Skip unnecessary py.typed file exist checks. (microsoft#7652)

* skip unnecessary py.typed file exist checks.

* passed wrong uri

* PR feedbacks

* more comments

* PR feedbacks

packages/pyright-internal/src/analyzer/importResolver.ts

@@ -16,8 +16,8 @@ import { Host } from '../common/host';
 import { stubsSuffix } from '../common/pathConsts';
 import { stripFileExtension } from '../common/pathUtils';
 import { PythonVersion, pythonVersion3_0 } from '../common/pythonVersion';
-import { ServiceProvider } from '../common/serviceProvider';
 import { ServiceKeys } from '../common/serviceKeys';
+import { ServiceProvider } from '../common/serviceProvider';
 import * as StringUtils from '../common/stringUtils';
 import { equateStringsCaseInsensitive } from '../common/stringUtils';
 import { Uri } from '../common/uri/uri';
@@ -26,7 +26,7 @@ import { isIdentifierChar, isIdentifierStartChar } from '../parser/characters';
 import { ImplicitImport, ImportResult, ImportType } from './importResult';
 import { getDirectoryLeadingDotsPointsTo } from './importStatementUtils';
 import { ImportPath, ParentDirectoryCache } from './parentDirectoryCache';
-import { PyTypedInfo, getPyTypedInfo } from './pyTypedUtils';
+import { PyTypedInfo, getPyTypedInfoForPyTypedFile } from './pyTypedUtils';
 import * as PythonPathUtils from './pythonPathUtils';
 import * as SymbolNameUtils from './symbolNameUtils';
 import { isDunderName } from './symbolNameUtils';
@@ -2708,7 +2708,8 @@ export class ImportResolver {
         if (!this.fileExistsCached(filePath.pytypedUri)) {
             return undefined;
         }
-        return getPyTypedInfo(this.fileSystem, filePath);
+
+        return getPyTypedInfoForPyTypedFile(this.fileSystem, filePath.pytypedUri);
     }
 
     private _resolveNativeModuleStub(

packages/pyright-internal/src/analyzer/pyTypedUtils.ts

@@ -16,18 +16,32 @@ export interface PyTypedInfo {
     isPartiallyTyped: boolean;
 }
 
+//
+// Retrieves information about a py.typed file, if it exists, under the given path.
+//
 export function getPyTypedInfo(fileSystem: FileSystem, dirPath: Uri): PyTypedInfo | undefined {
     if (!fileSystem.existsSync(dirPath) || !isDirectory(fileSystem, dirPath)) {
         return undefined;
     }
 
-    let isPartiallyTyped = false;
     const pyTypedPath = dirPath.pytypedUri;
-
     if (!fileSystem.existsSync(pyTypedPath) || !isFile(fileSystem, pyTypedPath)) {
         return undefined;
     }
 
+    return getPyTypedInfoForPyTypedFile(fileSystem, pyTypedPath);
+}
+
+//
+// Retrieves information about a py.typed file. The pyTypedPath provided must be a valid path.
+//
+export function getPyTypedInfoForPyTypedFile(fileSystem: FileSystem, pyTypedPath: Uri) {
+    // This function intentionally doesn't check whether the given py.typed path exists or not,
+    // as filesystem access is expensive if done repeatedly.
+    // The caller should verify the file's validity before calling this method and use a cache if possible
+    // to avoid high filesystem access costs.
+    let isPartiallyTyped = false;
+
     // Read the contents of the file as text.
     const fileStats = fileSystem.statSync(pyTypedPath);