[Lldb-commits] [lldb] [lldb-dap][vscode][windows] check if Python is installed properly before starting lldb-dap (PR #181124)

[Charles Zablit via lldb-commits]

https://github.com/charles-zablit updated https://github.com/llvm/llvm-project/pull/181124

>From 0a348776b7fda66d3de2ae1e0fc62ce15e5db173 Mon Sep 17 00:00:00 2001
From: Charles Zablit <c_zablit at apple.com>
Date: Thu, 12 Feb 2026 13:01:36 +0100
Subject: [PATCH 1/3] [lldb-dap][vscode][windows] check if Python is installed
 properly before starting lldb-dap

---
 lldb/tools/lldb-dap/extension/src/lldb-dap-server.ts | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lldb/tools/lldb-dap/extension/src/lldb-dap-server.ts b/lldb/tools/lldb-dap/extension/src/lldb-dap-server.ts
index deacdea145a41..53eaac92d1286 100644
--- a/lldb/tools/lldb-dap/extension/src/lldb-dap-server.ts
+++ b/lldb/tools/lldb-dap/extension/src/lldb-dap-server.ts
@@ -2,6 +2,7 @@ import { FSWatcher, watch as chokidarWatch } from "chokidar";
 import * as child_process from "node:child_process";
 import { isDeepStrictEqual } from "util";
 import * as vscode from "vscode";
+import * as os from "os";
 
 /**
  * Represents a running lldb-dap process that is accepting connections (i.e. in "server mode").
@@ -60,6 +61,15 @@ export class LLDBDapServer implements vscode.Disposable {
     }
 
     this.serverInfo = new Promise((resolve, reject) => {
+      if (os.platform() === "win32") {
+        const pythonCheckProcess = child_process.spawnSync(dapPath, ["--check-python"]);
+        if (pythonCheckProcess.stderr) {
+          vscode.window.showErrorMessage(
+            `Python is not installed correctly. Please install it to use lldb-dap.\n${pythonCheckProcess.stderr}`
+          );
+          return;
+        }
+      }
       const process = child_process.spawn(dapPath, dapArgs, options);
       process.on("error", (error) => {
         reject(error);

>From 4cab18e1a610bf650510a0dd2e5f7d92baa8489d Mon Sep 17 00:00:00 2001
From: Charles Zablit <c_zablit at apple.com>
Date: Wed, 29 Apr 2026 12:12:24 +0100
Subject: [PATCH 2/3] fixup! [lldb-dap][vscode][windows] check if Python is
 installed properly before starting lldb-dap

---
 .../lldb-dap/extension/src/lldb-dap-server.ts | 25 ++++++++++++-------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/lldb/tools/lldb-dap/extension/src/lldb-dap-server.ts b/lldb/tools/lldb-dap/extension/src/lldb-dap-server.ts
index 53eaac92d1286..0e9edd44eb76b 100644
--- a/lldb/tools/lldb-dap/extension/src/lldb-dap-server.ts
+++ b/lldb/tools/lldb-dap/extension/src/lldb-dap-server.ts
@@ -60,16 +60,23 @@ export class LLDBDapServer implements vscode.Disposable {
       return this.serverInfo;
     }
 
-    this.serverInfo = new Promise((resolve, reject) => {
-      if (os.platform() === "win32") {
-        const pythonCheckProcess = child_process.spawnSync(dapPath, ["--check-python"]);
-        if (pythonCheckProcess.stderr) {
-          vscode.window.showErrorMessage(
-            `Python is not installed correctly. Please install it to use lldb-dap.\n${pythonCheckProcess.stderr}`
-          );
-          return;
-        }
+    if (os.platform() === "win32") {
+      const pythonCheckProcess = child_process.spawnSync(dapPath, [
+        "--check-python",
+      ]);
+      if (pythonCheckProcess.status !== 0) {
+        await vscode.window.showErrorMessage(
+          "Python is not installed correctly. Please install it to use lldb-dap.",
+          {
+            modal: true,
+            detail: pythonCheckProcess.stderr?.toString() ?? "",
+          },
+        );
+        return undefined;
       }
+    }
+
+    this.serverInfo = new Promise((resolve, reject) => {
       const process = child_process.spawn(dapPath, dapArgs, options);
       process.on("error", (error) => {
         reject(error);

>From 8dc0101e9bc6a22f8992b2f06fa2a5ee49a8ad22 Mon Sep 17 00:00:00 2001
From: Charles Zablit <c_zablit at apple.com>
Date: Wed, 29 Apr 2026 12:22:53 +0100
Subject: [PATCH 3/3] exit with 0 if lldb-dap was not built with Python support

---
 lldb/tools/lldb-dap/tool/lldb-dap.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lldb/tools/lldb-dap/tool/lldb-dap.cpp b/lldb/tools/lldb-dap/tool/lldb-dap.cpp
index 61d42ed49ffa1..f91004dcf78ce 100644
--- a/lldb/tools/lldb-dap/tool/lldb-dap.cpp
+++ b/lldb/tools/lldb-dap/tool/lldb-dap.cpp
@@ -668,6 +668,10 @@ int main(int argc, char *argv[]) {
 
 #ifdef _WIN32
   if (input_args.hasArg(OPT_check_python)) {
+#ifndef LLDB_ENABLE_PYTHON
+    llvm::outs() << "lldb-dap was not built with Python support" << '\n';
+    return EXIT_SUCCESS;
+#endif
     auto python_path_or_err = SetupPythonRuntimeLibrary();
     if (!python_path_or_err) {
       llvm::WithColor::error()