? { fileName: info.fileName, pos: info.textSpan.start } : undefined;
     }
 

src/services/types.ts

@@ -1045,7 +1045,12 @@ namespace ts {
         containerKind: ScriptElementKind;
         containerName: string;
         unverified?: boolean;
-        /* @internal */ isLocal?: boolean;
+        /** @internal
+         * Initially, this value is determined syntactically, but it is updated by the checker to cover
+         * cases like declarations that are exported in subsequent statements.  As a result, the value
+         * may be "incomplete" if this span has yet to be checked.
+         */
+        isLocal?: boolean;
         /* @internal */ isAmbient?: boolean;
         /* @internal */ failedAliasResolution?: boolean;
     }