fix: detect and install Visual Studio Build Tools for Rust on Windows

The real issue on Windows was missing MSVC linker (link.exe) required by Rust.
Added detection of linker errors and automatic installation of Visual Studio
Build Tools via winget.

Changes:
- Detect link.exe errors and offer to install VS Build Tools
- Use winget to install Microsoft.VisualStudio.2022.BuildTools
- Update manual instructions to highlight build tools prerequisite
- Provide direct link to VS Build Tools download page

This addresses the cargo compilation failures on Windows 11.

Author: elasticdotventures

CHANGELOG.md

@@ -11,7 +11,8 @@
 ### Features
 
 - add winget support to automatically install Rust/Cargo on Windows when missing ([just-lsp-installer.ts:259](https://github.com/elasticdotventures/just-vscode-extension/blob/main/src/just-lsp-installer.ts#L259))
-- improve manual installation instructions with platform-specific guidance including winget commands
+- detect missing Visual Studio Build Tools and offer automatic installation via winget
+- improve manual installation instructions with platform-specific guidance including build tools prerequisites
 
 ### Bug Fixes
 

src/just-lsp-installer.ts

@@ -385,6 +385,58 @@ export class JustLspInstaller {
         } catch (error) {
             const errorMsg = error instanceof Error ? error.message : String(error);
             logger.errorFromException(error, 'Cargo installation failed', 'JustLspInstaller');
+
+            // Check if this is a linker error indicating missing Visual Studio Build Tools
+            if (errorMsg.includes('link.exe') && errorMsg.includes('Visual Studio build tools')) {
+                if (process.platform === 'win32') {
+                    const choice = await vscode.window.showErrorMessage(
+                        'Rust compilation requires Visual Studio Build Tools with C++ support. Would you like to install them?',
+                        'Install Build Tools',
+                        'Manual Instructions',
+                        'Cancel'
+                    );
+
+                    if (choice === 'Install Build Tools') {
+                        try {
+                            // Try using winget to install Visual Studio Build Tools
+                            await asyncExec('winget install --id Microsoft.VisualStudio.2022.BuildTools --accept-source-agreements --accept-package-agreements', {
+                                timeout: 600000 // 10 minutes
+                            });
+
+                            vscode.window.showInformationMessage(
+                                'Visual Studio Build Tools installed. Please restart VS Code and try installing just-lsp again.',
+                                'Reload Window'
+                            ).then(choice => {
+                                if (choice === 'Reload Window') {
+                                    vscode.commands.executeCommand('workbench.action.reloadWindow');
+                                }
+                            });
+
+                            return {
+                                success: false,
+                                error: 'Visual Studio Build Tools installed. Please reload VS Code and retry installation.'
+                            };
+                        } catch (installError) {
+                            vscode.window.showErrorMessage(
+                                'Failed to install Build Tools automatically. Please install manually.',
+                                'Open Instructions'
+                            ).then(choice => {
+                                if (choice === 'Open Instructions') {
+                                    vscode.env.openExternal(vscode.Uri.parse('https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2022'));
+                                }
+                            });
+                        }
+                    } else if (choice === 'Manual Instructions') {
+                        vscode.env.openExternal(vscode.Uri.parse('https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2022'));
+                    }
+                }
+
+                return {
+                    success: false,
+                    error: 'Missing Visual Studio Build Tools with C++ support. Required for compiling Rust programs on Windows.'
+                };
+            }
+
             return {
                 success: false,
                 error: `Cargo installation failed: ${errorMsg}`
@@ -419,6 +471,19 @@ export class JustLspInstaller {
             instructions += `
 ## Windows Installation
 
+### Prerequisites
+**IMPORTANT**: Rust on Windows requires Visual Studio Build Tools with C++ support.
+
+Install build tools:
+\`\`\`powershell
+# Option A: Install via winget
+winget install Microsoft.VisualStudio.2022.BuildTools
+
+# Option B: Download manually from:
+# https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2022
+# Make sure to select "Desktop development with C++" workload
+\`\`\`
+
 ### Option 1: Install with Cargo (Recommended)
 \`\`\`powershell
 # If you don't have Rust/Cargo installed: