Tweak module resolution failed lookup watching

src/compiler/path.ts

@@ -451,6 +451,9 @@ function pathComponents(path: string, rootLength: number) {
     return [root, ...rest];
 }
 
+/** @internal */
+export type PathPathComponents = Path[] & { __pathComponensBrand: any };
+
 /**
  * Parse a path into an array containing a root component (at index 0) and zero or more path
  * components (at indices > 0). The result is not normalized.
@@ -484,6 +487,9 @@ function pathComponents(path: string, rootLength: number) {
  *
  * @internal
  */
+export function getPathComponents(path: Path): PathPathComponents;
+/** @internal */
+export function getPathComponents(path: string, currentDirectory?: string): string[];
 export function getPathComponents(path: string, currentDirectory = "") {
     path = combinePaths(currentDirectory, path);
     return pathComponents(path, getRootLength(path));
@@ -501,11 +507,11 @@ export function getPathComponents(path: string, currentDirectory = "") {
  *
  * @internal
  */
-export function getPathFromPathComponents(pathComponents: readonly string[]) {
-    if (pathComponents.length === 0) return "";
+export function getPathFromPathComponents<T extends string>(pathComponents: readonly T[], length?: number) {
+    if (pathComponents.length === 0) return "" as T;
 
     const root = pathComponents[0] && ensureTrailingDirectorySeparator(pathComponents[0]);
-    return root + pathComponents.slice(1).join(directorySeparator);
+    return root + pathComponents.slice(1, length).join(directorySeparator) as T;
 }
 
 //// Path Normalization

src/server/editorServices.ts

@@ -54,6 +54,7 @@ import {
     getFileNamesFromConfigSpecs,
     getFileWatcherEventKind,
     getNormalizedAbsolutePath,
+    getPathComponents,
     getSnapshotText,
     getWatchFactory,
     hasExtension,
@@ -1892,7 +1893,7 @@ export class ProjectService {
             // created when any of the script infos are added as root of inferred project
             if (this.configFileExistenceImpactsRootOfInferredProject(configFileExistenceInfo)) {
                 // If we cannot watch config file existence without configured project, close the configured file watcher
-                if (!canWatchDirectoryOrFile(getDirectoryPath(canonicalConfigFilePath) as Path)) {
+                if (!canWatchDirectoryOrFile(getPathComponents(getDirectoryPath(canonicalConfigFilePath) as Path))) {
                     configFileExistenceInfo.watcher!.close();
                     configFileExistenceInfo.watcher = noopConfigFileWatcher;
                 }
@@ -1979,7 +1980,7 @@ export class ProjectService {
             (configFileExistenceInfo.openFilesImpactedByConfigFile ||= new Map()).set(info.path, true);
 
             // If there is no configured project for this config file, add the file watcher
-            configFileExistenceInfo.watcher ||= canWatchDirectoryOrFile(getDirectoryPath(canonicalConfigFilePath) as Path) ?
+            configFileExistenceInfo.watcher ||= canWatchDirectoryOrFile(getPathComponents(getDirectoryPath(canonicalConfigFilePath) as Path)) ?
                 this.watchFactory.watchFile(
                     configFileName,
                     (_filename, eventKind) => this.onConfigFileChanged(canonicalConfigFilePath, eventKind),
@@ -2703,12 +2704,12 @@ export class ProjectService {
         }
 
         // Single inferred project does not have a project root and hence no current directory
-        return this.createInferredProject(/*currentDirectory*/ undefined, /*isSingleInferredProject*/ true);
+        return this.createInferredProject("", /*isSingleInferredProject*/ true);
     }
 
-    private getOrCreateSingleInferredWithoutProjectRoot(currentDirectory: string | undefined): InferredProject {
+    private getOrCreateSingleInferredWithoutProjectRoot(currentDirectory: string): InferredProject {
         Debug.assert(!this.useSingleInferredProject);
-        const expectedCurrentDirectory = this.toCanonicalFileName(this.getNormalizedAbsolutePath(currentDirectory || ""));
+        const expectedCurrentDirectory = this.toCanonicalFileName(this.getNormalizedAbsolutePath(currentDirectory));
         // Reuse the project with same current directory but no roots
         for (const inferredProject of this.inferredProjects) {
             if (!inferredProject.projectRootPath &&
@@ -2721,7 +2722,7 @@ export class ProjectService {
         return this.createInferredProject(currentDirectory);
     }
 
-    private createInferredProject(currentDirectory: string | undefined, isSingleInferredProject?: boolean, projectRootPath?: NormalizedPath): InferredProject {
+    private createInferredProject(currentDirectory: string, isSingleInferredProject?: boolean, projectRootPath?: NormalizedPath): InferredProject {
         const compilerOptions = projectRootPath && this.compilerOptionsForInferredProjectsPerProjectRoot.get(projectRootPath) || this.compilerOptionsForInferredProjects!; // TODO: GH#18217
         let watchOptionsAndErrors: WatchOptionsAndErrors | false | undefined;
         let typeAcquisition: TypeAcquisition | undefined;

src/server/project.ts

@@ -465,11 +465,11 @@ export abstract class Project implements LanguageServiceHost, ModuleResolutionHo
         public compileOnSaveEnabled: boolean,
         protected watchOptions: WatchOptions | undefined,
         directoryStructureHost: DirectoryStructureHost,
-        currentDirectory: string | undefined,
+        currentDirectory: string,
     ) {
         this.projectName = projectName;
         this.directoryStructureHost = directoryStructureHost;
-        this.currentDirectory = this.projectService.getNormalizedAbsolutePath(currentDirectory || "");
+        this.currentDirectory = this.projectService.getNormalizedAbsolutePath(currentDirectory);
         this.getCanonicalFileName = this.projectService.toCanonicalFileName;
 
         this.cancellationToken = new ThrottledCancellationToken(this.projectService.cancellationToken, this.projectService.throttleWaitMilliseconds);
@@ -514,7 +514,7 @@ export abstract class Project implements LanguageServiceHost, ModuleResolutionHo
         // Use the current directory as resolution root only if the project created using current directory string
         this.resolutionCache = createResolutionCache(
             this,
-            currentDirectory && this.currentDirectory,
+            this.currentDirectory,
             /*logChangesWhenResolvingModule*/ true
         );
         this.languageService = createLanguageService(this, this.documentRegistry, this.projectService.serverMode);
@@ -2059,7 +2059,7 @@ export abstract class Project implements LanguageServiceHost, ModuleResolutionHo
     getNoDtsResolutionProject(rootFileNames: readonly string[]): Project {
         Debug.assert(this.projectService.serverMode === LanguageServiceMode.Semantic);
         if (!this.noDtsResolutionProject) {
-            this.noDtsResolutionProject = new AuxiliaryProject(this.projectService, this.documentRegistry, this.getCompilerOptionsForNoDtsResolutionProject());
+            this.noDtsResolutionProject = new AuxiliaryProject(this.projectService, this.documentRegistry, this.getCompilerOptionsForNoDtsResolutionProject(), this.currentDirectory);
         }
 
         enumerateInsertsAndDeletes<NormalizedPath, NormalizedPath>(
@@ -2176,7 +2176,7 @@ export class InferredProject extends Project {
         compilerOptions: CompilerOptions,
         watchOptions: WatchOptions | undefined,
         projectRootPath: NormalizedPath | undefined,
-        currentDirectory: string | undefined,
+        currentDirectory: string,
         pluginConfigOverrides: Map<string, any> | undefined,
         typeAcquisition: TypeAcquisition | undefined) {
         super(projectService.newInferredProjectName(),
@@ -2246,7 +2246,7 @@ export class InferredProject extends Project {
 }
 
 class AuxiliaryProject extends Project {
-    constructor(projectService: ProjectService, documentRegistry: DocumentRegistry, compilerOptions: CompilerOptions) {
+    constructor(projectService: ProjectService, documentRegistry: DocumentRegistry, compilerOptions: CompilerOptions, currentDirectory: string) {
         super(projectService.newAuxiliaryProjectName(),
             ProjectKind.Auxiliary,
             projectService,
@@ -2257,7 +2257,7 @@ class AuxiliaryProject extends Project {
             /*compileOnSaveEnabled*/ false,
             /*watchOptions*/ undefined,
             projectService.host,
-            /*currentDirectory*/ undefined);
+            currentDirectory);
     }
 
     override isOrphan(): boolean {

src/services/rename.ts

@@ -166,7 +166,7 @@ function wouldRenameInOtherNodeModules(
 }
 
 function getPackagePathComponents(filePath: Path): string[] | undefined {
-    const components = getPathComponents(filePath);
+    const components = getPathComponents(filePath) as string[];
     const nodeModulesIdx = components.lastIndexOf("node_modules");
     if (nodeModulesIdx === -1) {
         return undefined;

src/testRunner/unittests/canWatch.ts

@@ -14,7 +14,7 @@ describe("unittests:: canWatch::", () => {
             paths.forEach(path => baselineCanWatchDirectoryOrFile(combinePaths(path, "package.json"), maxLengths));
             baseline.push("", "");
             function baselineCanWatchDirectoryOrFile(path: ts.Path, maxLengths: readonly number[]) {
-                pushRow(baseline, [path, `${ts.canWatchDirectoryOrFile(path)}`], maxLengths);
+                pushRow(baseline, [path, `${ts.canWatchDirectoryOrFile(ts.getPathComponents(path))}`], maxLengths);
             }
         },
     );
@@ -25,13 +25,12 @@ describe("unittests:: canWatch::", () => {
         (paths, longestPathLength, baseline) => {
             const testType = "canWatchAtTypes";
             const maxLengths = [longestPathLength + "/node_modules/@types".length, testType.length] as const;
-            baselineCanWatchForRoot(paths, baseline, root => {
-                pushHeader(baseline, ["Directory", testType], maxLengths);
-                paths.forEach(path => {
-                    path = combinePaths(path, "node_modules/@types");
-                    pushRow(baseline, [path, `${ts.canWatchAtTypes(path, root)}`], maxLengths);
-                });
+            pushHeader(baseline, ["Directory", testType], maxLengths);
+            paths.forEach(path => {
+                path = combinePaths(path, "node_modules/@types");
+                pushRow(baseline, [path, `${ts.canWatchAtTypes(path)}`], maxLengths);
             });
+            baseline.push("", "");
         },
     );
 
@@ -41,13 +40,12 @@ describe("unittests:: canWatch::", () => {
         (paths, longestPathLength, baseline) => {
             const testType = "canWatchAffectingLocation";
             const maxLengths = [longestPathLength + "/package.json".length, testType.length] as const;
-            baselineCanWatchForRoot(paths, baseline, _root => {
-                pushHeader(baseline, ["File", testType], maxLengths);
-                paths.forEach(path => {
-                    path = combinePaths(path, "package.json");
-                    pushRow(baseline, [path, `${ts.canWatchAffectingLocation(path)}`], maxLengths);
-                });
+            pushHeader(baseline, ["File", testType], maxLengths);
+            paths.forEach(path => {
+                path = combinePaths(path, "package.json");
+                pushRow(baseline, [path, `${ts.canWatchAffectingLocation(path)}`], maxLengths);
             });
+            baseline.push("", "");
         },
     );
 
@@ -65,21 +63,21 @@ describe("unittests:: canWatch::", () => {
                 const recursive = "Recursive";
                 const maxLength = longestPathLength + ts.combinePaths(forPath, "dir/subdir/somefile.d.ts").length;
                 const maxLengths = [maxLength, maxLength, recursive.length] as const;
-                baselineCanWatchForRoot(paths, baseline, root => {
+                baselineCanWatchForRoot(paths, baseline, (rootPathCompoments, root) => {
                     pushHeader(baseline, ["Location", "getDirectoryToWatchFailedLookupLocation", recursive], maxLengths);
                     paths.forEach(path => {
-                        baselineGetDirectoryToWatchFailedLookupLocation(combinePaths(path, forPath, "somefile.d.ts"), root, maxLengths);
-                        baselineGetDirectoryToWatchFailedLookupLocation(combinePaths(path, forPath, "dir/somefile.d.ts"), root, maxLengths);
-                        baselineGetDirectoryToWatchFailedLookupLocation(combinePaths(path, forPath, "dir/subdir/somefile.d.ts"), root, maxLengths);
+                        baselineGetDirectoryToWatchFailedLookupLocation(combinePaths(path, forPath, "somefile.d.ts"), root, rootPathCompoments, maxLengths);
+                        baselineGetDirectoryToWatchFailedLookupLocation(combinePaths(path, forPath, "dir/somefile.d.ts"), root, rootPathCompoments, maxLengths);
+                        baselineGetDirectoryToWatchFailedLookupLocation(combinePaths(path, forPath, "dir/subdir/somefile.d.ts"), root, rootPathCompoments, maxLengths);
                     });
                 });
-                function baselineGetDirectoryToWatchFailedLookupLocation(path: ts.Path, root: ts.Path | undefined, maxLengths: readonly number[]) {
+                function baselineGetDirectoryToWatchFailedLookupLocation(path: ts.Path, root: ts.Path, rootPathCompoments: Readonly<ts.PathPathComponents>, maxLengths: readonly number[]) {
                     const result = ts.getDirectoryToWatchFailedLookupLocation(
                         path,
                         path,
                         root,
                         root,
-                        root !== undefined ? root.split(ts.directorySeparator).length : 0,
+                        rootPathCompoments,
                         ts.returnUndefined,
                     );
                     pushRow(baseline, [path, result ? result.dir : "", result ? `${!result.nonRecursive}` : ""], maxLengths);
@@ -94,16 +92,18 @@ describe("unittests:: canWatch::", () => {
         (paths, longestPathLength, baseline) => {
             const maxLength = longestPathLength + "/node_modules/@types".length;
             const maxLengths = [maxLength, maxLength] as const;
-            baselineCanWatchForRoot(paths, baseline, root => {
+            baselineCanWatchForRoot(paths, baseline, (rootPathCompoments, root) => {
                 pushHeader(baseline, ["Directory", "getDirectoryToWatchFailedLookupLocationFromTypeRoot"], maxLengths);
                 paths.forEach(path => {
                     path = combinePaths(path, "node_modules/@types");
                     // This is invoked only on paths that are watched
-                    if (!ts.canWatchAtTypes(path, root)) return;
+                    if (!ts.canWatchAtTypes(path)) return;
                     const result = ts.getDirectoryToWatchFailedLookupLocationFromTypeRoot(
                         path,
                         path,
                         root,
+                        rootPathCompoments,
+                        ts.returnUndefined,
                         ts.returnTrue,
                     );
                     pushRow(baseline, [path, result !== undefined ? result : ""], maxLengths);
@@ -112,16 +112,14 @@ describe("unittests:: canWatch::", () => {
         },
     );
 
-    function baselineCanWatchForRoot(paths: readonly ts.Path[], baseline: string[], baselineForRoot: (root: ts.Path | undefined) => void) {
-        paths.forEach(baselineRoot);
-        baselineRoot(/*rootDirForResolution*/ undefined);
-        baseline.push("", "");
-
-        function baselineRoot(rootDirForResolution: ts.Path | undefined) {
+    function baselineCanWatchForRoot(paths: readonly ts.Path[], baseline: string[], baselineForRoot: (rootPathCompoments: Readonly<ts.PathPathComponents>, root: ts.Path) => void) {
+        paths.forEach(rootDirForResolution => {
             const root = ts.getRootDirectoryOfResolutionCache(rootDirForResolution, ts.returnUndefined) as ts.Path;
-            baseline.push("", `## RootDirForResolution: ${rootDirForResolution}`, "", `Root: ${root}`);
-            baselineForRoot(root);
-        }
+            assert(root === rootDirForResolution);
+            baseline.push("", `## RootDirForResolution: ${rootDirForResolution}`);
+            baselineForRoot(ts.getPathComponents(root), root);
+        });
+        baseline.push("", "");
     }
 
     function baselineCanWatch(