Server implementing the Microsoft Language Protocol for Ada and SPARK
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Ada Language Server

Build binaries GitHub tag (latest by date) VS Marketplace Open VSX Registry Gitpod ready-to-code

This repository contains an implementation of the Microsoft Language Server Protocol for Ada/SPARK.

Current features:

  • GNAT project files support.
  • Basic Alire support.
  • Code completion for names, keywords, aggregates, etc.
  • Code navigation, such as Go to Definition/Declaration, Find All References, Call Hierarchies, etc.
  • Code refactoring like insert named associations, auto-add with-clauses, etc.
  • Document/Workspace symbol search.
  • Code folding and formatting.

We also provide Visual Studio Code extension at the VS Marketplace and at the Open VSX Registry.

Table of Contents


You can build language server from sources. To build it from sources install dependencies and run


It will build .obj/server/ada_language_server file.


To build the language server you need:

Project files of the libraries must be available via the GPR_PROJECT_PATH environment variable.

If you intend to use VS Code on this workspace, it is recommended to check out these dependencies under subprojects/ or install them under subprojects/prefix. That will make them automatically visible to the VS Code Ada extension in this workspace.

To run the language server you need gnatls (part of GNAT installation) somewhere in the path.


The ada_language_server doesn't require any command line options, but it understands these options:

  • --tracefile=<FILE> - Full path to a file containing traces configuration
  • --config=<FILE> - Full path to a JSON file containing the server's configuration
  • --help - Display supported command like options and exit.

You can turn some debugging and experimental features through the traces file.

The server also gets configuration via workspace/didChangeConfiguration notification and initializationOptions of initialize request. See more details here. Each LSP client provides its-own way to set such settings. You can use the --config option if you want to provide the configuration directly via a JSON file instead of specifying it via the requests listed just above.

Supported LSP Server Requests

See WiKi page for the list of supported requests.

Protocol extensions

The Ada Language Server supports some features that are not in the official Language Server Protocol specification. See corresponding document.

How to use the VScode extension

Current limitations and differences compared to GNAT Studio

The VSCode extension has a few limitations and some differences compared to GNAT Studio:

  • Indentation/formatting: it does not support automatic indentation when adding a newline and range/document formatting might no succeed on incomplete/illegal code.

  • Toooling support: we currently provide minimal support for SPARK (see Prove/Examine tasks in the Auto-detected tasks section), but there is no support for tools such as CodePeer, GNATcheck, GNATtest or GNATcoverage.

  • Alire support: if the root folder contains an alire.toml file and there is alr executable in the PATH, then the language server fetches the project's search path, environment variables and the project's file name from the crate description.

  • Project support: there is no Scenario view: users should configure scenarios via the ada.scenarioVariables setting (see the settings list available here). You can execute the Ada: Reload project command to reload your project after saving the new scenario values (use the Ctrl+P shortcut to invoke the Command Palette, allowing you to execute commands).

    Source directories from imported projects should be added in a workspace file. If you already have a workspace file, the extension will propose you to automatically add all the source directories coming from imported projects to your workspace automatically at startup.

Bug Reporting

You can use the VS Code Issue Reporter to report issues. Just click on the Help -> Report Issue menu, select An extension for the File on entry and Language Support for Ada for the extension name. Put as many information you can in the description, like steps to reproduce, stacktraces or system information (VS Code automatically includes it by default). This will create a GitHub issue in the Ada Language Server repository.

Getting started

Tutorial: Using Ada in VS Code.


See a dedicated document with the list of available refactorings.

Auto-detected tasks

The extension includes a task provider. It provides the following "auto-detected" tasks (under /Terminal/Run Task... menu):

  • "ada: Build current project" - launch gprbuild to build the current GPR project
  • "ada: Check current file" - launch gprbuild to check errors in the current editor
  • "ada: Clean current project" - launch gprclean to clean the current GPR project
  • "ada: Examine project" - launch gnatprove in flow analysis mode on the current GPR project
  • "ada: Examine file" - launch gnatprove in flow analysis mode on the file in the current editor
  • "ada: Examine subprogram" - launch gnatprove in flow analysis mode on the current subprogram in the current editor
  • "ada: Prove project" - launch gnatprove on the current GPR project
  • "ada: Prove file" - launch gnatprove on the file in the current editor
  • "ada: Prove subprogram" - launch gnatprove on the current subprogram in the current editor
  • "ada: Prove selected region" - launch gnatprove on the selected region in the current editor
  • "ada: Prove line" - launch gnatprove on the cursor line in the current editor
  • "ada: Clean project for proof" - launch gnatprove on the current GPR project to clean proof artefacts

You can bind keyboard shortcuts to them by adding to the keybindings.json file:

  "key": "alt+v",
  "command": "workbench.action.tasks.runTask",
  "args": "ada: Check current file",
  "when": "editorLangId == ada"

Short demo

A demo for auto-detected tasks

Task customization

You can customize autodetected tasks by providing extra tool command line options via args property in the tasks.json:

	"version": "2.0.0",
	"tasks": [
			"type": "gnat",
			"taskKind": "buildProject",
			"problemMatcher": [
			"group": "build",
			"label": "ada: Build project",
			"args": ["-gargs", "-vh"]

Commands and shortcuts

The extension contributes a few commands and corresponding key bindings.

Ada: Go to other file

This command switches between specification and implementation Ada files. The default shortcut is Alt+O.

Ada: Add subprogram box

This command inserts a comment box before the current subprogram body. The default shortcut is Alt+Shift+B.

Ada: Reload project

This command reloads the current project. The default shortcut is None.

Launch the extension to debug it

For the moment, this repository includes a vscode extension that is used as the reference extension for this implementation.

You can try it by running:

code --extensionDevelopmentPath=<path_to_this_repo>/integration/vscode/ada <workspace directory>


You can configure the extension via the .vscode/settings.json settings file. See the setting list here.

Here is an example config file from the gnatcov project:

    "ada.projectFile": "gnatcov.gpr",
    "ada.scenarioVariables": {
        "BINUTILS_BUILD_DIR": "/null",
        "BINUTILS_SRC_DIR": "/null"
   "ada.defaultCharset": "utf-8",
   "ada.enableDiagnostics": false,
   "ada.renameInComments": false

Integration with other editors and IDEs

Integration with Coc.NVim

If you want to use the Ada Language Server with Vim/Neovim, you can use the Coc.NVim. You'll have to install the Ada Language Server manually somewhere on your computer. Follow installation instructions on Coc.NVim website and then configure the Ada Language Server with :CocConfig:

  "languageserver": {
    "ada": {
      "settings": {
        "ada": {
          "projectFile": "gnat/vss_text.gpr"
      "command": "<path>/ada_language_server",
      "filetypes": [

Integration with vim-lsp

If you want to integrate the Ada Language Server into vim, you can use the vim-lsp.

You'll have to install the Ada Language Server manually somewhere on your computer, and then you can add the following line to your .vimrc file:

if executable('ada_language_server')
    au User lsp_setup call lsp#register_server({
        \ 'name': 'ada_language_server',
        \ 'cmd': ['ada_language_server'],
        \ 'allowlist': ['ada'],
        \ 'workspace_config': {'ada': {
        \     'projectFile': "project.gpr",
        \     'scenarioVariables': {"ARCH": "x86_64-pc-linux-gnu"}}},
        \ })

Integration with LanguageClient-Neovim

If you want to integrate the Ada Language Server into Neovim, you can use the LanguageClient-neovim.

You'll have to install the Ada Language Server manually somewhere on your computer, and then you can add the following line to your init.vim file:

" replace the path below with the proper path to the ada_language_server executable
let g:LanguageClient_serverCommands = {
    \ 'ada': ['path/to/ada_language_server'],
    \ }
" if you already have LanguageClient_serverCommands, just add a line for ada.

To configure the Ada Language Server for a specific workspace/project, you can use the .vim/settings.json file. It is mandatory as soon as you want to use a specific .gpr project file.

This is the way to specify a project file, eg. you cannot open a project file another way. See the setting list here.

Here is an example of a settings file:

    "ada.projectFile": "project.gpr",
    "ada.scenarioVariables": {
        "GLFW_Version": "3",
        "GLFW_Lib": "-lglfw",
        "Windowing_System": "x11"

The location where the .vim folder is located will determine the relative path of the project file (so no need to prefix with ..). When vim is opened in the folder containing this .vim directory, it will use those settings for the language server even for files which might have nothing to do with that specific project, so this needs to be taken into account. Ultimately what this means is that the configuration is determined by where you open vim.

Integration with Neovim's built-in LSP client

Neovim 0.5.0 and later have a built-in LSP client which can be used with the Ada Language Server. In order to use it with minimal effort, follow these steps:

  • Install the ada language server and make sure it's in your $PATH.
  • Use your favorite Neovim plugin manager to add the default set of LSP configuration files to Neovim.
  • Enable the Ada Language Server by adding :lua require('lspconfig').als.setup{} to your init.vim.

If you would rather not have the ada language server in your path, you can give the lsp client an absolute path to the ALS executable:

require('lspconfig').als.setup{ cmd = "/path/to/als/executable" }

Configuring the language server's settings can be achieved like this:

  settings = {
    ada = {
      projectFile = "project.gpr";
      scenarioVariables = { ... };

The Ada Language Server's settings are described here. Configuring neovim to use project-specific settings is described neovim's lspconfig wiki

Integration with emacs lsp-mode

The configuration for each project can be provided using a .dir-locals.el file defined at the root of each project.

The scenario variables should be declared in your .emacs or any loaded Emacs configuration file.

(defgroup project-build nil
  "LSP options for Project"
  :group 'ada-mode)

(defcustom project-build-type "Debug"
  "Controls the type of build of a project.
   Default is Debug, other choices are Release and Coverage."
  :type '(choice
          (const "Debug")
          (const "Coverage")
          (const "Release"))
  :group 'project-build)

Your .dir-locals.el in the project root should be similar to:

((ada-mode .
  ((eval . (lsp-register-custom-settings
      '(("ada.scenarioVariables.BINUTILS_SRC_DIR" project-binutils-dir)
        ("ada.scenarioVariables.BUILD_TYPE" project-build-type "Release"))))
   (lsp-ada-project-file . "/home/username/project/project.gpr"))

The lsp-mode provides built-in support for the ada_language_server and defines default customizable configuration values in the lsp-ada group that can be edited similarly to lsp-ada-project-file in the example above.

Integration with QtCreator

Starting with version 4.9, QtCreator supports a LSP plugin. Follow the official documentation to configure the Ada Language Server in this plugin. Make sure to set Startup behavior to Start Server per Project, otherwise QtCreator won't provide the project root to the Ada Language Server. QtCreator doesn't send any configuration request to the language server, so the only option to enable project support is to have a single .gpr file in the QtCreator project folder. For a projectless configuration, you could also place all Ada sources in the project root folder, this should work as well.

Refactoring Tools

See corresponding document.

Authors & Contributors

  • Maintained by AdaCore.
  • Original author @MaximReznik.
  • Support for the Visual Studio Code classifier and snippets contributed by @Entomy.


Feel free to dive in! Read the developer's guide.

Don't hesitate to open an issue or submit PRs.



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