support per file debug with correct interpreter

Author: eleanorjboyd

src/extension/debugger/configuration/debugConfigurationService.ts

@@ -1,8 +1,8 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
-
+import * as fs from 'fs';
 import { cloneDeep } from 'lodash';
-import { CancellationToken, DebugConfiguration, QuickPickItem, WorkspaceFolder } from 'vscode';
+import { CancellationToken, DebugConfiguration, QuickPickItem, Uri, WorkspaceFolder } from 'vscode';
 import { DebugConfigStrings } from '../../common/utils/localize';
 import { IMultiStepInputFactory, InputStep, IQuickPickParameters, MultiStepInput } from '../../common/multiStepInput';
 import { AttachRequestArguments, DebugConfigurationArguments, LaunchRequestArguments } from '../../types';
@@ -17,6 +17,7 @@ import { buildPyramidLaunchConfiguration } from './providers/pyramidLaunch';
 import { buildRemoteAttachConfiguration } from './providers/remoteAttach';
 import { IDebugConfigurationResolver } from './types';
 import { buildFileWithArgsLaunchDebugConfiguration } from './providers/fileLaunchWithArgs';
+import { getInterpreterDetails } from '../../common/python';
 
 export class PythonDebugConfigurationService implements IDebugConfigurationService {
     private cacheDebugConfig: DebugConfiguration | undefined = undefined;
@@ -90,6 +91,18 @@ export class PythonDebugConfigurationService implements IDebugConfigurationServi
         debugConfiguration: DebugConfiguration,
         token?: CancellationToken,
     ): Promise<DebugConfiguration | undefined> {
+        // now that ${file} is resolved, we can use it to get the interpreter for that file
+        if (debugConfiguration.program !== undefined) {
+            if (debugConfiguration.python === undefined) {
+                // If program is a valid file, get interpreter for that file
+                if (fs.existsSync(debugConfiguration.program) && fs.statSync(debugConfiguration.program).isFile()) {
+                    const interpreter = await getInterpreterDetails(Uri.file(debugConfiguration.program));
+                    if (interpreter?.path && interpreter.path.length > 0) {
+                        debugConfiguration.python = interpreter.path[0];
+                    }
+                }
+            }
+        }
         function resolve<T extends DebugConfiguration>(resolver: IDebugConfigurationResolver<T>) {
             return resolver.resolveDebugConfigurationWithSubstitutedVariables(folder, debugConfiguration as T, token);
         }

src/extension/debugger/configuration/resolvers/base.ts

@@ -2,7 +2,7 @@
 // Licensed under the MIT License.
 
 'use strict';
-
+import * as fs from 'fs';
 import * as path from 'path';
 import { CancellationToken, DebugConfiguration, Uri, WorkspaceFolder } from 'vscode';
 import { sendTelemetryEvent } from '../../../telemetry';
@@ -137,9 +137,22 @@ export abstract class BaseConfigurationResolver<T extends DebugConfiguration>
         if (!debugConfiguration) {
             return;
         }
+        let interpreterDetailsTarget = workspaceFolder;
 
-        // get the interpreter details in the context of the workspace folder
-        const interpreterDetail = await getInterpreterDetails(workspaceFolder);
+        if (debugConfiguration.program !== undefined) {
+            if (debugConfiguration.python === undefined) {
+                if (debugConfiguration.program === '${file}') {
+                    // If program is ${file}, we cannot determine the interpreter yet
+                    return;
+                }
+                // If program is a valid file, get interpreter for that file
+                if (fs.existsSync(debugConfiguration.program) && fs.statSync(debugConfiguration.program).isFile()) {
+                    interpreterDetailsTarget = Uri.file(debugConfiguration.program);
+                }
+            }
+        }
+        // get the interpreter details in the context of either the workspace folder or the program file
+        const interpreterDetail = await getInterpreterDetails(interpreterDetailsTarget);
         const interpreterPath = interpreterDetail?.path ?? (await getSettingsPythonPath(workspaceFolder));
         const resolvedInterpreterPath = interpreterPath ? interpreterPath[0] : interpreterPath;