The Build extension integrates the Free Pascal Compiler (FPC) and pas2js into VS Code. It enables compilation, cleanup, and uses-clause formatting directly from the editor.

The Build extension provides:

• FPC Integration - Native Pascal compilation for desktop and server
• pas2js Integration - Transpilation to JavaScript for web applications
• Problem Matcher - Compiler errors are displayed in the Problems panel
• Uses Formatter - Automatic formatting of uses clauses

1. Open a Pascal file (.pas, .lpr, .dpr)
2. Press Ctrl+Shift+B or run WvdS: Build Project
3. The compiler runs in the Terminal
4. Errors appear in the Problems panel

The extension automatically selects the correct compiler:

The formatter organizes and cleans up uses clauses.

• Sorting - Alphabetical, by length, or none
• Grouping - Optional: RTL, LCL, Custom Units
• Indentation - Configurable indentation width
• Line Length - Automatic wrapping when exceeded
• Unused Removal - Removal of unused units

Before:

uses
  SysUtils,Classes,Forms, Dialogs,
    StdCtrls, Windows,
  MyUnit;

After (alphabetical, 2 spaces, 80 characters):

uses
  Classes, Dialogs, Forms, MyUnit, StdCtrls, SysUtils, Windows;

Right-click in a Pascal file shows the „Uses Clauses“ submenu:

• Format Uses Clauses
• Remove Unused Units

{
  "wvds.build.fpcPath": "",
  "wvds.build.pas2jsPath": ""
}

{
  // Sort order
  // "alphabetical" | "lengthAsc" | "lengthDesc" | "none"
  "wvds.usesFormatter.sortOrder": "alphabetical",
 
  // Indentation (number of spaces)
  "wvds.usesFormatter.indentSize": 2,
 
  // Maximum line length
  "wvds.usesFormatter.maxLineLength": 80,
 
  // Group by type (RTL, LCL, Custom)
  "wvds.usesFormatter.groupByType": false,
 
  // Automatically remove unused units
  "wvds.usesFormatter.removeUnused": false
}

With grouping enabled (groupByType: true):

uses
  // RTL
  Classes, SysUtils,
  // LCL
  Forms, StdCtrls,
  // Custom
  MyUnit, AnotherUnit;

The extension parses compiler output and shows errors in the Problems panel.

FPC Format:

myunit.pas(42,10) Error: Identifier not found "TFoo"

pas2js Format:

myunit.pas(42,10) Error: identifier "TFoo" not found

• Click on an error to open the file at that location
• F8 jumps to the next error
• Shift+F8 jumps to the previous error

Create a build.cfg in the project folder for project-specific settings:

[build]
compiler=fpc
target=windows-x64
mode=debug
 
[debug]
optimizations=off
symbols=on
assertions=on
 
[release]
optimizations=3
symbols=off
assertions=off

Cause: FPC/pas2js not configured.

Solution:

1. Open WvdS: Toolchain Configuration…
2. Configure the compiler path
3. Alternatively: Set wvds.build.fpcPath in settings.json

Cause: Compiler output deviates from expected format.

Solution:

1. Check the Terminal output for errors
2. Ensure the compiler version is compatible
3. Report the issue on GitHub

Cause: No uses clause found or file not supported.

Solution:

1. Ensure the file is a .pas, .pp, .lpr, .dpr, or .inc
2. Check if a uses clause exists
3. Check the settings

• Core Extension - Toolchain Configuration
• Projects Extension - Project Templates
• Packaging Extension - Create VSIX