Handle end-of-support PowerShell with error message

Significantly improves our handling of PowerShell failing to start because it is unsupported.

src/features/UpdatePowerShell.ts

@@ -52,13 +52,18 @@ export class UpdatePowerShell {
         private sessionManager: SessionManager,
         private sessionSettings: Settings,
         private logger: ILogger,
-        versionDetails: IPowerShellVersionDetails) {
+        versionDetails: IPowerShellVersionDetails | SemVer) {
         // We use the commit field as it's like
         // '7.3.0-preview.3-508-g07175ae0ff8eb7306fe0b0fc7d...' which translates
         // to SemVer. The version handler in PSES handles Windows PowerShell and
         // just returns the first three fields like '5.1.22621'.
-        this.localVersion = new SemVer(versionDetails.commit);
-        this.architecture = versionDetails.architecture.toLowerCase();
+        if (versionDetails instanceof SemVer) {
+            this.localVersion = versionDetails;
+            this.architecture = "";
+        } else {
+            this.localVersion = new SemVer(versionDetails.commit);
+            this.architecture = versionDetails.architecture.toLowerCase();
+        }
     }
 
     private shouldCheckForUpdate(): boolean {

src/process.ts

@@ -8,6 +8,8 @@ import { ILogger } from "./logging";
 import Settings = require("./settings");
 import utils = require("./utils");
 import { IEditorServicesSessionDetails } from "./session";
+import { promisify } from "util";
+import { SemVer } from "semver";
 
 export class PowerShellProcess {
     // This is used to warn the user that the extension is taking longer than expected to startup.
@@ -134,6 +136,14 @@ export class PowerShellProcess {
         return sessionDetails;
     }
 
+    // This function should only be used after a failure has occurred because it is slow!
+    public async getVersionCli(): Promise<SemVer> {
+        const exec = promisify(cp.execFile);
+        // TODO: This should have a timeout.
+        const { stdout } = await exec(this.exePath, ["-Login", "-NoProfile", "-NoLogo", "-Command", "$PSVersionTable.PSVersion.ToString()"]);
+        return new SemVer(stdout.trim());
+    }
+
     // Returns the process Id of the consoleTerminal
     public async getPid(): Promise<number | undefined> {
         if (!this.consoleTerminal) { return undefined; }
@@ -148,13 +158,13 @@ export class PowerShellProcess {
         // Clean up the session file
         this.logger.write("Terminating PowerShell process...");
 
-        await PowerShellProcess.deleteSessionFile(this.sessionFilePath);
+        this.consoleTerminal?.dispose();
+        this.consoleTerminal = undefined;
 
         this.consoleCloseSubscription?.dispose();
         this.consoleCloseSubscription = undefined;
 
-        this.consoleTerminal?.dispose();
-        this.consoleTerminal = undefined;
+        await PowerShellProcess.deleteSessionFile(this.sessionFilePath);
     }
 
     public sendKeyPress(): void {

src/session.ts

@@ -24,7 +24,7 @@ import {
     OperatingSystem, PowerShellExeFinder
 } from "./platform";
 import { LanguageClientConsumer } from "./languageClientConsumer";
-import { SemVer } from "semver";
+import { SemVer, satisfies } from "semver";
 
 export enum SessionStatus {
     NeverStarted,
@@ -458,17 +458,36 @@ export class SessionManager implements Middleware {
         try {
             this.sessionDetails = await languageServerProcess.start("EditorServices");
         } catch (err) {
-            this.setSessionFailure("PowerShell process failed to start: ", err instanceof Error ? err.message : "unknown");
+            // We should kill the process in case it's stuck.
+            void languageServerProcess.dispose();
+
+            // PowerShell never started, probably a bad version!
+            const version = await languageServerProcess.getVersionCli();
+            if (version.major === 5) {
+                this.setSessionFailure(
+                    "It looks like you're trying to use Windows PowerShell, which is supported on a best-effort basis. Can you try PowerShell 7?");
+            } else if (satisfies(version, ">=6.0.0 <7.2.0")) {
+                this.setSessionFailure(
+                    `PowerShell ${version} has reached end-of-support, please update! Also see: https://aka.ms/pwsh-support-lifecycle`);
+                const updater = new UpdatePowerShell(this, this.sessionSettings, this.logger, version);
+                // NOTE: We specifically don't want to wait for this.
+                void updater.checkForUpdate();
+            } else {
+                this.setSessionFailure(
+                    "PowerShell process didn't start! Would you like to open an issue?");
+            }
+            return;
         }
 
-        if (this.sessionDetails?.status === "started") {
+        if (this.sessionDetails.status === "started") { // Successful start with a session file
             this.logger.write("Language server started.");
             try {
                 await this.startLanguageClient(this.sessionDetails);
+                return languageServerProcess;
             } catch (err) {
                 this.setSessionFailure("Language client failed to start: ", err instanceof Error ? err.message : "unknown");
             }
-        } else if (this.sessionDetails?.status === "failed") {
+        } else if (this.sessionDetails.status === "failed") { // PowerShell started but indicated it failed
             if (this.sessionDetails.reason === "unsupported") {
                 this.setSessionFailure(
                     "PowerShell language features are only supported on PowerShell version 5.1 and 7+. " +
@@ -483,10 +502,8 @@ export class SessionManager implements Middleware {
             }
         } else {
             this.setSessionFailure(
-                `Unknown session status '${this.sessionDetails?.status}' with reason '${this.sessionDetails?.reason}`);
+                `Unknown session status '${this.sessionDetails.status}' with reason '${this.sessionDetails.reason}`);
         }
-
-        return languageServerProcess;
     }
 
     private async findPowerShell(): Promise<IPowerShellExeDetails | undefined> {