Avoid a symlinked package globally importing itself (fixes another case of #26044)

Author: Andy Hanson

src/compiler/moduleSpecifiers.ts

@@ -17,7 +17,7 @@ namespace ts.moduleSpecifiers {
         redirectTargetsMap: RedirectTargetsMap,
     ): string {
         const info = getInfo(compilerOptions, importingSourceFile, importingSourceFileName, host);
-        const modulePaths = getAllModulePaths(files, toFileName, info.getCanonicalFileName, host, redirectTargetsMap);
+        const modulePaths = getAllModulePaths(files, importingSourceFileName, toFileName, info.getCanonicalFileName, host, redirectTargetsMap);
         return firstDefined(modulePaths, moduleFileName => getGlobalModuleSpecifier(moduleFileName, info, host, compilerOptions)) ||
             first(getLocalModuleSpecifiers(toFileName, info, compilerOptions, preferences));
     }
@@ -40,7 +40,7 @@ namespace ts.moduleSpecifiers {
             return Debug.fail("Files list must be present to resolve symlinks in specifier resolution");
         }
         const moduleSourceFile = getSourceFileOfNode(moduleSymbol.valueDeclaration);
-        const modulePaths = getAllModulePaths(files, moduleSourceFile.fileName, info.getCanonicalFileName, host, redirectTargetsMap);
+        const modulePaths = getAllModulePaths(files, importingSourceFile.path, moduleSourceFile.fileName, info.getCanonicalFileName, host, redirectTargetsMap);
 
         const global = mapDefined(modulePaths, moduleFileName => getGlobalModuleSpecifier(moduleFileName, info, host, compilerOptions));
         return global.length ? global.map(g => [g]) : modulePaths.map(moduleFileName =>
@@ -176,7 +176,7 @@ namespace ts.moduleSpecifiers {
      * Looks for existing imports that use symlinks to this module.
      * Symlinks will be returned first so they are preferred over the real path.
      */
-    function getAllModulePaths(files: ReadonlyArray<SourceFile>, importedFileName: string, getCanonicalFileName: (file: string) => string, host: ModuleSpecifierResolutionHost, redirectTargetsMap: RedirectTargetsMap): ReadonlyArray<string> {
+    function getAllModulePaths(files: ReadonlyArray<SourceFile>, importingFileName: string, importedFileName: string, getCanonicalFileName: GetCanonicalFileName, host: ModuleSpecifierResolutionHost, redirectTargetsMap: RedirectTargetsMap): ReadonlyArray<string> {
         const redirects = redirectTargetsMap.get(importedFileName);
         const importedFileNames = redirects ? [...redirects, importedFileName] : [importedFileName];
         const cwd = host.getCurrentDirectory ? host.getCurrentDirectory() : "";
@@ -186,6 +186,10 @@ namespace ts.moduleSpecifiers {
         const result: string[] = [];
         const compareStrings = (!host.useCaseSensitiveFileNames || host.useCaseSensitiveFileNames()) ? compareStringsCaseSensitive : compareStringsCaseInsensitive;
         links.forEach((resolved, path) => {
+            if (startsWithDirectory(importingFileName, resolved, getCanonicalFileName)) {
+                return; // Don't want to a package to globally import from itself
+            }
+
             const target = targets.find(t => compareStrings(t.slice(0, resolved.length + 1), resolved + "/") === Comparison.EqualTo);
             if (target === undefined) return;
 

src/compiler/utilities.ts

@@ -7157,6 +7157,12 @@ namespace ts {
         return path.slice(0, Math.max(rootLength, path.lastIndexOf(directorySeparator)));
     }
 
+    export function startsWithDirectory(fileName: string, directoryName: string, getCanonicalFileName: GetCanonicalFileName): boolean {
+        const canonicalFileName = getCanonicalFileName(fileName);
+        const canonicalDirectoryName = getCanonicalFileName(directoryName);
+        return startsWith(canonicalFileName, canonicalDirectoryName + "/") || startsWith(canonicalFileName, canonicalDirectoryName + "\\");
+    }
+
     export function isUrl(path: string) {
         return getEncodedRootLength(path) < 0;
     }

tests/cases/fourslash/importNameCodeFix_symlink_own_package_2.ts

@@ -0,0 +1,17 @@
+/// <reference path="fourslash.ts" />
+
+// @Filename: /packages/a/test.ts
+// @Symlink: /node_modules/a/test.ts
+////x;
+
+// @Filename: /packages/a/utils.ts
+// @Symlink: /node_modules/a/utils.ts
+////import {} from "a/utils";
+////export const x = 0;
+
+goTo.file("/packages/a/test.ts");
+verify.importFixAtPosition([
+`import { x } from "./utils";
+
+x;`,
+]);