Revert "Remove old code for folder support in interpreter path settin…

…g" (#22638)

Reverts #22413
#22618

Turns out we still need this code for old deprecated APIs that we
expose, one of which is used in testing.

src/client/common/configSettings.ts

@@ -2,6 +2,7 @@
 
 // eslint-disable-next-line camelcase
 import * as path from 'path';
+import * as fs from 'fs';
 import {
  ConfigurationChangeEvent,
  ConfigurationTarget,
@@ -35,6 +36,8 @@ import {
 } from './types';
 import { debounceSync } from './utils/decorators';
 import { SystemVariables } from './variables/systemVariables';
+import { getOSType, OSType } from './utils/platform';
+import { isWindows } from './platform/platformService';
 
 const untildify = require('untildify');
 
@@ -391,7 +394,7 @@ export class PythonSettings implements IPythonSettings {
 
  // eslint-disable-next-line class-methods-use-this
  protected getPythonExecutable(pythonPath: string): string {
- return untildify(pythonPath);
+ return getPythonExecutable(pythonPath);
  }
 
  protected onWorkspaceFoldersChanged(): void {
@@ -490,3 +493,63 @@ function getAbsolutePath(pathToCheck: string, rootDir: string | undefined): stri
  }
  return path.isAbsolute(pathToCheck) ? pathToCheck : path.resolve(rootDir, pathToCheck);
 }
+
+function getPythonExecutable(pythonPath: string): string {
+ pythonPath = untildify(pythonPath) as string;
+
+ // If only 'python'.
+ if (
+ pythonPath === 'python' ||
+ pythonPath.indexOf(path.sep) === -1 ||
+ path.basename(pythonPath) === path.dirname(pythonPath)
+ ) {
+ return pythonPath;
+ }
+
+ if (isValidPythonPath(pythonPath)) {
+ return pythonPath;
+ }
+ // Keep python right on top, for backwards compatibility.
+
+ const KnownPythonExecutables = [
+ 'python',
+ 'python4',
+ 'python3.6',
+ 'python3.5',
+ 'python3',
+ 'python2.7',
+ 'python2',
+ 'python3.7',
+ 'python3.8',
+ 'python3.9',
+ ];
+
+ for (let executableName of KnownPythonExecutables) {
+ // Suffix with 'python' for linux and 'osx', and 'python.exe' for 'windows'.
+ if (isWindows()) {
+ executableName = `${executableName}.exe`;
+ if (isValidPythonPath(path.join(pythonPath, executableName))) {
+ return path.join(pythonPath, executableName);
+ }
+ if (isValidPythonPath(path.join(pythonPath, 'Scripts', executableName))) {
+ return path.join(pythonPath, 'Scripts', executableName);
+ }
+ } else {
+ if (isValidPythonPath(path.join(pythonPath, executableName))) {
+ return path.join(pythonPath, executableName);
+ }
+ if (isValidPythonPath(path.join(pythonPath, 'bin', executableName))) {
+ return path.join(pythonPath, 'bin', executableName);
+ }
+ }
+ }
+
+ return pythonPath;
+}
+
+function isValidPythonPath(pythonPath: string): boolean {
+ return (
+ fs.existsSync(pythonPath) &&
+ path.basename(getOSType() === OSType.Windows ? pythonPath.toLowerCase() : pythonPath).startsWith('python')
+ );
+}