SaC Language Support

May 11, 2026 ยท View on GitHub

SaC Language Support adds first-class editing support for SaC (Single Assignment C) in Visual Studio Code.

It provides:

  • SaC language registration for .sac files
  • Syntax highlighting and language configuration
  • Compiler-backed diagnostics via sac2c (Problems panel + editor squiggles)

Why Use This Extension?

  • Faster feedback while writing SaC code
  • Clear diagnostics integrated into the editor
  • Flexible compiler execution (local, wsl, docker)

Features

1. Syntax Highlighting

SaC keywords, operators, comments, and language constructs are highlighted out of the box.

Syntax Highlighting

2. Compiler Diagnostics in Editor

Diagnostics from sac2c are shown as VS Code Problems and inline squiggles.

Diagnostics View

3. Configurable Diagnostic Presentation

Choose how diagnostics are displayed:

  • expanded
  • smart
  • hybrid

Diagnostic Styles

4. Formatter and Local Rules

SaC formatter supports document/range formatting, optional format-on-save, and workspace-local .sac-format files with syntax highlighting and hover tooltips.

Formatting precedence is:

  1. VS Code settings under sac.format.*
  2. nearest .sac-format
  3. built-in defaults

Use the command "SaC: Generate Default .sac-format File" to scaffold a .sac-format in your workspace root.

See docs/formatting.md for supported keys and configuration.

Requirements

Syntax highlighting works without external tools.

For diagnostics, sac2c must be available through one of:

  • sac.compiler.path (explicit executable path)
  • bundled compiler in vendor/sac2c/<channel>/<platform-target>/
  • system sac2c on PATH

Supported execution backends:

  • local
  • wsl (Windows host only)
  • docker

Extension Settings

Common settings:

  • sac.languageServer.enable
  • sac.features.languageServer.enable
  • sac.features.formatter.enable
  • sac.features.outline.enable
  • sac.features.commands.enable
  • sac.features.chatParticipant.enable
  • sac.diagnostics.mode (onSave, onType, manual)
  • sac.diagnostics.presentation (expanded, smart, hybrid)
  • sac.diagnostics.includeRelatedInformation
  • sac.diagnostics.includeStackInMessage
  • sac.diagnostics.maxStackFrames
  • sac.diagnostics.workspaceScan.enabled
  • sac.compiler.channel (stable, develop, system)
  • sac.compiler.path
  • sac.compiler.executionBackend (local, wsl, docker)
  • sac.compiler.extraArgs
  • sac.format.enable
  • sac.format.onSave
  • sac.format.indentSize
  • sac.format.normalizeGuards
  • sac.format.expandInlineWithLoops
  • sac.format.expandInlineComprehensions
  • sac.format.splitInlineGuards

Workspace formatter file:

  • .sac-format with IndentSize, TabWidth, NormalizeGuards, ExpandInlineWithLoops, ExpandInlineComprehensions, SplitInlineGuards

Default structured messaging args:

-cti-no-color -cti-no-source -cti-no-hint -cti-no-explain -cti-message-length 0 -cti-primary-header-format "%s: " -cti-continuation-header-format "%.0s"

If your sac2c version uses different flags, override sac.compiler.messaging.args.

Quick Start

  1. Install the extension.
  2. Open a .sac file.
  3. Ensure diagnostics mode is enabled (for example onSave).
  4. Configure compiler path/backend if needed.

Examples

Minimal SaC file

int main() {
    return 0;
}

Trigger diagnostics

Create a small typing or semantic error in a .sac file and save to see diagnostics in the Problems panel.

Windows Notes

If you are on Windows and do not have a native sac2c binary, recommended options are:

  • Use VS Code Remote WSL and run backend local inside WSL
  • Use backend wsl
  • Use backend docker

Documentation

  • Diagnostics pipeline: docs/diagnostics-pipeline.md
  • Editor-agnostic diagnostics notes: docs/editor-agnostic-diagnostics.md
  • Copilot plugin and AI extension integration: docs/copilot-plugin.md
  • Support: SUPPORT.md
  • Contributing: CONTRIBUTING.md

Feedback

Issues and feature requests are welcome: